Search

Summary Background Surface treatment of miniscrews was implemented to determine whether its application increased bone-to-surface contact and enhanced the interlock between the device and the surrounding bone. Objectives To compare the success rate of surface-treated and non-treated orthodontic miniscrews used as reinforcement of anchorage during treatment with the Herbst appliance. Trial design Split-mouth design with an allocation ratio of 1:1. Methods Eligibility criteria to enrol patients were skeletal and dental class II patients with a retrusive chin, use of the Herbst appliance to correct malocclusion, need for skeletal anchorage using a miniscrew both in the left and right side of the mouth, absence of systemic diseases, absence of using drugs that alter bone metabolism, and good oral hygiene. Patients received self-drilling miniscrews without surface treatment and with surface treatment. Both types presented a 1.4 or 1.2 mm diameter. Miniscrews were inserted between the first molar and second premolars or between the two premolars. The force applied to the screws was an elastic chain from the head of the miniscrews to a direct button applied on the canines. The success rate of each type of miniscrew was considered the primary outcome, and the association of success with demographical, clinical, and geometrical characteristics was investigated. Differences were tested by the generalised linear mixed effects model for the split-mouth design. Differences with a P-value < 0.05 were selected as significant. Randomisation A randomisation list was created for the mouth side assignment. Blinding The study was single blinded with regard to the statistical analysis. Results Thirty-nine miniscrews of the non-treated type and 39 miniscrews of the surface-treated type were inserted in 39 patients (23 female and 16 male, mean age: 15.55 ± 7.91) recruited between March 2018 and December 2020 with a split-mouth study design. The mean therapy duration was 9.3 months (SD = 1.31). No differences in failure rate were observed between miniscrew types. No serious harm was observed. Conclusions The success rate of surface-treated and non-treated miniscrews showed no significant differences. Registration This trial was not registered.

Summary Background There has been an increased interest in conducting healthcare economic evaluations. Also, orthodontic treatments have gathered focus from an economic point of view, however orthodontic research seldom examines both clinical and economic outcomes. Objective To evaluate and compare the costs of three retention methods: a bonded retainer to the maxillary four incisors, a bonded retainer to the maxillary four incisors and canines, and a removable vacuum-formed retainer (VFR) in the maxilla. The null hypothesis was that there was no difference in costs for the three types of retention methods. Trial design Three-arm, parallel group, single-centre, randomized controlled trial. Materials and methods Ninety adolescent patients, 54 girls and 36 boys, treated with fixed or removable retainers in the maxilla, were recruited to the study. The patients were randomized in blocks of 30, by an independent person, to one of three groups: bonded multistranded PentaOne (Masel Orthodontics) retainer 13-23, bonded multistranded PentaOne (Masel Orthodontics) retainer 12-22, and removable VFR. A cost analysis was made regarding chair time costs based on the costs per hour for the specialist in orthodontics, and material costs plus any eventual costs for repairs of the appliance. Changes in Little’s irregularity index and in single contact point discrepancies (CPDs) were measured on digitalized three-dimensional study casts. Data were evaluated on an intention-to-treat basis. The analysis was performed at 2 years of retention. Results No statistically significant difference in costs between the maxillary fixed retainers and the VFRs was found, however, the material and emergency costs were significantly higher for the VFR compared with the bonded retainers. All three retention methods showed equally effective retention capacity, and no statistically significant differences in irregularity or CPDs of the maxillary anterior teeth in the three groups was detected. Limitations It was a single-centre trial, and hence less generalizable. Costs depended on local factors, and consequently, cannot be directly transferred to other settings. Conclusions All three retention methods can be recommended when considering costs and retention capacity. Trial registration NCT04616755.

Summary Background In orthodontics, the retention phase can be considered challenging and unpredictable. Therefore, evidence obtained from different retention protocols is important to facilitate clinical decision-making. Objectives This systematic review aimed to compare the clinical effectiveness of bonded versus vacuum-formed retainers (VFRs) regarding their capacity to maintain treatment stability, periodontal effects, and failure rates. Search methods and eligibility criteria Ten databases comprising published and unpublished literature were systematically searched up to August 2021. Randomized clinical trials (RCTs) comparing both retainers were included. Data collection and analysis The risk of bias (RoB) evaluation was performed with the Cochrane Collaboration RoB Tool 2.0. All steps of the screening phase and RoB assessment were performed independently by two reviewers. The Grade of Recommendations, Assessment, Development, and Evaluation (GRADE) was used to evaluate the certainty of the evidence. Results Initial database search yielded 923 studies. After duplicates removal and full-text assessment, five RCTs remained. Overall, the studies presented Low RoB, except one study judged with ‘Some concerns’. Based on the included studies, on a short-term (3–6 months) and long-term (4 years) basis, bonded retainers (BRs) were more effective to maintain treatment stability than VFRs in the lower arch. However, from 12 to 24 months both retainers presented the same efficacy. In the upper arch, the retainers were equally effective. BRs were associated with greater plaque and calculus accumulation than VFRs after 12 months. The retainers’ failure rates were similar in the upper arch on the first year of retention; however, after 2 years VFRs showed significantly greater failure rates. Contrarily, BRs presented greater failure rates in the lower arch than VFRs. Limitations The findings of the included studies may be influenced by different factors related to the unpredictability of relapse. Conclusions Most of the evidence generated in this systematic review derived from a moderate level of certainty. In the lower arch, BRs are more effective than VFRs to maintain treatment stability in the initial 6 months of retention and in the long term. In the upper arch, both retention protocols are equally effective. Registration Regist0ration number: PROSPERO CRD42020199392. Funding Coordination for the Improvement of Higher Educational Personnel (CAPES, Process code-001).

Summary Objectives This study aimed to compare the immediate influence of four commonly used retainer wires on tooth mobility following orthodontic treatment with fixed appliances. Materials and Methods Eighty patients after orthodontic treatment were assigned to four study groups (n = 20 in each group). Groups were provided with directly bonded fixed retainers—0.0150″ (group A), 0.0175″ (group B), 0.016 × 0.022″ (group C), and 0.0215″ (group D). Tooth mobility was measured using the Periotest device at two times—after removal of fixed appliance (T1) and after bonding of the retainer (T2). Values of tooth mobility, ‘Periotest values’, were analysed between groups and compared with the physiologic tooth mobility in a control group of untreated patients (n = 65). Kruskal–Wallis H, Mann–Whitney U, Dunn’s test, Fisher’s exact test, and binary logistic regression tests were used to analyze the data. Results Tooth mobility after orthodontic treatment was significantly increased. While canines remained within normal range of tooth mobility, values for incisors increased on average to the first degree of tooth mobility (slight mobility). Logistic regression analysis identified age as a significant predictor for increased tooth mobility (P = 0.032) with odds ratio 1.065 (95% CI 1.005–1.128), with mobility increasing with age. After bonding of the retainer in all four groups, the tooth mobility was reduced to values which were not significantly different form normal physiological values found in the control group (P > 0.05). There were no differences in the amount of change or in tooth mobility values at T2 between the different types of bonded retainers. Limitations Age of subjects in the control group was significantly higher than that in the study groups. An alternation method was used instead of randomization to distribute the four different types of retainers. Conclusions All of the retainer wires were able to successfully reduce the increased tooth mobility caused by orthodontic treatment to normal levels. The values of tooth mobility after placement of retainers were within the range of physiologic tooth mobility.

Summary Introduction This study investigated the effect of the timing of second molar bonding on the time required for the levelling of the mandibular dental arch. Trial design Single-centre two-arm parallel randomized clinical trial using random permuted blocks. Allocation concealment was achieved through sealed envelopes. There was blinding in outcome assessment, but not of patient or operator. Methods Thirty-six patients (12–18 years old) with mild to moderate crowding and fully erupted mandibular second molars were assigned randomly (1:1 ratio) in two groups. Group A started fixed orthodontic treatment by bracket bonding in both jaws. Initial wire was 0.014” NiTi. Lower second molar tubes were bonded at the time of 0.016” x 0.022” NiTi wire placement. Group B was same as Group A, but second lower molars were bonded at the first appointment. Placement of the 0.017” x 0.025” stainless steel wire in the mandibular arch was considered the primary endpoint of the trial, indicating the completion of the levelling phase. The days required from bonding to the endpoint comprised the main outcome. Non-parametric statistics were applied. Results There were two dropouts in each group. The compared groups had similar baseline characteristics regarding age, sex, overjet, overbite, space in the dental arch, average Curve of Spee (CoS), and maximum CoS. Group A tended to require more days for levelling (median: 203 days) than Group B (median: 168 days). However, this difference was not statistically significant (P = 0.128). From the tested occlusal factors, only initial overjet was found to be moderately associated with the days required to complete levelling of the mandibular arch (r = 0.45, P = 0.009). Conclusions In the frame of the current study, the duration of the levelling phase of orthodontic treatment with fixed appliances was not affected by the timing of second molar inclusion in the appliance. Future research could aim in cases with deep CoS to generalize the present findings and in larger sample sizes.

