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Transient inflammatory surface resorption, referred to as orthodontic induced inflammatory root resorption (OIIRR), is an iatrogenic consequence of orthodontic tooth movement. Systemic fluoride has been associated with a reduction of OIIRR. This study aimed to investigate the effects of water fluoridation levels on OIIRR in a clinically applicable human orthodontic model.Twenty-eight patients who required bilateral maxillary first premolar extraction as part of orthodontic treatment were selected from 2 cities with high and low water fluoridation of ≥2 ppm and ≤0.05 ppm, respectively. Patients were separated into high fluoride (HF) and low fluoride (LF) groups on the basis of water fluoridation levels. Bilateral maxillary first premolar teeth were subjected to 150 g of buccal tipping forces for 12 weeks with reactivation every 4 weeks. Teeth were extracted at the end of 12 weeks. Root resorption crater volume was determined using microcomputed tomography and 3-dimensional reconstruction.HF group showed significantly less mean root resorption volume on the palatal root surface when compared with the LF group (P = 0.025). This difference was specifically displayed at palatal apical regions (P = 0.041). When root resorption volumes from the zones of orthodontic pressure (buccal cervical, palatal apical) were combined, the mean difference between HF and LF groups was statistically significant (P = 0.045).Findings of the present study indicated a positive correlation between water fluoridation and the reduction of OIIRR, especially at the zones of orthodontic pressure, using a clinically relevant human orthodontic model.

INTRODUCTION This split-mouth trial aimed to examine the effects of light-emitting diode (LED)-mediated photobiomodulation compared with no photobiomodulation on maxillary canine distalization. METHODS Twenty participants (10 males and 10 females; aged 11-20 years) requiring bilateral extraction of maxillary first premolars were included from the Sydney Dental Hospital waiting list. After premolar extractions, leveling, and alignment, canines were retracted on 0.020-in stainless steel wires with coil springs delivering 150 g of force to each side. Each patient's right side was randomly assigned to experimental or control using www.randomisation.com, and allocation concealment was performed with sequentially numbered, opaque, sealed envelopes. The experimental side received 850 nm wavelength, 60 mW/cm2 power, continuous LED with OrthoPulse device (Biolux Research Ltd, Vancouver, British Columbia, Canada) for 5 min/d. For the control side, the device was blocked with opaque black film. Patients were reviewed at 4-week intervals for force reactivation and intraoral scanning over 12 weeks. The primary outcome was the amount of tooth movement, and secondary outcomes were anchorage loss and canine rotation, all measured digitally. Blinding for study participants and the treating clinician was not possible; however, blinding was done for the measurements by deidentifying the digital scans. Linear mixed models were implemented for the data analysis. RESULTS Nineteen participants concluded the study. Data analysis showed that the treatment × time interaction was not significant, suggesting no difference in space closure (unstandardized regression coefficient [b], 0.12; 95% confidence interval [CI], -0.05 to 0.29; P = 0.17), canine rotation (b, 0.21; 95% CI, -0.82 to 1.25; P = 0.69), and anchorage loss (b, -0.01, 95% CI, -0.28 to 0.26, P = 0.94). No harms were noted. CONCLUSIONS Daily 5-minute application of LED did not result in clinically meaningful differences during extraction space closure compared with no LED application. REGISTRATION Australian New Zealand Clinical Trials Registry (ACTRN12616000652471). PROTOCOL The protocol was not published before trial commencement. FUNDING This research was funded by the Australian Society of Orthodontists Foundation for Research and Education.

Introduction The purpose of this 2-arm-parallel split-mouth trial was to investigate the effect of low-level laser therapy (LLLT) on the repair of orthodontically induced inflammatory root resorption (OIIRR). Methods Twenty patients were included in this study, with 1 side randomly assigned to receive LLLT, and the other side served as a sham. Eligibility criteria included need for bilateral maxillary first premolar extractions as part of fixed appliance treatment. OIIRR was generated by applying 150 g of buccal tipping force on the maxillary first premolars for 4 weeks. After the active force was removed, the teeth were retained for 6 weeks. LLLT commenced with weekly laser applications using a continuous beam 660-nm, 75-mW aluminum-gallium-indium-phosphorus laser with 1/e2 spot size of 0.260 cm2, power density of 0.245 W/cm2, and fluence of 3.6 J/cm2. Contact application was used at 8 points buccally and palatally above the mucosa over each tooth root for 15 seconds with a total treatment time of 2 minutes. After 6 weeks, the maxillary first premolars were extracted and scanned with microcomputed tomography for primary outcome OIIRR calculations. Subgroup analysis included assessment per root surface, per vertical third, and sites of heaviest compressive forces (buccal-cervical and palato-apical). Randomization was generated using www.randomization.com , and allocation was concealed in sequentially numbered, opaque, sealed envelopes. Blinding was used for treatment and outcome assessments. Two-tailed paired t tests were used to determine whether there were any statistically significant differences in total crater volumes of the laser vs the sham treated teeth. Results Total crater volumes were 0.746 mm3 for the laser treated teeth and 0.779 mm3 for the sham. There was a mean difference of 0.033 ± 0.39 mm3 (95% CI, −0.21 to 0.148 mm3) greater resorption crater volume in the sham group compared with the laser group; this was not statistically significant (P = 0.705). No harm was observed. Conclusions: No significant difference was found between LLLT and sham control groups in OIIRR repair.

Introduction Studies have demonstrated the potential efficacy of micro-osteoperforations in accelerating tooth movement by amplifying the expression of inflammatory markers. The aim of this investigation was to examine the effects of micro-osteoperforations on orthodontic root resorption with microcomputed tomography. Methods This prospective controlled clinical trial involved 20 subjects requiring extraction of the maxillary first premolars as part of their orthodontic treatment. A buccal tipping force of 150 g was applied to both premolars. Using the Propel appliance (Propel Orthodontics, San Jose, Calif), micro-osteoperforations were applied at a depth of 5 mm on the mesial and distal aspects in the midroot region of the experimental side of the first premolar root; the contralateral side served as the control. After 28 days, both premolars were extracted. The teeth were scanned under microcomputed tomography, and the volumes of root resorption craters were calculated and compared. Results Premolars treated with micro-osteoperforation exhibited significantly greater average total amounts of root resorption than did the control teeth (0.576 vs 0.406 mm3). The total average volumetric root loss of premolars treated with micro-osteoperforation was 42% greater than that of the control teeth. Conclusions This 28-day trial showed that micro-osteoperforations resulted in greater orthodontic root resorption. However, these results should be verified in patients who are undergoing full-length orthodontic treatment.

This study was a cephalometric evaluation of the growth changes in untreated subjects with minimal overbite at 4 time points during 4 developmental stages from the early mixed dentition to the permanent dentition, as well as from the prepubertal phase to young adulthood.A sample of 24 untreated subjects with minimal overbite (1.5 mm) was selected retrospectively from the University of Michigan Growth Study and the Denver Child Growth Study. The sample was followed longitudinally from about 9 years of age through 17 years of age. Dentofacial changes at the 4 times (T1-T4), defined by the cervical vertebral maturation method, were analyzed on lateral cephalograms. Nonparametric statistical analysis was used for comparisons.Overbite on average increased by 2.3 mm during the overall observation period. Improvement occurred during the prepubertal interval (T1-T2; 2.4 mm), whereas no significant changes occurred in the pubertal and postpubertal stages. From prepubertal ages to young adulthood, the open-bite tendency improved in 91% of the subjects, with self-correction in 75%. Logistic regression analysis on the cephalometric variables at T1 with the value of overbite at T4 did not show a statistically significant correlation.Subjects with an open-bite tendency show improvement of their occlusal condition during the prepubertal stage, but there is no significant improvement after this. These results provide useful indications for appropriate orthodontic treatment timing for patients with an open-bite tendency.