Summary Background Growth and development might lead to anchorage loss during orthodontic treatment, such as the mesial drift of molars, the compensation characteristics of upper molars following mandibular growth, or the angulation of molars before treatment. Different anchorage reinforcement devices have been developed to prevent mechanical anchorage loss, but the anchorage loss resulting from physiological factors should also be taken into account. Objective To explore the efficacy of a new strategy to control physiologic anchorage compared with that of the conventional straight-wire appliance. Trial design Randomized controlled trial (RCT). Methods Participants of Han ethnicity were randomized into the physiologic anchorage spee-wire system (PASS) group or McLaughlin–Bennett–Trevisi (MBT™) straight-wire group by minimization random allocation. The eligibility criteria were patients with a Class I or II molar relationship, permanent dentition (11–35 years old), fixed appliances involving the extraction of at least two upper first premolars, and medium or maximum anchorage requirements. Pre-treatment and post-treatment dental casts were scanned into digital casts and measured using a blinded method. Mesial displacements of the upper first molars were considered as the primary outcome for evaluating anchorage control. Measurements were taken for subgroups based on age. Results Data from 60 participants were analysed. The baseline characteristics were not significantly different between groups. Mesial displacement of the upper first molar (in mm) was 2.96 ± 1.52 in the PASS group and 2.70 ± 1.66 in the MBT group (P = 0.521). The variation in incisor torque was −6.94 ± 6.35 degree in the PASS group and −11.76 ± 7.65 degree in the MBT group (P = 0. 010). The incisor retraction (in mm) was 4.24 ± 1.99 and 5.67 ± 2.27 in the PASS and MBT groups, respectively (P = 0.012). Adverse effects were not documented in any patient. Limitation The study was a single-centre study. Conclusions Compared with the MBT group, the PASS group without additional anchorage devices could attain well anchorage control by considering the dentoalveolar compensation of anchor teeth. Registration This RCT was registered at the Chinese Clinical Trial Registry (Chictr.org.cn) ChiCTR-TRC-13003260.

SummaryObjectivesThe purpose of this study was to compare the results of skeletal anchorage (SAMP) and tooth- borne (TBMP) maxillary protraction followed by fixed appliance in growing skeletal Class III patients.Materials and methodsPatients treated with maxillary protraction were selected and classified into two groups (SAMP: n = 19, mean age = 11.19 years; TBMP: n = 27, mean age = 11.21 years). Lateral cephalograms taken before treatment (T0), after the maxillary protraction (T1), and after the fixed appliance treatment (T2) were analysed and all variables were statistically tested to find difference between the two groups.ResultsCompared to the TBMP, the SAMP showed significant forward growth of maxilla (Co-A point and SN-Orbitale) and improvement in intermaxillary relationship (ANB, AB to mandible plane, and APDI) after the overall treatment (T0–T2), with no significant sagittal changes in maxilla or mandible throughout the fixed appliance treatment (T1–T2).LimitationsIn maxillary protraction, effects of skeletal anchorage were retrospectively compared with those of dental anchorage, not with Class I or III control.Conclusions and implicationsAfter maxillary protraction, skeletal and tooth-borne anchorage did not cause significant differences in the residual growth of maxilla throughout the phase II treatment. Orthopaedic effects with skeletal anchorage showed appropriate stability in maxilla and intermaxillary relationship even after fixed appliance treatment.

Summary Background Evidence concerning the most appropriate retention strategy after orthodontic treatment is still inconclusive. Objective This trial compares the retentive capacity of vacuum-formed Essix C-retainers (VFR) and bonded cuspid-to-cuspid retainers (CTC) in the mandible 6 and 18 months after orthodontic treatment. Trial design A single-centre two-arm parallel-group randomized controlled trial. Methods This study included 104 adolescent patients, computer-generated randomized with sequentially numbered, opaque, and sealed envelopes into two groups and stratified by gender (52 females and 52 males). The patients were treated with fixed appliances with and without tooth extractions in both jaws and were ready for debond. In the intervention arm, patients received a VFR (n = 52); in the active comparator arm, patients received a CTC (n = 52). Dental casts were obtained at debond (T1), after 6 months (T2), and after 18 months (T3). The casts were digitized. The retentive capacity was evaluated on digital three-dimensional models using Little’s Irregularity Index (LII), overbite, overjet, arch length, and intermolar and intercanine width. Results Baseline values were similar for both groups. Statistically significant increases were noted in LII and overbite, mainly between T1 and T2, but also between T1 and T3 in the VFR group (LII = 0.52 mm, P < 0.001, overbite = 0.51 mm, P < 0.001) and in the CTC group (LII = 0.45 mm P < 0.001, overbite = 0.36 mm, P < 0.001). There were no significant differences between groups. Overjet showed small variations during the observation periods but was overall stable within and between groups after 18 months. Arch length decreased slightly in both groups after 6 and 18 months. Intermolar and intercanine widths remained stable after debond. Limitations Patients, operator, and outcome assessor could not be blinded due to the study design. Conclusions VFR and CTC have the same retention capacity in the mandible after 6 and 18 months. Relapse mainly occurs during the first 6 months of retention, but the post-treatment changes are generally small. Shorter VFRs in the mandible do not cause negative vertical effects. Part-time wear regimen is not associated with increased relapse. Trial registration NCT03070444.

Summary Objectives The aim of this study was to compare vacuum-formed thermoplastic retainers (VFRs) constructed on stone models (VFR-CV) and those constructed on three-dimensional (3D) printed models (VFR-3D) based on patients’ perspective and post-treatment stability. Study design The research was designed as a crossover, randomized control trial. Materials and methods Subjects comprised patients receiving fixed appliances at a teaching institution and indicated for VFRs. Post-treatment stone models were scanned with a structured-light scanner. A fused deposition modelling machine was used to construct acrylonitrile-butadiene-styrene (ABS)-based replicas from the 3D scanned images. VFRs were fabricated on the original stone and printed models. Analysis comprised independent t-tests and repeated measures analysis of variance. Randomization Subjects were allocated to two groups using Latin squares methods and simple randomization. A week after debond, subjects received either VFR-CV first (group A) or VFR-3D first (group B) for 3 months, then the interventions were crossed over for another 3 months. Blinding In this single-blinded study, subjects were assigned a blinding code for data entry; data were analysed by a third party. Outcome measures The primary outcome measured was oral health-related quality of life (OHRQoL) based on Oral Health Impact Profile-14 (OHIP-14). Secondary outcome was post-treatment stability measured using Little’s Irregularity Index (LII). Results A total of 30 subjects (15 in each group) were recruited but 3 dropped out. Analysis included 13 subjects from group A and 14 subjects from group B. Group A showed an increase in LII (P < 0.05) after wearing VFR-CV and VFR-3D, whereas group B had no significant increase in LII after wearing both VFRs. Both groups reported significant improvement in OHRQoL after the first intervention but no significant differences after the second intervention. LII changes and OHIP-14 scores at T2 and T3 between groups, and overall between the retainers were not significantly different. No harm was reported during the study. Conclusion VFRs made on ABS-based 3D printed models showed no differences in terms of patients’ OHRQoL and stability compared with conventionally made retainers. Registration NCT02866617 (ClinicalTrials.gov).

Objective To compare treatment duration between 0.018-inch and 0.022-inch slot systems and determine factors influencing treatment duration. Subjects and methods Eligible participants aged 12 years or over were allocated to the 0.018-inch or 0.022-inch slot MBT appliance (3M-Unitek, Monrovia, California, USA) using block randomization in groups of 10. Outcome measures included duration of: 1. overall treatment, 2. levelling and alignment, 3. working and finishing, and 4. appointment numbers and other treatment-related factors. Parametric tests (independent samples t-test) and non-parametric tests (chi-square with Fisher's exact tests and Mann-Whitney U-test) assessed differences between groups. A multiple linear regression analysis identified factors influencing treatment duration (P Results Of the 187 participants randomized (1:1 ratio), 34 withdrew or were excluded (protocol deviations or poor cooperation). There were 77 patients in the 0.018-inch slot group and 76 patients in the 0.022-inch slot group (overall mean age: 19.1 years). Baseline characteristics were similar between groups (P > 0.05). The mean duration of treatment for the 0.018-inch and 0.022-inch slot groups was 29.3 and 31.2 months, respectively. There were no statistically significant differences between the two treatment groups in terms of treatment duration, duration of the key stages of treatment, and number of appointments (P > 0.05). The regression analysis revealed 33.0 per cent of variance in treatment duration was explained by age at bonding, Class II division 2 malocclusion, number of failed appointments, number of emergency appointments, and transfer to another clinician. There were no adverse events. Limitations It was impossible to blind clinicians or patients to allocation and oral hygiene and periodontal outcomes were not assessed. Conclusions There was no statistically or clinically significant difference in treatment duration between 0.018-inch and 0.022-inch slot bracket systems. Increasing patient age, Class II division 2 malocclusion, number of failed and emergency appointments, and multi-operator treatment all increase orthodontic treatment duration. Registration The trial was registered with ClinicalTrials.gov on 5 March 2014, registration number: NCT02080338. Protocol The protocol was published at DOI: 10.1186/1745-6215-15-389.

Objective To compare orthodontically induced inflammatory root resorption (OIIRR) and patient perception of pain during orthodontic treatment between 0.018-inch and 0.022-inch slot bracket systems. Subjects and methods Eligible participants aged 12 years or above were allocated to treatment with the 0.018-inch or 0.022-inch slot MBT appliance (3M Unitek, Monrovia, California, USA) using block randomization in groups of 10. OIIRR was assessed radiographically using standardized periapical radiographs before and after 9 months from the start of treatment. Patient perception of pain was assessed using a validated patient questionnaire at 6 months from the start of treatment. Parametric tests (t-test) and non-parametric tests (chi-square with Fisher's exact tests and Kruskal-Wallis test) assessed differences between the groups (P Results Of the 187 participants randomized (1:1 ratio), 34 withdrew or were excluded (protocol deviations or poor cooperation). There were 77 patients in the 0.018-inch slot group and 76 patients in the 0.022-inch slot group (overall mean age: 19.1 years). Baseline characteristics were similar between groups (P > 0.05). There was no significant difference in the severity of the OIIRR nor patient perception of pain between the two study groups (P = 0.115 and P = 0.08 respectively). The correlation between the severity of OIIRR and abnormal root morphology or history of dental trauma was not statistically significant (P = 0.086 and P = 0.313). Moreover, there was no significant correlation between the severity of OIIRR and pain during treatment (R = 0.045, P = 0.617). Limitations It was impossible to blind clinicians or patients to allocation, and oral hygiene and periodontal outcomes were not assessed. Conclusions The effect of bracket slot size on the severity of OIIRR and patient perception of pain are not significant. Trial registration The trial was registered with ClinicalTrials.gov on 5 March 2014, registration number: NCT02080338.