The purpose of this prospective study was to evaluate the dentoskeletal effects of a new magnetic functional appliance, the Sydney Magnoglide (Macono Orthodontic Lab, Sydney, Australia), after both active treatment with the appliance and comprehensive fixed appliance therapy, compared with a group of untreated Class II controls.Thirty-four consecutively treated Class II Division 1 patients treated with the Sydney Magnoglide followed by fixed appliances were compared with 30 untreated Class II controls with the same initial dentoskeletal Class II features and matched for age and sex. Lateral cephalograms were taken before treatment, immediately after functional appliance therapy, and after comprehensive fixed appliance therapy. Cephalometric analyses included the Pancherz analysis and linear and angular measurements. The comparisons were made with Student t tests (P 0.05). There were 3 dropouts, for a final sample for statistical analysis of 31 subjects.There was no statistically significant difference between the treated and control groups before treatment. Treatment with the Sydney Magnoglide and comprehensive fixed appliance therapy normalized the overjet and corrected the Class II relationship in all treated subjects. The ANB angle showed a reduction of 1.0°, as opposed to an increase of 0.3° in the untreated controls, and was associated with a statically significant improvement in the SNB angle (P 0.05). There was a significant gain of 2.3 mm in mandibular length in the treated group compared with the control group (P 0.01).The outcomes of this prospective study demonstrate that the compliance-free Sydney Magnoglide is an effective functional appliance for Class II correction.

Introduction: The effect of zoledronic acid, a potent and novel bisphosphonate, on tooth movement and orthodontically induced root resorption in osteoporotic animals systemically treated with zoledronic acid as similarly used in postmenopausal patients has not been elucidated. Therefore, this study was undertaken. Methods: Fifteen 10-week-old female Wistar rats were divided into 3 groups: ovariectomy, ovariectomy + zoledronic acid, and control. Only the ovariectomy and ovariectomy + zoledronic acid groups underwent ovariectomies. Two weeks after the ovariectomy, zoledronic acid was administered only to the ovariectomy + zoledronic acid group. Four weeks after the ovariectomy, 25-g nickel-titanium closed-coil springs were applied to observe tooth movement and orthodontically induced root resorption. Results: There were significant differences in the amounts of tooth movement and orthodontically induced root resorption between the ovariectomy and the control groups, and also between the ovariectomy and the ovariectomy + zoledronic acid groups. There was no statistically significant difference in tooth movement and orthodontically induced root resorption between the ovariectomy + zoledronic acid and the control groups. Zoledronic acid inhibited significantly more tooth movement and significantly reduced the severity of orthodontically induced root resorption in the ovariectomized rats. The ovariectomy + zoledronic acid group showed almost the same results as did the control group in both tooth movement and orthodontically induced root resorption. Conclusions: Zoledronic acid inhibits excessive orthodontic tooth movement and also reduces the risk of severe orthodontically induced root resorption in ovariectomized rats., American Journal of Orthodontics and Dentofacial Orthopedics, 141(5), pp.563-573; 2012

colak, canan/0000-0002-5289-1787; Elekdag-Turk, Selma/0000-0002-2799-6501; Darendeliler, Mehmet Ali/0000-0002-8906-8153 WOS: 000297994200006 PubMed: 22133964 Introduction: Microcomputed tomography offers a unique opportunity to accurately examine orthodontically induced inflammatory root resorption. The aims of this study were to quantify, in 3 dimensions, the amount of root resorption caused by placing heavy and light distal root tipping forces on premolars and to compare the prevalence of root resorption in different areas of the tooth. Methods: Thirty maxillary first premolars from 15 patients who were to have these teeth extracted as part of their orthodontic treatment were selected for this study. Each tooth in the same patient was randomly chosen to have either a 2.5 degrees or a 15 degrees distal root tipping bend placed for 4 weeks. After the experimental period, the teeth were extracted according to a strict protocol to prevent damage to the root. They were then imaged by a microcomputed tomography scan x-ray system (SkyScan 1172, SkyScan, Aartselaar, Belgium) and analyzed by software designed for volumetric measurements. Results: A significant difference was found in the amount of total root resorption between light and heavy forces (P = .021). The mean cube root volumes of the resorption craters in the 15 degrees tip-bend group were greater than in the 2.5 degrees tip-bend group. This significance was lost when the tooth was divided into vertical thirds, although a trend was still present. When the areas of expected compression in the periodontal ligament were compared with the areas of expected tension, significance was seen in the apical and cervical thirds only. Conclusions: Based on this experiment, one can conclude that a 15 degrees distal root tip bend causes more orthodontically induced inflammatory root resorption than a 2.5 degrees distal root tip bend. Furthermore, greater root resorption was found in areas under pressure when compared with areas under tension. (Am J Orthod Dentofacial Orthop 2011;140:e299-e305)

colak, canan/0000-0002-5289-1787; Darendeliler, Mehmet Ali/0000-0002-8906-8153; Elekdag-Turk, Selma/0000-0002-2799-6501 WOS: 000288982500010 PubMed: 21457842 Introduction: Root resorption is an undesirable consequence of orthodontic tooth movement. The severity is unpredictable, and, despite extensive research, the etiology remains unknown. Torque has been acknowledged as a risk factor for root resorption. The aims of the study were to evaluate and quantify the extent of root resorption after the application of 2.5 degrees and 15 degrees of buccal root torque for 4 weeks. Methods: Fifteen patients requiring bilateral extraction of their maxillary first premolars for orthodontic treatment were recruited to the study. By using a standardized experimental protocol, the right and left premolars were randomly subjected to either 2.5 degrees or 15 degrees of buccal root torque. At the end of the 4-week experimental period, the premolars were extracted. A volumetric analysis of root resorption was performed by using microcomputed tomography and measured with specially designed software. Results: Overall, the amounts of root resorption were comparable after the application of 2.5 degrees or 15 degrees of buccal root torque (P = 0.59). There was a significant difference between the 2 force levels only at the apical region (P = 0.034). More root resorption occurred in areas of compression than in areas of tension. The variables of age and sex were not statistically significant. Conclusions: Root resorption was evident after 4 weeks of buccal root torque application. More root resorption was seen at the apical region than at the middle and cervical regions. Higher magnitudes of torque might cause more root resorption, particularly in the apical region. As shown in previous studies, the etiology of root resorption is multi-factorial and cannot be explained by mechanical factors alone. (Am J Orthod Dentofacial Orthop 2011;139:e353-e360) Australian Society of Orthodontics Foundation for Research and Education; Australian Dental Research Foundation Supported by the Australian Society of Orthodontics Foundation for Research and Education and the Australian Dental Research Foundation.

Orthodontic treatment with clear sequential removable thermoplastic appliances (TAs) is gaining popularity as an alternative to treatment with fixed appliances. The amount of orthodontically induced inflammatory root resorption generated by such appliances has not been investigated. In this prospective randomized clinical trial, we used x-ray microtomography to quantify resorption generated by treatment with ClearSmile appliances (ClearSmile, Woollongong, Australia) and compared the effects with those of heavy and light conventional orthodontic forces and no force.The sample consisted of 54 maxillary first premolars in 27 patients who required bilateral extractions as part of their planned orthodontic treatment. The subjects were randomly assigned to 3 groups, each with 9 subjects. A split-mouth design was used, and forces were applied to the first premolars. In group 1, TAs were used to move teeth on 1 side in a buccal direction at a rate of 0.5 mm every 2 weeks (TA movement); the contralateral teeth were not moved and served at controls. In group 2, TA movement was used on 1 side. A buccal force of 225 g from a beta-titanium alloy cantilever spring (heavy force) was used on the contralateral side. In group 3, TA movement was used on 1 side. A buccal force of 25 g from a cantilever spring (light force) was used on the contralateral side. The treatment duration was 8 weeks (56 days +/- 1 day). The TAs were changed every 14 days, and each patient used 4 appliances. The springs were not reactivated. At the end of the study period, the teeth were extracted according to a strict protocol to prevent root damage. Resorption was measured with an x-ray microtomograph (1072, SkyScan, Aartselaar, Belgium). Software analysis determined quantity, location, and distribution of root resorption craters.The control teeth had the least amount of resorption. The light-force teeth had approximately 5 times more resorption than the control teeth (P.001). The TA teeth had similar but slightly greater resorption than the light-force teeth, or approximately 6 times greater than the control teeth (P.001). The heavy-force teeth had the most resporption, about 9 times greater than the controls (P.001).Clear removable TAs have similar effects on root cementum as light (25 g) orthodontic forces with fixed appliances.