Objectives To evaluate and compare the effects of tooth-borne (TB) and tooth-bone-borne (TBB) rapid maxillary expansion (RME) on nasal airflow and resistance. Material and methods Fifty-four consecutive patients who met the eligibility criteria were recruited from September 2010 to December 2015. Of these 54 subjects, 40 agreed to participate in the part of the study involving evaluation of nasal flow and resistance. The 40 subjects were allocated to either the TB group, mean age 9.7 years (SD 1.5), or the TBB group, mean age 10.2 years (SD 1.4). All subjects performed rhinomanometric registration at baseline (T0), but only 30 attended the post-expansion registration (T1), of whom 16 had been randomized to the TB group and 14 to the TBB group. The study outcomes, nasal airflow and nasal airway resistance, were evaluated with linear regression adjusted for baseline variable of the outcome to compare the study groups with complete cases strategy as well as after multiple imputation (MI). Randomization Participants were randomly allocated in blocks of different sizes, using the concealed allocation principle in a 1:1 ratio. The randomization list was computer generated to ensure homogeneity between groups. Blinding Blinding was done only for outcome assessor due to clinical limitations. The care providers at the ENT unit who conducted all the rhinomanometry examinations were blinded to which group the patients were allocated to. Results Complete case analysis showed significantly higher post-expansion nasal airflow values for the TBB group compared with the TB group, mean difference 51.0 cm3/s (P = 0.018). The evaluation after MI showed a similar significant mean difference, 52.7 cm3/s (P = 0.020) in favour of the TBB group when taking into account the missing values from the T1 examination. Even reduction in nasal airway resistance showed similar pattern in favour of the TBB group. Limitations Our results represent the short-term effects. A longer follow-up period would have been preferable. Conclusions The TBB RME induced significantly higher nasal airway flow and lower nasal resistance values than TB RME. It might be wiser to use TBB RME in cases with constricted maxilla and upper airway obstruction. Registration This trial was not registered in any external sites. Protocol The protocol was not published before trial commencement.

Background Retainer have the potential to compromise periodontal health. Objectives Evaluate the periodontal health implications of upper and lower bonded retainers (BRs) versus upper and lower vacuum-formed retainers (VFRs) over 12 months. Trial design Two-arm parallel group multicentre randomized controlled clinical trial. Methods Sixty consecutive patients completing upper and lower fixed appliance therapy and requiring retainers were recruited from three hospital orthodontic departments. They were randomly allocated to either upper and lower labial segment BRs (n = 30) or upper and lower full-arch VFRs (n = 30). Periodontal health was assessed using the plaque and gingival indices of Silness and Loe, and the calculus index of Greene and Vermillion. Data were collected at debond and placement of the retainers (T0), 3 months (T1), 6 months (T2), and 12 months (T3). A random sequence of treatment allocation was computer-generated and implemented by sealing in sequentially numbered opaque sealed envelopes independently prepared in advance. Patients, operators, and outcome could not be blinded due to the nature of the intervention. Results Thirty patients received BRs (median age 16 years, interquartile range [IQR] = 2, 50% female, 50% male) and 30 received VFRs (median age 17 years, IQR = 4, 60% female, 40% male). Gingival inflammation decreased from baseline for both types of retainer. There was significantly less plaque and calculus accumulation and better gingival health with VFRs than BRs over the evaluated 12 months. No serious harm was observed. Limitations It is not known how much the patients chose to wear their removable retainers. The results reported are after 1 year only. Conclusions After 1 year, BRs were associated with greater accumulation of plaque and calculus than VFRs and minimally worse gingival inflammation than VFRs, but this did not appear to produce any clinically significant, adverse periodontal health problems. Trial registration This trial was not registered. Funding There was no funding.

Background There is a shortage of evidence on the best type of retainer. Objectives Evaluate upper and lower bonded retainers (BRs) versus upper and lower vacuum-formed retainers (VFRs) over 12 months, in terms of stability, retainer survival, and patient satisfaction. Trial design Two-arm parallel group multi-centre randomized controlled clinical trial. Methods Sixty consecutive patients completing fixed appliance therapy and requiring retainers were recruited from 3 hospital departments. They were randomly allocated to either upper and lower labial segment BRs (n = 30) or upper and lower full-arch VFRs (n = 30). Primary outcome was stability. Secondary outcomes were retainer survival and patient satisfaction. A random sequence of treatment allocation was computer-generated and implemented by sealing in sequentially numbered opaque sealed envelopes independently prepared in advance. Patients, operators and outcome could not be blinded due to the nature of the intervention. Results Thirty patients received BRs (median [Mdn] age 16 years, inter-quartile range [IQR] = 2) and 30 received VFRs (Mdn age 17 years, IQR = 4). Baseline characteristics were similar between groups. At 12 months, there were no statistically significant inter-group differences in post-treatment change of maxillary labial segment alignment (BR = 1.1 mm, IQR = 1.56, VFR = 0.76 mm, IQR = 1.55, P = 0.61); however, there was greater post-treatment change in the mandibular VFR group (BR = 0.77 mm, IQR = 1.46, VFR = 1.69mm, IQR = 2.00, P = 0.008). The difference in maxillary retainer survival rates were statistically non-significant, P = 0.34 (BR = 63.6%, 239.3 days, 95% confidence interval [CI] = 191.1-287.5, VFR = 73.3%, 311.1 days, 95% CI = 278.3-344.29). The mandibular BR had a lower survival rate (P = 0.01) at 12 months (BR = 50%, 239.3 days 95% CI = 191.1-287.5, VFR = 80%, 324.9 days 95% CI = 295.4-354.4). More subjects with VFRs reported discomfort (P = 0.002) and speech difficulties (P = 0.004) but found them easier to clean than those with BRs (P = 0.001). Limitations Results are after 1 year and we do not know how much the removable retainers were worn. Conclusions After 1 year, there is no evidence of a significant difference in stability or retainer survival in the maxilla. In the mandible, BRs are more effective at maintaining mandibular labial segment alignment, but have a higher failure rate. In comparison with patients wearing VFRs, patients wearing BRs reported that they caused less interference with speech, required less compliance to wear them, and were more comfortable to wear than VFRs. Patients found the BRs harder to keep clean. Trial registration The trail was not registered.

Introduction An Orthodontic SIMulator (OSIM) was used to investigate the propagation of forces and moments around a simulated archform for a gingival displaced canine and lingual displaced lateral incisor using fixed lingual orthodontic appliances. Methods In-Ovation L self-ligating lingual brackets were bonded to anatomically shaped teeth on the OSIM, and the teeth were positioned such that a G4 NiTi 0.016" large maxillary mushroom archwire could be ligated in passive position. Each trial consisted of two movements: a 3mm lingual displacement of the 1-2 lateral incisor at 0.2 mm increments, and a 1.5 mm gingival displacement of the 2-3 canine at 0.15 mm increments (n = 50). Anterior brackets were repositioned to accommodate G4 NiTi 0.016" universal straight archwires (n = 50). Tests were completed at 37°C, and force and moment data in all directions was collected for each tooth around the arch at all increments. Results In general, the straight archwire produced significantly larger forces and moments at the centre of resistance for teeth of interest than did mushroom archwires. Specifically, the straight archwire produced 2.62 N and 3.81 N more force in the direction of tooth movement on the tooth being moved for a gingival displaced canine and lingual displaced lateral incisor, respectively, as compared to mushroom archwires. Conclusions Results from this study suggest that mushroom archwires may provide better mechanics for movement of teeth in the anterior segment when using a round archwire; however, only biomechanical data was considered in this study and there are many factors that need to be considered in treatment planning.

Background Hawley retainers (HRs) and vacuum formed retainers (VFRs) are the most commonly used removable retainers in the orthodontic practice. Patients' cooperation in wearing these appliances is affected by the levels of discomfort and oral impairment. The evidence regarding their acceptably among orthodontic patients is limited. Aims To compare the acceptability of HRs and VFRs over a 6-month period in a group of fixed orthodontic patients. Trial Design Two-arm parallel-group randomized controlled trial. Methods Patients being treated at the Orthodontic Department of Saudi Swiss Consultant Dental Centre, Al-Khobar, Saudi Arabia, who met the inclusion criteria were invited to participate. Inclusion criteria were treatment only with fixed appliances, no lateral expansion treatment, no hypodontia, no cleft lip and palate, no surgical corrections, no extraction-based plans, 18 years old or greater, and willingness to wear maxillary and mandibular removable retainers. Participants were distributed randomly using concealed envelopes into two groups: HR group and VFR group. A pilot-tested questionnaire was filled at three times: 1 week after fitting of the retainer (T1), 3 months and 6 months following appliance fitting (T2 and T3, respectively). Ten questions were given on biting, fitting of the appliance, speech, appearance, oral hygiene, durability, gingival irritation, swallowing, self-confidence, and comfort. Responses were given on a visual analogue scale. Blinding was employed during data analysis. Results Ninety-four patients were included primarily. Six patients in the Hawley group and two patients in the VFR group failed to complete the study. Therefore, 86 patients were included the analysis (HR group: 41; VFR group: 45). No significant differences were found between the two groups in biting, fitting of the appliance, and hygiene perception, whereas significant differences were detected in speech (P < 0.05), appearance (P < 0.001), gingival irritation (P < 0.001), durability (P < 0.001), swallowing (P < 0.001), self-confidence, and comfort (P < 0.001). No harm to any patient was noticed during the trial. Conclusions Over a 6-month period of retention, VFR was significantly more acceptable than HR in speech, appearance, gingival irritation, swallowing, self-confidence, and comfort. Subjects in the HR group believed that their retainers were significantly more durable than those in the VFR group at the final assessment. Both retainers were equal regarding fitting of the appliance, biting, and hygiene perception. Registration Not registered. Protocol The protocol was not published before trial commencement. Funding This trial was funded by the Saudi Swiss Consultant Dental Centre.