Mandibular advancement splints (MAS) are a recognized therapeutic option in the treatment of obstructive sleep apnea (OSA). This study aimed to investigate side effects and possible changes in the dentofacial complex associated with long term use of MAS.The sample included 64 patients with OSA who had been using MAS on average for 25.1 +/- 11.8 months (range, 10.7-64.5 months). A specifically designed questionnaire was used to investigate the patients' self-assessment of the side effects of wearing MAS; cephalometric analyses and dental cast measurements were conducted to identify objectively dental and skeletal changes caused by MAS over time.The most commonly reported side effects were jaw discomfort, tooth tenderness, excessive salivation, and dry mouth. Subjectively, snoring improved in 56 patients (88%), and daytime sleepiness (Epworth sleepiness scale) scores significantly decreased from pretreatment to follow-up (11.4-7.1, P.001). Small subjective occlusal changes were experienced by 8 patients (12.5%). Reductions in overbite (-0.3 +/- 0.08 mm, P.01) and overjet (-0.2 +/- 0.06 mm, P.05) were found, and cephalometric analysis showed statistically significant but clinically insignificant changes limited to anterior movement of the mandibular incisors (0.5 +/- 0.12 mm, P.001).Side effects of MAS use over long periods are common but mild and well tolerated by most patients, and dentofacial changes are negligible.

Introduction: Intrusion is a critical type of orthodontic tooth movement in relation to external root resorption. Our aims in this prospective randomized clinical trial were to quantify, 3 dimensionally, the amount of root resorption when controlled light and heavy intrusive forces were applied to human premolars and to establish the sites where root resorption is more prevalent. Methods: Fifty-four maxillary first premolars, orthodontically indicated for extraction from 27 patients (left and right maxillary first premolars from each), were intruded for 28 days with buccal and palatal beta-titanium-molybdenum alloy 0.017 × 0.025-in cantilever springs. The patients were randomly divided into 3 groups, and various levels of force were used: group 1, heavy force (225 g) on 1 side and control force (0 g) on the contralateral side; group 2, light force (25 g) on 1 side and control force (0 g) on the contralateral side; group 3, light force (25 g) on 1 side and heavy force (225 g) on the contralateral side. After the experimental period, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed by using a microcomputed tomography scan x-ray system (SkyScan-1072, Skyscan, Aartselaar, Belgium) and specially designed software for direct volumetric measurements. Results: The volume of the root resorption craters after intrusion was found to be directly proportional to the magnitude of the intrusive force applied. The results showed that the control group had fewer and smaller root resorption craters, the light force group had more and larger root resorption craters than the control group, and the heavy force group had the most and the largest root resorption craters of all groups. A trend of linear increase in the volume of the root resorption craters was observed from control to light to heavy groups, and these differences were statistically significant. The mean volumes of the resorption craters in the light and heavy force groups were 2 and 4 times greater than in the control groups, respectively. The mesial and distal surfaces had the greatest resorption volume, with no statistically significant difference between the 2 surfaces.

In previous studies on root resorption, resorption was quantified by making histologic cuts or by surface area measurements of resorption craters. The aims of this study were to evaluate the effects of orthodontic force magnitude on root resorption craters with volumetric measurements and also to identify the sites that might be predisposed to resorption.After an experimental time of 28 days, 36 human premolars previously divided into light-force (25 g) and heavy-force (225 g) groups were extracted and prepared for scanning electron microscope imaging. Pairs of stereo images were taken, and 3-dimensional quantitative volumetric analysis was performed with commercial software.The mean volume of the resorption crater in the light-force group was 3.49-fold greater than in the control group; the mean volume of the resorption crater in the heavy-force group was 11.59-fold greater than in the control group ( P.001). The heavy-force group had 3.31-fold greater total resorption volume than the light-force group ( P.001). Buccal cervical and lingual apical regions had significantly more resorption craters than the other regions ( P.001). There was more resorption by volume in the heavy-force group compared with the light-force group and controls. Although more resorption was recorded in the light-force group, the difference in the amount of resorption between the light-force and control groups was not statistically significant. There was significantly more resorption on the buccal cervical and lingual apical regions of the root surfaces than on the other regions, suggesting that high-pressure zones might be more susceptible to resorption after 28 days of force application.