Objectives The aim of this clinical trial was to investigate the duration of mandibular-crowding alleviation with piezotome-corticision orthodontics compared with conventional orthodontics. Design Single-centre, two-arm parallel group randomized controlled trial. Setting Orthodontic clinic at the University of Connecticut. Ethical approval The study was approved by the Institutional Review Board (IRB # 12-0147-2). Subjects and methods Forty-one adult subjects from a single centre with more than 5mm of mandibular anterior crowding were randomly allocated using block randomization into experimental and control groups. The experimental group received a corticision procedure with a piezotome on the labial aspect of the mandibular incisors in conjunction to a self-ligation fixed orthodontic appliance. The control group received the self-ligation fixed orthodontic appliance and no corticision. Same archwire sequence (0.014 inch followed by 0.014 × 0.025 inch copper-nickel-titanium) was followed for both groups. Mandibular study casts taken every 4-5 weeks were used to assess changes in the irregularity index by blinded outcome assessors. Outcome measures The time to alignment was calculated in days. Results Twenty-nine subjects (16 experimental and 13 control) completed the study. Overall, no significant difference in the time required to correct mandibular crowding with piezotome-corticision assisted (102.1 ± 34.7 days; 95% CI, 83.6 to 120.6) and conventional orthodontics (112 ± 46.2 days; 95% CI, 84-139.9) was observed. No complications with treatment or unintended consequences were observed on any of the subjects. Limitations A high attrition rate. Conclusions This randomized clinical trial found no evidence that piezotome-corticision assisted orthodontics was more efficient in alleviating mandibular anterior crowding. Registration ClinicalTrials.gov, Identifier: NCT02026258. Funding Division of Orthodontics, University of Connecticut. Conflict of Interest None.

Objective The aim was to assess the influence of long-term in vivo exposure, debris accumulation and archwire material on static and kinetic friction force among different types of brackets and archwires couples. Material and Methods Friction testing was performed among four lower incisors' brackets, conventional and self-ligating (SL), coupled with either nickel-titanium or stainless steel archwires, as-received and in vivo exposed in 18 subjects. The friction testing was performed for a sliding distance of 14 mm at a speed of 10 mm/min, with a starting force of 0.2 N. Wear and quantitative assessment of debris accumulation was performed on pictures of brackets obtained using a scanning electron microscope. Non parametric tests were used for statistical analysis. Results Only bracket type, but not exposure duration, amount of debris accumulation, archwire material or their manufacturer, was significantly correlated with both static (rho = 0.602, P < 0.001) and kinetic (rho = 0.584, P < 0.001) friction force. Within each bracket type no significant difference was observed between as-received and in vivo exposed brackets for any friction parameter except for the SL brackets in which significantly higher static and kinetic (P = 0.001, at least) friction forces were seen in in vivo exposed SL brackets (164.9 cN and 217.63 cN, respectively) in comparison with as-received SL brackets (19.69 cN and 55.72 cN, respectively). Limitation The frictional testing was performed in the dry condition which might have influenced the results. Conclusion A significant correlation was seen between friction force and bracket type, while treatment duration, amount of debris accumulation, archwire material or their manufacturer was not significantly correlated to it. Nevertheless, higher friction forces were measured among in vivo aged SL brackets in comparison with as-received ones.

Purpose The aim of this study was to characterize the surface, elemental, and mechanical alterations of orthodontic palatal implants after intraoral aging. Materials and method Nineteen consecutively retrieved implants (RET) after orthodontic treatment and three unused implants used as control (CON) were included in this study. Both groups were characterized non-destructively by Stereomicroscopy, Optical Profilometry (Sa, Sq, Sz, Sc), and SEM/EDX analysis and then destructively after metallogaphic preparation employing instrumented indentation testing (HM, EIT, ηIT, and HV) and SEM/EDX at bone-implant interface. Results All retrieved implants showed a loss of gloss with the formation of bone-like formation on the majority of them. However, no differences in surface roughness parameters were identified between macroscopically intact and retrieved regions of implants. The elements precipitated on the surface were O, C, Ca, and P while traces of Na, K, Al, S, Cl, and Mg were also identified. The surface of control sample is characterized by small pits while only Ti and Al traces were identified by EDX analysis. The presence of all the aforementioned elements apart from Ti and Al on the retrieved implants' surface should be appended to the contact of implant with bone and biological fluids while Interfacial analysis revealed a well-formed bone-implant interface. However, no significant differences were found for all mechanical properties tested between RET and CON groups. Conclusions The results of this study indicate that retrieved palatal implant surface has undergone morphological and elemental alterations probably associated with the osseointegration process during service. Insertion and functional loading did not affect the mechanical properties of implants tested.

Summary Background: Using lingual enamel surfaces for bracket placement not only has esthetic advantages, but may also be suitable in terms of reducing frequencies of enamel decalcifications. Objective: To test the null-hypothesis that there is no significant difference in enamel decalcification or cavitation incidence adjacent to and beneath bracket bases between two lingual multi-bracket (MB) appliances that are different in terms of design, material composition, and manufacturing technology (group A: WIN, DW-LingualSystems; group B: Incognito, 3M-Unitek), taking into account patient- and treatment-related variables on white spot lesion (WSL) formation. Methods: Standardized, digital, top-view photographs of 630 consecutive subjects (16214 teeth; n Incognito = 237/6076 teeth; n WIN = 393/10138 teeth; mean age: 17.47±7.8; m/f 43.2/56.8%) with completed lingual MB treatment of the upper and lower permanent teeth 1–7 were screened for decalcification or cavitation adjacent to and beneath the bracket bases before and after treatment, scored from 0 to 7. Non-parametric ANOVA was used for main effects ‘appliance type’, ‘gender’, ‘treatment complexity’, ‘grouped age’ (≤16/>16 years), and ‘treatment duration’ as covariable, at an α-level of 5%. Results: About 2.57% [5.94%] of all teeth in group A [B] developed decalcifications. Subject-related incidence was 9.59% [16.17%] for upper incisors in group A [B], and 12.98% [25.74%] for all teeth 16–46. There were significant effects by gender, age, and treatment duration. Conclusion: The null-hypothesis was rejected: sub-bracket lesions were significantly less frequent in group A, while frequencies of WSL adjacent to brackets were not significantly affected by appliance type. In view of the overall low incidences of lingual post-orthodontic white-spot lesions, the use of lingual appliances is advocated as a valid strategy for a reduction of enamel decalcifications during orthodontic treatment.

Summary Aim: The aim of this study was to evaluate microleakage under orthodontic ceramic brackets bonded with direct and different indirect bonding techniques and adhesives using micro-computed tomography. Materials and methods: A total of 30 human maxillary premolars were randomly separated into five groups with six teeth in each group. In group I, teeth were bonded directly with Transbond XT (3M Unitek). In group II, group III, group IV, and group V, teeth were bonded through an indirect technique with Custom I.Q. (Reliance Orthodontic Products), Sondhi Rapid-Set (3M Unitek), RMbond (RMO), and Transbond IDB (3M Unitek), respectively, following the manufacturer's instructions. Micro-CT system model 1172 of Skyscan (Kontich, Belgium) was used to scan all samples. NRecon (Skyscan) version 1.6, CT-Analyser V.1.11 (Skyscan), and TView (SkyScan, Bvba) software programs were used for microleakage evaluation. Microleakage values between the test groups were assessed using the Kruskal-Wallis test, while the Wilcoxon signed rank test was used for within-group comparisons. The level of significance was set at P < 0.05. Results: According to the Kruskal-Wallis analysis of variance test, there were no significant differences among the tested groups, with regard to volume and percentage (microleakage/region of interest × 100) of microleakage values (P < 0.05). The Wilcoxon signed rank test showed that coronal microleakage volume and percentage values significantly differed for RMbond and Transbond IDB groups. Limitations: In the study, only ceramic brackets were used and microleakage into mini gaps did not show up on the micro-CT image because 50% silver nitrate solution could not penetrate into mini gaps which are smaller than silver nitrate particles. Conclusion: Use of direct and indirect bonding techniques with different adhesives did not significantly affect the amount of microleakage. © The Author 2015. Published by Oxford University Press on behalf of the European Orthodontic Society.

Objectives: The goal of this study was to determine the chemical composition of the passivation layer of three clinically available orthodontic miniscrews at different depths. Materials and Methods: The miniscrews used were Aarhus Mini-Implant (AAR), IMTEC Ortho (IMT), and VectorTAS (VEC). The chemical compositions of the as-received miniscrews were determined by X-ray photoelectron spectroscopy (XPS). Data was acquired before etching the miniscrews with argon, as well as after etching at depths of 10 nm, 20 nm, 30 nm, and 80 nm. Results: The elements found in all miniscrews were mainly C, O, and Ti. Also found were other metals in small amounts, and other trace elements. All three miniscrews showed very different characteristics in surface composition. IMT had the greatest increase in Ti, as well as the most titanium metal at 80 nm. VEC remained stable at all tested depths and contained no titanium metal at 80 nm. AAR was an intermediate between the two. Conclusions: The passivation layer of the orthodontic miniscrews has different compositions depending on the brand, as well as the depth analyzed. VEC appeared to have the largest passivation layer, and IMT appeared to have the thinnest passivation layer.

Aim: To investigate the mechanical and chemical alterations of Invisalign appliances after intraoral aging. Materials and methods: Samples of Invisalign appliances (Align Technology, San Jose, California, USA) were collected following routine treatment for a mean period of 44±15 days (group INV), whereas unused aligners of the same brand were used as reference (group REF). A small sample from the central incisors region was cut from each appliance and the buccal surface was analysed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy ( n = 5). Then the appliances were cut ( n = 25) and embedded in acrylic resin, ground/polished in a grinding polishing machine, and the prepared surfaces were subjected to Instrumented Indentation Testing under 4.9 N load. Force-indentation depth curves were recorded for each group and the following parameters were calculated according to ISO 14577-1; 2002 specification: indentation modulus ( E IT), elastic to total work ratio also known as elastic index (ηIT), Martens Hardness (HM), and indentation creep ( C IT) The mean values of the mechanical properties were statistically analysed by unpaired t -test ( a = 0.05). Results: ATR-FTIR analysis confirmed the urethane based structure of the appliances, without important chemical differences attributed to the aging process. INV group showed significantly lower E IT (REF: 2466±20, INV: 2216±168MPa), HM (REF: 119±1, INV: 110±6 N mm−2) and higher ηIT (REF: 40.0±0.3, INV: 41.5±1.2%), and C IT (REF: 3.7±0.2 INV: 4.0±0.1%). The increase in ηIT indicates that INV is a more brittle than REF, whereas the increase in C IT, a decrease in creep resistance. Conclusion: Despite the lack of detectable chemical changes, intraoral aging adversely affected the mechanical properties of the Invisalign appliance.

Aim: The purpose of this study was to assess the difference of removal torque values (RTV) and the bone-to-implant contact (BIC) between the sand-blasted, large grit, and acid-etched (SLA) surface-treated and the machined surface (MA) miniscrews. Material and methods: Miniscrews used in this study were 6mm long with a diameter of 1.5mm. A total of 23 SLA miniscrews and 24 MA miniscrews were placed into the distal femoral condyle of 24 New Zealand rabbits. Removal torque test and the BIC was histologically evaluated at 0 and 8 weeks. Results: There was no statistical difference between the RTV in the MA group versus the SLA group at both 0 and 8 weeks. Comparing 0–8 weeks, there was no significant difference in RTV of the SLA group ( P = 0.48), however the change in the MA group was statistically significant ( P = 0.006). Histological observation showed a significant decrease in BIC comparing 0 and 8 weeks for the MA group. The BIC ratio at 8 weeks was statistically significantly higher in the SLA group compared to the MA group. Conclusion: SLA surface preparation does not increase the RTV of miniscrews. Further investigations under loading and a large sample size are required.

Despite the importance of nickel and chromium release from orthodontic brackets, there are no in vivo or in vitro studies on this issue in the case of metal-injection molding (MIM) brackets.Saliva samples were collected from 30 orthodontic patients divided randomly into two groups of conventional and MIM brackets, before treatment and 2 months later. Approved attendees with odd and even numbers were, respectively, assigned to the control and treatment groups. For blinding, the patients were not informed of their bracket types, and the saliva samples were coded. Nickel and chromium levels were determined using atomic absorption spectrophotometry. Data were analysed using repeated-measures two-way analysis of covariance, independent-samples t-test, chi-squared, Spearman and point-biserial correlation coefficients, Mann-Whitney, and Wilcoxon tests (α = 0.05).Mean nickel level increased from 7.87±8.14 (pre-treatment) to 12.57±9.96 (2nd month) in the control group, and from 8.62±9.85 (pre-treatment) to 8.86±6.42 µg/l in the MIM group. Both of these increases were significant (Wilcoxon P0.03). Average chromium level changed from 0.25±0.56 (pre-treatment) to 0.35±0.62 and from 0.42±0.48 to 0.26±0.57 µg/l in the MIM group. Only the reduction observed in the MIM group was significant (Wilcoxon P = 0.0438). Age and gender had no significant influence on ion levels (P0.1). The differences between both ions' levels measured in the 60th day in both bracket groups were not significant (Mann-Whitney P0.05). The extents of changes over time were not significantly different between the bracket types (Mann-Whitney P0.05).The sample size was not predetermined based on power calculations. The spectrophotometer was limited to detecting chromium concentrations above 0.25 µg/l. Ion discharge from brackets might continuously change. The current in vivo methods are unable to take such fluctuations into account.Nickel might increase in patients undergoing treatment with both bracket types, although the rate of increase might be greater in patients under treatment with conventional brackets. Using MIM brackets might reduce salivary chromium for a trivial but generalizable amount. Still, ion levels leached from conventional versus MIM brackets might not show a difference after 2 months. Age and gender might not affect the ion levels in normal people or orthodontic patients.The protocol is registered offline at the university library.The protocol was not published before the trail commencement.Self-funded (S. H.).None to declare.

Summary Objective: To evaluate the ef fects of self-ligating bracket (SLB) type and vibration on frictional force and stick-slip phenomenon (SSP) in diverse tooth displacement conditions when a levelling/ alignment wire was drawn. Materials and Methods: A total of 16 groups were tested ( n = 10/group): Two types of SLBs [active SLB (ASLB, In-Ovation R) and passive SLB (PSLB, Damon Q)]; vibration (30 Hz and 0.25 N) and nonvibration conditions; and 4 types of displacement [2 mm lingual displacement of the maxillary right lateral incisor (LD), 2 mm gingival displacement of the maxillary right canine (GD), combination of LD and GD (LGD), and control]. After applying artificial saliva to the typodont system, 0.018 copper nickel– titanium archwire was drawn by Instron with a speed of 0.5 mm/min for 5 minutes at 36.5°C. Af ter static/kinetic frictional forces (SFF/KFF), and frequency/amplitude of SSP were measured, statistical analysis was performed. Results: ASLB exhibited higher SFF , KFF, and SSP amplitude (all P < 0.001) and lower SSF frequency (all P < 0.05) than PSLB in all displacement groups. Vibration decreased SFF, KFF, and SSP amplitude and increased SSP frequency in control and all displacement groups (all P

Objective: Comparison of three different retention strategies 5 years or more postretention. Design, Setting, and Participants: Randomized, prospective, single-centre controlled trial. Forty-nine patients (33 girls and 16 boys) were randomly assigned to one of three retention methods during 2 years by picking a ballot shortly before start of retention treatment. Inclusion criteria were no previous orthodontics, permanent dentition, normal skeletal sagittal, vertical, and transversal relationships, Class I dental relationship, space deficiencies, treatment plan with extractions of four premolars followed by fixed straight-wire appliance. Maxillary and mandibular Little's irregularity index (LII), intercanine and intermolar width, arch length, and overbite/overjet were recorded in a blinded manner, altogether 10 measurements on each patient. Significant differences in means within groups assessed by t -test and between groups by one-way analysis of variance. Interventions: Retention methods: removable vacuum-formed retainer (VFR) covering the palate and the maxillary anterior teeth from canine-to-canine and bonded canine-to-canine retainer in the lower arch (group V-CTC); maxillary VFR combined with stripping of the lower anterior teeth (group V-S); and prefabricated positioner (group P). Results: Maxillary mean LII ranged from 1.8 to 2.6mm, mean intercanine width 33.6–35.3mm with a significant difference between groups V-S and P, mean intermolar width 46.8–47.4mm and mean arch length 21.8–22.8mm. Mandibular mean LII ranged from 2.0 to 3.4mm with a significant difference between groups V-S and P, mean intercanine width from 25.4 to 26.6mm, mean intermolar width from 40.8 to 40.9mm and mean arch length from 16.9 to 17.3mm. Mean overbite ranged from 1.8 to 2.7mm and mean overjet from 3.7 to 4.1mm. Limitations: A single centre study could be less generalizable. Conclusions: The three retention methods disclosed equally favourable clinical results. Trial registration: This trial was not registered. Protocol: The protocol was not published before trial commencement.

Objective: To evaluate the stability and bone availability of the most distal (third) palatal ruga, as an anatomical region for safe insertion of orthodontic mini-implants (OMIs) in the anterior palate. Study design: Orthodontic records of 35 patients were analysed. Initial (T1) and final (T2) study models were bisected and the outline of the palatal contour was marked on the surface. Models were scanned and the palatal contours were superimposed on the palatal structures on the respective initial and final cephalometric images. Cephalometric measurements were used to assess vertical (3rdRug-PP, 2ndRug-PP, and 1stRug-PP), and oblique bone levels (3rdRug-U1, 2ndRug-U1, 1stRug-U1, and 3rdRug-U1(o)). Paired Student’s t -test was used to compare measurements between T1 and T2. Results: The position of the third palatal ruga remained stable during orthodontic treatment (Δ2ndRug-3rdRug P = 0.1mm; P = 0.61 and Δ1stRug-3rdRug P = 0.2mm; P = 0.39). Bone availability also remained adequate (3rdRug-U1T2 (o) = 9.9mm). Conclusion: The third palatal ruga is a reliable clinical landmark to evaluate bone availability for the placement of OMIs in the anterior palate.