This study examined the effect of 5 disinfection and storage protocols over different time periods on the hardness and elastic modulus of human premolar cementum. The sample consisted of 20 first premolars, which were divided into 5 groups of 4 teeth and stored in 1 of the following ways: (1) Miltons solution (1% sodium hypochlorite) for 10 minutes, (2) Miltons solution for 24 hours, (3) 70% alcohol, (4) desiccation, or (5) Milli Q (deionized water, Millipore, Bedford, Mass). Teeth in groups 1 and 2 were initially stored in Milli Q, tested within 6 hours, placed in their respective media, and retested. Groups 3, 4, and 5 were tested within 6 hours, then at 1 month, 2 months, and 3 months after extraction. Group 5 was further studied at 9 months, and 2 teeth in Group 4 were tested at 4 months. The hardness and elastic modulus of cementum was tested with the Ultra-Micro Indentation System (UMIS-2000, Commonwealth Scientific Industrial Research Organization, Australia) on unprepared specimens mounted on a 3-dimensional jig assembly. The results showed that storage in Miltons solution for 10 minutes had no significant effect on the hardness or elastic modulus, whereas storage for 24 hours caused a significant decrease in the hardness of cementum (P = .03). Storage in 70% alcohol for up to 4 months and in Milli Q for up to 9 months had no significant effects. Desiccation caused a significant increase in both the hardness and the elastic modulus from baseline to 3 months (P = .02 and P = .04, respectively), with most changes occurring within the first month. It was concluded that Miltons solution for 10 minutes could be considered an appropriate method for disinfection and removal of periodontal ligament fragments; however, its use for 24 hours should be avoided. Seventy percent alcohol and Milli Q are better storage methods, and desiccation should be avoided.

Cementum is a nonuniform connective tissue that covers the roots of human teeth. Investigation of the physical properties of cementum may help in understanding or evaluating any possible connection to root resorption. A variety of engineering tests are available to investigate these properties. However, the thickness of the cementum layer varies, and this limits the applicability of these techniques in determining the physical properties of cementum. Hardness testing with Knoop and Vickers indentations overcame some of these limitations, but they prohibited the retrieval and retesting of the sample and therefore the testing was restricted to one area or section of the tooth. Another limiting factor with the existing techniques was the risk of artifacts related to the embedding material such as acrylic. A new method to investigate the physical properties of human premolar cementum was developed to obtain a 3-dimensional map of these properties with the Ultra Micro Indentation System (UMIS-2000; Commonwealth Scientific and Industrial Research Organization, Campbell, Australia). UMIS-2000 is a nano-indentation instrument for investigation of the properties of the near-surface region of materials. Premolars were harvested from orthodontic patients requiring extractions and then mounted on a newly designed surveyor that allowed sample retrieval and 3-dimensional rotation. This novel method enabled the quantitative testing of root surface cementum, on all 4 root surfaces, extending from the apex to the cementoenamel junction at 60 different sites.

The purpose of this study was to determine whether the application of either samarium cobalt magnets or pulsed electromagnetic fields could increase the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the effect of a magnetic field on bony physiology and metabolism and to monitor for possible systemic side effects. Fifteen grams of laterally directed orthodontic force were applied to move the maxillary central incisors of a sample of 18 young male Hartley guinea pigs divided into three groups: group 1, an orthodontic coil spring was used to move the incisors; group 2, a pair of samarium-cobalt magnets provided the tooth moving force; and group 3, a coil spring was used in combination with a pulsed electromagnetic field. The results showed that both the static magnetic field produced by the samarium-cobalt magnets and the pulsed electromagnetic field used in combination with the coil spring were successful in increasing the rate of tooth movement over that produced by the coil springs alone. The mechanism producing this effect appears to have involved a reduction in the "lag" phase often seen in orthodontic tooth movement. Both magnetically stimulated groups also showed increases in both the organization and amount of new bone deposited in the area of tension between the orthodontically moved maxillary incisors.