Summary Objective: The aim of the study is to establish a stable animal model of obstructive sleep apnoea– h ypopnea syndrome (OSAHS) and assess the effectiveness of a mandibular advancement device (MAD). Materials and methods: Eighteen 6-month-old male New Zealand white rabbits were randomized into three groups according to intervention: Group OS AHS, Group MAD, and a control group (n = 6 for each group). Rabbits in Group OSAHS and Group MAD were established as OSAHS model by injection, at a dose of 2 ml hydrophilic polyacrylamide gel, in the submucous muscular layer of the sof t palate. Computed tomography (CT) and polysomnography (PSG) showed that OSAHS was developed successfully, the rabbits in Group MAD were fitted with the MAD and CT of the upper airway and PSG evaluated its effectiveness. Histological observation of the injection sites was conducted. Results: CT scans showed the reduced sagittal space and cross-sectional areas of retropalatal upper airway in Group OSAHS were corrected by MAD (upper airway space in Group MAD was similar to that in the control group). The rabbits in Group OSAHS developed obvious sleep apnoea and hypopnea in supine position, with increased apnoea–hypopnea index and decreased oxygen saturation (SaO 2 ). These were significantly improved by MAD and apnoea and hypopnea were not observed. Histology of the soft palate showed that the injected gel was entirely surrounded with connective tissues. Conclusion: We primarily developed an OSAHS and MAD therapy animal model with narrow oropharynx in upper airway which could be further available for OSAHS analysis.

Objectives: The aim of this study was to analyse the displacement and stress distribution in the maxillofacial complex during maxillary protraction with buccal and palatal plates using three-dimensional finite element analysis. Materials and methods: Three anchorage appliance models—palatal plate (Type A), miniplate at the infrazygomatic crest (Type B), and conventional tooth-borne appliance (Type C)—were designed and integrated into a skull model. Protraction force was 500g per side and force direction was forward and 30 degree downward to the maxillary occlusal plane. The stress distribution around the circum-maxillary sutures and the displacement of the surface landmarks were analysed. Results: All models showed forward and upward displacement at anterior nasal spine, Point A, and prosthion and forward and downward displacement at posterior nasal spine resulting in a counter-clockwise rotation. This anterior displacement was greatest in Type A. At the maxillary process of the zygoma, upward movement was shown only in Type A, whereas downward movement was observed in Types B and C. The greatest stresses in Type A were at the pterygomaxillary and the zygomaticotemporal sutures. Type B showed the greatest stress at the frontomaxillary suture. Limitations: Type A showed asymmetric results; however, it was not of clinical significance. Conclusion: The palatal plate resulted in wider stress distribution and more forward displacement compared to miniplate at the infrazygomatic crest area and conventional tooth-borne appliances. It might be recommended to consider the application of the palatal plate for maxillary protraction in Class III patients.

External root resorption (ERR) can be considered to be an important negative sequelae of orthodontic treatment as in severe cases it can have an impact on the long-term viability of the affected dentition. ERR is defined as either a physiologic or a pathologic process resulting in the loss of cementum and dentin in the dental roots (Blake et al. , 1995). The etiology of ERR appears multi-factorial in nature with numerous potential elements at play including, but not limited to, individual genetic factors and orthodontic mechanical or iatrogenic factors (Brezniak and Wasserstein, 1993) The orthodontic factors that are associated with ERR are complex and not fully understood. There exists a lack of agreement in the literature regarding the specific incidence of ERR (Weltman et al. , 2010). There is evidence that heavy forces are particularly harmful (Weltman et al. , 2010). Numerous studies have displayed a correlation between increased ERR and heavy orthodontic forces compared with light forces or controls (Chan and Darendeliler, 2004, 2006; Harris et al. , 2006; Barbagallo et al. , 2008). In both tension and compression force areas, direct heavy orthodontic forces have been shown to produce significantly more ERR than in regions under light compression and light tension forces (Chan and Darendeliler, 2006). However, there is a need for more evidence to identify those teeth/individuals at higher risk for ERR and to determine ways to manage its severity and prevalence in orthodontic patients (Weltman et al. , 2010). Historically, the in vivo detection of ERR has been mainly through the use of two-dimensional (2D) radiographs. There are geometric limitations associated with 2D imaging of a three-dimensional (3D) phenomenon; therefore, the quantitative value of 2D radiographs to measure ERR is questionable. (Sameshima and Sinclair, 2001; Chan and Darendeliler, 2004; Katona, 2006 …

SUMMarY ObJECtiv ES: the aim of this study was to investigate the effects of retraction force and anchorage reinforcement with orthodontic mini implants on occlusal force. MatEriaLS anD MEtHODS: a strain gauge was attached to the palatal surface of the maxillary right first molar on an en masse retraction model. rESULtS: Occlusal forces were measured from this model, according to different retraction forces that were generated by elastic chain, under varied compressive forces (simulating masticatory forces). this retraction experiment was then performed again, after using anchorage reinforcement with an orthodontic mini implant. Occlusal force decreased as retraction force increased. the decrease showed a significant difference above 150 g of retraction force (P

SUMMARY BACKgROUND: Orthodontic miniscrews placed in growing subjects often loosen during orthodontic treatment. The ability to place miniscrews, regardless of age, would be clinically beneficial. OBJECTIvES: To assess the effects of low-intensity pulsed ultrasound (LIPUS) on the stability of orthodontic miniscrews in growing rats. MATERIALS/METHODS: The mobility of miniscrews after placement was recorded and the miniscrew–bone inter face was examined histomorphometrically using tibiae of seven male Sprague-Dawley rats (aged 6 weeks). Field-emission scanning electron microscopic images were used to evaluate the bone–miniscrew interface, and a mobility test device was used to assess the stiffness of miniscrew placement. Fourteen custom-made miniscrews with 1.4 mm diameters and 4.0 mm lengths were placed in the right and left tibiae. LIPUS was used to stimulate right tibiae at the sites of miniscrew placement, and left tibiae were left untreated as controls. RESULTS: Significantly lower mobility was observed in the LIPUS-treated group compared with the control group (P < 0.05). Histomorphometric evaluation indicated that bone–miniscrew adhesion was significantly better in the LIPUS-treated group than in the control group (P

This study aimed to investigate the differences in the force loss during simulated archwire-guided canine retraction between various conventional and self-ligating brackets. Three types of orthodontic brackets have been investigated experimentally using a biomechanical set-up: 1. conventional ligating brackets (Victory Series and Mini-Taurus), 2. self-ligating brackets (SmartClip: passive self-ligating bracket, and Time3 and SPEED: active self-ligating brackets), and 3. a conventional low-friction bracket (Synergy). All brackets had a nominal 0.022″ slot size. The brackets were combined with three rectangular 0.019×0.025″ archwires: 1. Remanium (stainless steel), 2. Nitinol SE (nickel-titanium alloy, NiTi), and 3. Beta III Titanium (titanium-molybdenum alloy). Stainless steel ligatures were used with the conventional brackets. Archwire-guided tooth movement was simulated over a retraction path of up to 4mm using a superelastic NiTi coil spring (force: 1 N). Force loss was lowest for the Victory Series and SmartClip brackets in combination with the steel guiding archwire (35 and 37.6 per cent, respectively) and highest for the SPEED and Mini-Taurus brackets in combination with the titanium wire (73.7 and 64.4 per cent, respectively). Force loss gradually increased by 10 per cent for each bracket type in combination with the different wires in the following sequence: stainless steel, Nitinol, and beta-titanium. Self-ligating brackets did not show improved performance compared with conventional brackets. There was no consistent pattern of force loss when comparing conventional and self-ligating brackets or passive and active self-ligating brackets.

This study aimed to evaluate biomechanical behaviour of inclined orthodontic mini-implants by analyzing its insertion torque (IT), axial pull-out strength (APS), and cortical bone thickness in contact with mini-implant (CBTC). A total of 102 mini-implants were inserted at 90 degree, 60 degree, and 45 degree to the surface of synthetic bone. Peak IT was measured, and the mini-implants were aligned with the mechanical testing machine to record the APS. The cortical bone thickness in contact with each mini-implant was measured after the pull-out test and the data were subjected to statistical analyses. The 45 degree group had a significantly higher IT compared with the 90 degree group (P < 0.05). There was a statistically significant increase in the average of cortical bone thickness in CBTC across the three groups (P < 0.05). A negative correlation between the angulation and the CBTC (r = -0.95, P < 0.05) and a positive correlation between the APS and the CBTC were observed (r = 0.34, P < 0.05). Mini-implants that are inserted more inclined to the surface of the bone provide greater IT and an increased contact with the cortical bone. The greater the CBTC, the greater is the APS.