Introduction The aim of this clinical trial was to compare the effects of 2 protocols for single-phase comprehensive treatment of Class II Division 1 malocclusion (bonded Herbst followed by fixed appliances [BH + FA] vs headgear followed by fixed appliances and Class II elastics [HG + FA]) at the pubertal growth spurt. Methods Fifty-six Class II patients were enrolled in the trial and allocated by personal choice to 2 practices, where they underwent 1 of 2 treatment protocols (28 patients were treated consecutively with BH + FA, and 28 patients were treated consecutively with HG + FA). All patients started treatment at puberty (cervical stage [CS] 3 or CS 4) and completed treatment after puberty (CS 5 or CS 6). Lateral cephalograms were taken before therapy and 6 months after the end of comprehensive therapy, with an average interval of 28 months. Longitudinal observations of a matched group of 28 subjects with untreated Class II malocclusions were compared with the 2 treated groups. Analysis of variance (ANOVA) with post-hoc tests was used for statistical comparisons. Discriminant analysis was applied to identify preferential candidates for the BH + FA protocol on the basis of profile changes (advancement of soft tissues of the chin). Results The success rate (full occlusal correction of the malocclusion after treatment) was 92.8% in both treatment groups. The BH + FA group showed a significant increase in mandibular protrusion. The increase in effective mandibular length (Co-Gn) was significantly greater in both treatment groups when compared with natural growth changes in the Class II controls. Significantly greater improvement in sagittal maxillomandibular relationships was found in the BH + FA group. Retrusion of maxillary incisors and mesial movement of mandibular molars were significant in the HG + FA group. The BH + FA group showed significantly greater forward movement of soft-tissue B-point and pogonion compared with both the HG + FA and the control groups. Two pretreatment variables were significant (F = 4.48; P Conclusions Class II treatment with either protocol during the pubertal growth spurt induces significant favorable dentoskeletal and occlusal changes. Functional jaw orthopedics had a greater favorable impact on the advancement of the chin. The clinical indications for the preferential use of the Herbst appliance at puberty are a small mandibular angle and mandibular retrusion before treatment. When treated with the BH + FA protocol, these Class II patients have the greatest probability of achieving significant improvement in the profile by advancement of the soft tissues of the chin.

Introduction The aim of this study was to measure the rate and the amount of orthodontically induced tooth movement under heavy (300 g) and light (50 g) continuous forces with superelastic nickel-titanium closing coils over a defined time (12 weeks). Methods Fourteen patients who required maxillary canine retraction into first premolar extraction sites as part of their orthodontic treatment completed this study. In a split-mouth design, precalibrated nickel-titanium closing coil springs delivering a force of 300 g or 50 g were used to distalize the canines after an alignment and stabilization period. Intraoral and maxillary cast measurements were made at the beginning of canine retraction (T0) and every 28 days for 84 days (T1, T2, T3) to assess total space closure, canine retraction rate, canine retraction and molar anchorage loss, and canine rotation. Results Statistical analysis showed that the amount of initial tooth movement (T0-T1) was not related to force magnitude; however, during the T1-T2 and T2-T3 periods, increased amounts and higher rates of tooth movement were found with heavy forces. These significantly increased the rate and the amount of canine retraction, but the adverse effects of loss of canine rotation control and anchorage were concomitantly increased. Light forces provided a greater percentage of canine retraction than heavy forces, with less strain on anchorage. Conclusions Initial tooth movement would benefit from light forces. Heavier forces tend to increase the rate and the amount of canine retraction but lose their advantage because of unwanted clinical side effects.

Introduction Root resorption can occur as a physiologic or a pathologic process, and it is an unwanted side effect of orthodontic treatment. No baseline studies have assessed this phenomenon in the absence of force variables such as mastication, parafunction, and soft-tissue pressure. In this study, we investigated the incidence and quantitative value of root resorption on unerupted third molars with normal development using microcomputed tomography. Methods Nine unerupted, nonimpacted maxillary third molars were collected from 6 patients (ages, 19.47 ± 1.89 years). The teeth were examined with microcomputed tomography and compared with teeth from other studies. (The other teeth had been treated with buccally directed light [25 g] or heavy [225 g] forces applied for 28 days, or light [25 g] or heavy [225 g] intrusion forces for 28 days.) Results Imaging and volumetric analyses showed resorption craters in many locations and with various magnitudes. Analysis of variance was completed by position (P = 0.04), surface (P = 0.07), height (P = 0.045), left or right side of the mouth (P = 0.85), and subject (P = 0.70). The midroot region on the mesial surfaces of the third molars, near the root structure of adjacent erupted second molars, had the greatest statistical significance. When compared with crater volumes of fully erupted first premolars, we found that the unerupted third molar sample had a slightly greater cube root volume per tooth than the erupted first premolars not subjected to orthodontic force and a similar cube root volume per tooth as did first premolars subjected to light (25 g) buccal and intrusive orthodontic forces. Conclusions Root resorption as a consequence of orthodontic treatment might be added to a baseline level of root resorption. The elevated results suggest that resorption might occur as part of hard-tissue remodeling and turnover, eruption, or transmission of masticatory forces through the dentition to the alveolar bone.

Elekdag-Turk, Selma/0000-0002-2799-6501; Darendeliler, Mehmet Ali/0000-0002-8906-8153 WOS: 000269522700016 PubMed: 19732664 Introduction: The reparative process of root absorption begins in the periodontium when orthodontic force is discontinued or reduced below a certain level. Our aim was to evaluate cementum repair at 4 and 8 weeks of retention after 4 weeks of continuous light and heavy orthodontic forces. The effects of age, tooth movement, and fluoride exposure were also investigated. Methods: Forty patients were recruited and divided into 4 groups of 10. The maxillary first premolars were loaded with either light (25 g) or heavy (225 g) orthodontic force. After 4 weeks of loading, the maxillary left first premolars were extracted as the positive control group, and the maxillary right first premolars were placed in retention for 4 or 8 more weeks before extraction; these were the experimental groups. The extracted teeth were studied with microcomputed tomography. To assess cementum repair, volumetric changes of the resorption craters were measured with specially designed computer software. Tooth movement was also measured on study casts taken before and after the extractions. Results: Root resorption continued for 4 weeks after orthodontic force ceased. The resorptive activity was more pronounced from heavy forces. Passive retention after 4 weeks of light force had the least root resorption crater volume (cube root scale). The total amount of the cementum repaired did not depend on magnitude of orthodontic force or retention time within our parameters (P > 0.05). This might indicate concurrence of resorption and repair during passive retention. Most repair seemed to occur after 4 weeks of passive retention following the 4 weeks of heavy forces. The volume of root resorption craters positively depended on tooth movement (P = 0.02) and negatively correlated with chronologic age (P < 0.01). Conclusions: Although there was no significant difference in the amounts of repair between groups, root resorption continued for 4 weeks after orthodontic force stopped. Resorptive activity was more pronounced after the heavy forces. The reparative processes were different between the light and heavy forces, with marked individual variations. Repair seemed to become steady after 4 weeks of passive retention following 4 weeks of light force application, whereas most repair occurred after 4 weeks of passive retention following 4 weeks of heavy force application. Root resorption crater volume positively depended on tooth movement and negatively correlated with chronologic age. (Am J Orthod Dentofacial Orthop 2009;136:320.e1-320.e10) Australian Society of Orthodontics Foundation for Research and Education; the Australian Dental Research Foundation; Dentaurum Australia Supported by the Australian Society of Orthodontics Foundation for Research and Education, the Australian Dental Research Foundation, and Dentaurum Australia. The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.

There is still ambiguity about whether continuous or intermittent orthodontic forces produce more root resorption. This prospective randomized clinical trial was designed to compare root resorption with these 2 force application patterns.The sample consisted of 16 maxillary first premolars from 8 patients who required bilateral extractions as part of their orthodontic treatment. In each subject, a fixed experimental appliance was placed on the maxillary teeth on each side, allowing a buccally directed force. The force was generated by a segmental wire of beta-titanium-molybdenum alloy. The first premolar on 1 side received a buccally directed continuous force, and the contralateral premolar received intermittent force. The initial force magnitude for both sides was 225 cN. After 14 days of initial continuous force, the intermittent force application was obtained with subsequently repeated periods until the end of the eighth week of a 3-day rest period followed by a 4-day force application period. Force levels were set to 225 cN at each patient visit. After the experimental period of 8 weeks, the teeth were extracted under a strict protocol to prevent root surface damage and analyzed with a microcomputed-tomography scan system, and specially designed software was used for direct volumetric measurements.Intermittent force produced less root resorption than continuous force (P0.05). Analysis by position showed that the buccal-cervical region had significantly more root resorption than the other positions (P0.001), corresponding to a region of compression generated by tipping.The application of intermittent orthodontic forces of 225 cN for 8 weeks (14 days of force application, 3 days of rest, then 4 days of force application repeated for 6 weeks) caused less root resorption than continuous forces of 225 cN for 8 weeks. Although it might not be clinically practical, compared with continuous forces, intermittent forces might be a safer method to prevent significant root resorption. This regimen, however, could compromise the efficiency of tooth movement.