The purpose of this study was to compare the activation and deactivation forces generated during first-order archwire deflections when different sizes and types of NiTi wires are paired with conventional and self-ligating brackets (SLBs) and to evaluate the rotational control between these same archwire and bracket combinations. Four maxillary premolar SLBs (Damon 3MX, SmartClip, Carriere, and In-Ovation R) and one conventional twin bracket (Victory) were paired with seven archwires [0.014, 0.016, 0.018, 0.016 × 0.022 Ultra Therm (thermal A f 80-90°F), 0.016, 0.018 SPEED Supercable, and 0.017 × 0.025 Turbo]. A cantilever test design was used and 10 trials per bracket/archwire combination were performed. Load/deflection data were captured over 4 mm fi rst-order archwire deflections. Forces generated were compared across all bracket/archwire combinations. Among thermal archwires, for a given deflection, forces increased with increasing archwire size. Supercable archwires displayed less force than their same size thermal counterparts. The Turbo archwire generated force values in between those of 0.016 and 0.018 thermal archwires. Rotational control improved with increasing wire dimensions and for a given archwire size. Rotational control among brackets generally ranked as follows: In-Ovation R > SmartClip > Carriere and Damon 3MX.

Orthodontic torque expression is the result of axial rotation of rectangular archwires within a rectangular bracket slot. This study investigates the effect of bracket material on torque expression. Torque exerted by a rotating archwire on each bracket will be measured as well as the relative deformation of each bracket slot. A total of 60 tests were performed where archwires were rotated within a bracket slot to produce torque within a bracket. Thirty Ormco Orthos Ti and 30 Orthos SS were compared to investigate the effect of torque on bracket material. Each bracket was mounted on a six-axis load cell that measured forces and moments in all directions. The archwire was rotated from an initial angle of 0 degree in 3 degrees increments to maximum angle of 51 degrees and then returned to the initial position. An overhead camera took images at each 3 degrees increment. The bracket images were post-processed using a digital image correlation technique to measure the relative deformation of each bracket slot. The maximum torque expressed at 51 degrees was 99.8 Nmm and 93.0 Nmm for Orthos Ti and Orthos SS, respectively. Total plastic deformation measured at 0 degrees post-torquing of the Orthos SS was 0.038 mm compared to 0.013 mm for Orthos Ti. The Orthos Ti brackets plastically deformed less than the Orthos SS brackets after torquing. The Orthos SS bracket plastic deformation was 2.8 times greater than that of Orthos Ti brackets. The Orthos Ti brackets expressed more torque than the stainless steel brackets but exhibited substantial variation.

Orthodontic elastomeric modules are susceptible to degradation and deformation after time in the mouth. The aims of this study were to determine whether degradation of elastomeric modules significantly affects friction during sliding mechanics and to investigate whether there is a difference in the behaviour of elastomeric modules after storage in both in vivo and in vitro environments. An Instron testing machine was used to determine the friction generated by elastomeric modules on 0.019 × 0.025 inch stainless steel archwires at 4 degrees of bracket tip. Four brands of modules were tested straight from the packet (n = 15), after storage in artificial saliva (n = 15), and after being in patients' mouths (n = 32). Modules were tested after 24 hours, 1 week, and 6 weeks after storage in both in vivo and in vitro. Analysis of variance revealed that the degradation of elastomeric modules had a variable affect upon friction and that each storage medium produced a distinct pattern of frictional resistance. Modules stored in artificial saliva experienced a significant reduction in friction (P < 0.001) while modules collected from patients' mouths produced similar friction to modules tested straight from the packet. TP Super Slick® modules under dry test conditions produced significantly greater friction than the other three types of test modules (P < 0.001). The structure and surface characteristics of elastomeric modules may affect frictional resistance when a bracket slides along an archwire. These effects vary according to time, storage medium, and brand of elastomeric material.

The aim of this prospective study was to evaluate and compare stability after 6 months of Essix retainer use. Patients' perceptions of wearing the retainer were also evaluated. A total of 69 patients, 53 girls and 16 boys [mean age 15.7 years, standard deviation (SD) 1.96], were included in the study and randomized into two groups with different wear regimens; full-time wear for 3 months and thereafter at night (group A) compared to full-time wear for 1 week and thereafter at night only (group B). Sixty patients completed the study and thus, group A comprised 30 maxillary retainers and 18 mandibular retainers and group B 30 maxillary and 18 mandibular retainers. Little's irregularity index (LII), overjet, and overbite were measured at debond (T(1)) and after 6 months (T(2)). Differences within and between groups were analysed with a Mann-Whitney test. At T(2), all patients completed a questionnaire in order to evaluate their experience of wearing an Essix retainer and how they complied with the given instructions. Differences in LII during T(1)-T(2) were 0.44 and 0.49 mm for group A and B, respectively, but with no significant difference between the groups. There were also no significant changes in overjet and overbite within or between the groups during T(1)-T(2). According to the responses to the questionnaire, the retainer was well tolerated by the patients. It was therefore concluded that the Essix retainer is sufficient for maintaining the results after orthodontic treatment and that night-time wear is adequate.

The purpose of this study was to evaluate the effect of reverse pull headgear (RPHG) in the treatment of Class III malocclusions in the late mixed and early permanent dentition and its long-term stability at the time when facial growth was close to completion. The treatment group comprised 22 subjects (12 males and 10 females, mean age: 11.38 ± 0.69 years). The control group included 17 subjects (7 males and 10 females, mean age: 11.54 ± 1.07 years). The mean RPHG treatment time was 1.5 ± 0.95 years and the observation time for the control group was 1.75 ± 0.83 years. For each subject, lateral cephalograms were obtained before (T1) and after (T2) treatment or observation. These cephalograms were traced and analyzed and the differences between T1 and T2 values were examined with paired t-tests. Of the 22 treated cases, 10 patients were followed up until at the mean age of 16.18 years (T3). Since there was no relapse in anterior crossbite, the long-term effects of RPHG were evaluated by measuring the maxillary and mandibular skeletal changes. The follow-up patients were divided into two groups based on the change in ANB: a stable group (decrease in ANB2 degrees) and an unstable group (decrease in ANB2 degrees). The skeletal effects of RPHG in treating Class III anomalies just before or at the beginning of the pubertal growth spurt include protraction of the maxilla and dentition and inhibition of forward growth of the mandible. With regard to the long-term change, a slight alteration in the position of the maxilla and in the position and growth direction of the mandible resulted in a slight decrease in ANB in the stable group. The slight retrusion in the maxilla, combined with the significant protrusion in the mandible and the more horizontal mandibular growth direction, resulted in a decrease in ANB in the unstable group. This indicated that the maxilla remained relatively stable and that the unstable factor was continuing mandibular growth during the pubertal and post-pubertal period. For patients with an excessive mandible, orthopaedic therapy should start at the beginning of pubertal growth and orthodontic fixed appliance should follow immediately after RPHG so that mandibular growth in the sagittal direction during puberty or even after pubertal growth may be effectively inhibited.

Oral appliances (OAs) are increasingly advocated as a treatment option for obstructive sleep apnoea (OSA). However, it is unclear how their different design features influence treatment efficacy. The aim of this research was to systematically review the evidence on the efficacy of different OAs on polysomnographic indices of OSA. A MeSH and text word search were developed for Medline, Embase, Cinahl, and the Cochrane library. The initial search identified 1475 references, of which 116 related to studies comparing OAs with control appliances. Among those, 14 were randomized controlled trials (RCTs), which formed the basis of this review. The type of OA investigated in these trials was mandibular advancement devices (MADs), which were compared with either inactive appliances (six studies) or other types of MADs with different design features. Compared with inactive appliances, all MADs improved polysomnographic indices, suggesting that mandibular advancement is a crucial design feature of OA therapy for OSA. The evidence shows that there is no one MAD design that most effectively improves polysomnographic indices, but that efficacy depends on a number of factors including severity of OSA, materials and method of fabrication, type of MAD (monobloc/twin block), and the degree of protrusion (sagittal and vertical). These findings highlight the absence of a universal definition of treatment success. Future trials of MAD designs need to be assessed according to agreed success criteria in order to guide clinical practice as to which design of OAs may be the most effective in the treatment of OSA.

Friction between archwires and labial brackets has received considerable attention; however, information on the frictional behaviour of commercially available lingual brackets is limited. The aim of this study was to investigate the frictional resistance resulting from a combination of lingual orthodontic brackets (7th Generation, STb, Magic, and In-Ovation L) and stainless steel archwires at 0, 5, and 10 degrees of second-order angulation. Each bracket type (n = 30) was tested with three different sizes of archwires. Static and kinetic frictional forces were evaluated with a universal testing machine. Statistical analysis of the data was performed with non-parametric Kruskal-Wallis and Dunn's multiple comparison tests. All tested brackets showed higher frictional forces as the wire size and second-order angulation increased. The lowest friction was found with In-Ovation L brackets and 0.016 inch archwires at 0 degrees angulation, and the greatest friction with a combination of STb brackets and 0.017 × 0.025 inch archwires at 10 degrees angulation. For all combinations, Magic and In-Ovation L brackets showed lower frictional resistance when compared with 7th Generation and STb brackets. The slot width (occluso-gingival dimension) of the brackets, measured using the optics of a microhardness machine, showed that all brackets were oversized and that Magic brackets had the largest slot width. Surface roughness of the brackets investigated using atomic force microscopy and scanning electron microscopy, demonstrated that the 7th Generation brackets had the greatest surface roughness.

The purpose of this retrospective study was to elucidate potential confounding factors affecting initial stability of miniscrews inserted to enhance orthodontic anchorage. Four hundred and seven miniscrews inserted in 168 patients treated by 17 orthodontic residents were analysed in a consecutive chart review. The outcome variable was the stability of the miniscrew, measured as a dichotomous variable, 0 if the miniscrew loosened during a 1 week period after insertion to the time of orthodontic force application and a value of 1 otherwise. Potential confounding variables examined were gender, age, jaw, insertion site, tissue type, length and diameter of the miniscrew, and number of previous insertions. Generalized estimating equations (GEE) methods were used to estimate the influence of each factor on stability for the correlated binary outcomes of each patient. A weighted analysis for the GEE approach was also performed for the convergence calculation of the estimation procedure due to a value of 0 in one of the cells. Crude odds ratio (cOR) and adjusted odds ratio (aOR) and their 95 per cent confidence intervals (CI) were calculated for this purpose. The overall success rate after 1 week was 93.1 per cent (379/407). The screws inserted by more experienced clinicians (more than 20 miniscrews) were found to have approximately a 3.6-fold higher success rate of initial stability compared with those inserted by less experienced clinicians after adjusting for the insertion site (aOR = 3.63, P = 0.015). The results of the present study suggest that the initial stability depends on insertion site and clinician experience.

The aim of this study was to investigate the morphological features and distribution of biofilms on Invisalign orthodontic appliances, in a sample of 'slow' and 'fast' plaque formers using scanning electron microscopy (SEM). Fifty-six Chinese male/female volunteers (aged 19-39 years) were screened for their plaque-forming rate using the plaque percentage index (PPI) coupled with digital photography and computer-based image analysis, after a period of 48 hours of abstinence from oral hygiene procedures. Eleven volunteers (seven males/four females) representing the lowest and highest ends of the plaque formation spectrum were chosen as slow and fast plaque formers, respectively. The subjects wore a full-coverage splint appliance, in which four tiles of Invisalign material were embedded. These tiles were collected at intervals of 1, 3, 6, 12, 24, and 48 hours, as well as 3, 7, and 14 days, immediately fixed in 10 per cent paraformaldehyde in 0.2 M cacodylate buffer solution and prepared for SEM. The surface configuration of the Invisalign appliance was visualized, as well as the chronological pattern of biofilm formation. Significance between fast and slow plaque formers was determined using a Student's t-test. Colonization appeared to centre initially on the raised edges or textured surfaces of the appliance, and initial adhesion was quicker and more abundant in the fast plaque-forming group. In the later stages of biofilm development, both groups showed no discernible differences in biofilm accrual on the surfaces, but the fast group displayed a more complex biofilm structure. More recessed and sheltered areas of the appliance, such as the cusp tips and attachment dimples, harboured more biofilm than the flat surfaces. Hence, it seems that the novel Invisialign orthodontic appliance is a useful tool to investigate the features of biofilm formation in time-course studies.

The aim of the present morphometric investigation was to evaluate the effects of bone-anchored maxillary protraction (BAMP) in the treatment of growing patients with Class III malocclusion. The shape and size changes in the craniofacial configuration of a sample of 26 children with Class III malocclusions consecutively treated with the BAMP protocol were compared with a matched sample of 15 children with untreated Class III malocclusions. All subjects in the two groups were at a prepubertal stage of skeletal development at time of first observation. Average duration of treatment was 14 months. Significant treatment-induced modifications involved both the maxilla and the mandible. The most evident deformation consisted of marked forward displacement of the maxillary complex with more moderate favourable effects in the mandible. Deformations in the vertical dimension were not detected. The significant deformations were associated with significant differences in size in the group treated with the BAMP protocol.

SUMMARY This study compared peak insertion torque values of six commercially available self-drilling mini-implants [Mini Spider® screw (1.5 × 8 mm), Infinitas® (1.5 × 9 mm), Vector TAS® (1.4 × 8 mm), Dual Top® (1.6 × 8 mm), Tomas Pin® (1.6 × 8 mm), and Ortho-Easy® (1.7 × 6, 8, and 10 mm)]. Twenty implants each were drilled into acrylic rods at a speed of 8 rpm using a motorized torque measurement stand, and the values were recorded in Newton centimetres (Ncm). A further 20 Ortho-Easy® implants with a length of 6 and 10 mm were tested at 8 rpm; 20 implants of 6 mm length were also tested at 4 rpm. Kaplan–Meier estimates of the peak torque values were compared using the log-rank test with multiple comparisons evaluated by Sidak’s test. There were significant differences in the maximum torque values for different mini-implants with the same length. The Mini Spider® screw and Infinitas® showed the lowest average torque values (6.5 and 12.4 Ncm) compared with Vector TAS®, Dual ToP®, Tomas Pin®, and Ortho-Easy® (30.9, 29.4, 25.4, and 24.8 Ncm, respectively). There was no correlation between the diameter of the implants and torque values. The Tomas Pin® showed the largest standard deviation (7.7 Ncm) and the Dual Top® implant the smallest (0.6 Ncm). Different insertion speeds did not result in significant differences in peak torque values but the 6 mm mini-implants showed significantly higher torque values than the 8 and 10 mm implants. Using a ‘torque limiting’ screwdriver or pre-drilling cortical bone to reduce insertion, torque appears justified for some of the tested implants.

Mini-implants are widely utilized as anchorage units in orthodontic treatment. Nevertheless, there are factors that interfere with their clinical performance. The aim of this study was to examine the impact of length and diameter on the primary stability of two different types of orthodontic mini-implants loaded with two force levels. A total of 90 self-drilling mini-implants were inserted in bovine ribs in vitro, 62 of which were used in data analysis. The mini-implants were of two types, Aarhus (n=29) and Lomas (n=33), of two lengths (7 and 9 mm, n=26 and n=28, respectively), and of two diameters (1.5 and 2 mm, Lomas only, n=6 and n=8, respectively). A closed nickel-titanium (NiTi) coil spring was attached to each mini-implant. Half of the preparations were loaded with a low force of 0.5 N and the other half with a force of 2.5 N. Mini-implant deflections during force application were non-invasively registered using a three-dimensional (3D) laser-optical system. The results were analysed with analysis of variance for the effects of implant type, implant length, and force level, and with a t-test for the study of the effect of diameter in two different diameter variants of the same (Lomas) implant. In the low-force group, implant displacements were not statistically significant difference according to the investigated parameters. In the high-force group, the 9 mm long mini-implants displaced significantly less (10.5±7.5 μm) than the 7 mm long (22.3±11.3 μm, P

The purpose of this study was to compare the effects of a differently designed functional appliance (the R-appliance) with a twin-block (TB)-treated group. Thirty patients (18 girls and 12 boys) with a mean age of 10.5 ± 0.7 years were treated with the R-appliance for 16.2 ± 0.3 months and 25 (11 boys and 14 girls) with a mean age of 11.2 ± 1.3 years with a TB for 16.1 ± 1.4 months (control). All had a Class II division 1 malocclusion due to mandibular deficiency. Lateral cephalograms obtained at the beginning (T1) and end (T2) of the study were analysed. Paired t -tests showed that SNB significantly increased in both groups. The incisor mandibular plane angle (IMPA) was reduced in the R-appliance group by 1.9 ± 4.9 degrees ( P < 0.04) but increased by 0.5 ± 5.1 degrees ( P < 0.6) in the TB group. SNA in the R-appliance group showed an increase of 0.2 ± 1.8 degrees ( P < 0.5), while it was decreased by 0.2 ± 1.3 degrees ( P < 0.3) in the TB group. Both treatment modalities were successful in moving the mandible forward. However, with the R-appliance, this was achieved without retroclination of the lower incisors.

SUMMARY This study compared the moments produced by V-bends placed in rectangular nickel titanium (NiTi) orthodontic wire to those produced in titanium–molybdenum alloy (TMA). V-bends that included angles of 135, 150, and 165 degrees were heat set into 0.017 × 0.025 and 0.016 × 0.025 inch NiTi alloy wires and identical bends bent into TMA wires with a dimension of 0.018 × 0.025 and 0.016 × 0.022 inch. There were five specimens per group ( N = 60). The moments produced by each specimen were tested on a custom jig that aligned two lower incisor brackets with zero tip or torque at an interbracket distance of 15 mm. The upper bracket was connected to a moment transducer. The V-bend position for each specimen was varied in 1 mm increments towards the moment transducer. The moments produced by TMA wires were linear, which increased as the V-bend approached the transducer, while NiTi exhibited a non-linear curve characterized by a flattening of the moment value. The point of dissociation (where the moment experienced by the bracket became zero) was estimated for both wire types using linear mixed model analysis. For TMA wires, this point was similar to that reported in the literature but was significantly less for NiTi wire when compared with TMA. The moments produced by TMA generally increased with the magnitude of the V-bend, whereas this was not the case for NiTi.

SUMMARY The aim of this study was to investigate, over a period of approximately 3 years, the reactions to orthodontic loading of a type V titanium miniscrew. In this retrospective study, conducted in a private practice, the records of 300 miniscrews inserted in 132 consecutive patients (80 females, 60.6 per cent) by the same surgeon were evaluated. The mean age of the patients was 23.2 years. Three types of miniscrews (type A: diameter 1.5 mm, length 9 mm; type B: diameter 1.5 mm, length 11 mm; and type C: diameter 1.3 mm, length 11 mm) were used. The clinical variables evaluated included the loading time and location of the miniscrew in relation to the gingiva and root. The success rates with different variables were compared using chi-square or Fisher’s exact test where appropriate. A cumulative survival rate of 81 per cent (243/300) was found using Kaplan–Meier analysis, with an optimum success rate for the 1.3 mm wide miniscrew inserted in the attached gingiva, with immediate loading applied. Cox proportional hazard regression showed significant differences between success rate and the following parameters: gender, loading time, gingival or bone localization, and diameter of the miniscrews. Considering the clinically controllable parameters, and within the limits of this retrospective study, 1.3 mm diameter miniscrews inserted in attached gingiva and immediately loaded had the most favourable prognosis.