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The objective of this study was to verify if differences in the design of internal hex (IH) and internal conical (IC) connection implant systems influence fracture resistance under oblique compressive forces. Twenty implant-abutment assemblies were utilized: 10 with IH connections and 10 with IC connections. Maximum deformation force for IC implants (90.58 +/- 6.72 kgf) was statistically higher than that for IH implants (83.73 +/- 4.94 kgf) (P = .0182). Fracture force for the IH implants was 79.86 +/- 4.77 kgf. None of the IC implants fractured. The friction-locking mechanics and the solid design of the IC abutments provided greater resistance to deformation and fracture under oblique compressive loading when compared to the IH abutments. [ABSTRACT FROM AUTHOR]

PURPOSE: The aim of this study was to evaluate the satisfaction of patients rehabilitated with zygomatic fixtures and prosthesis with immediate loading. MATERIALS AND METHODS: The study selected patients who were rehabilitated with zygomatic implants at the clinic of the Latin American Institute for Dental Research and Education (ILAPEO. Curitiba-PR. Brasil) between 2005 and 2009. The patients were asked to answer a control-questionnaire during their follow-up visits. Data were collected regarding the level of patient satisfaction, reason for dissatisfaction, number of post-operative clinical sessions, and the type of complication. Sixteen patients were selected: 10 females and 6 males. RESULTS: Half of the patients were completely satisfied while the other half were satisfied with some complaints. The complaints were related to hygiene, esthetics, phonetics, and discomfort during chewing. Regarding the post-operative evaluation, 50% of the patients were attended due to the prosthesis (62.5%) and the implant (37.5%). CONCLUSIONS: The treatment with zygomatic fixtures is predictable and reliable. The patients were satisfied both with implants and prosthesis. [ABSTRACT FROM AUTHOR]

Objectives: This study evaluates the clinical performance of implants with hydrophilic surface and two different macrostructures: cylindrical with perforating triangular threads (CT) and cylindrical-tapered with the association of square and condensing and perforating triangular threads (TST)., Materials and Methods: This was a multicenter split-mouth, simple-blinded, randomized, and controlled trial. Thirty patients with edentulous mandible received two CT and two TST implants. Primary stability was determined by insertion torque and resonance frequency analysis (RFA). Implants were loaded with full fixed-arch prostheses within 24 h after insertion. Clinical parameters (visible plaque index, marginal bleeding index; bleeding on probing; probing depth; and clinical attachment level) and the RFA were assessed at 2, 6, 12, and 24 months after implant loading. Marginal bone level changes were measured by comparison of standardized radiographs taken on the day of implant placement and 6, 12, and 24 months thereafter., Results: Twenty-eight patients completed the 2-year follow-up. The survival rates were 99.16% for CT implants and 100% for TST implants. One CT implant was lost until the 2 months follow-up. No significant differences were found between the two implant types for marginal bone level changes (CT 0.34 [0.24; 0.55 mm]; 0.33 [0.18; 0.55 mm]; 0.41 [0.12; 0.7 mm] vs TST 0.36 [0.14; 0.74 mm]; 0.33 [0.23; 0.63 mm]; 0.30 [0.20; 0.64 mm] at 6, 12, and 24 months, respectively) and other clinical parameters., Conclusion: The macrostructure of the implants had no influence on survival rate, primary and secondary stability, marginal bone level changes, and peri-implant clinical parameters outcomes. Both implants can be predictably used for immediate loading of full-arch mandibular prostheses., (© 2025 Wiley Periodicals LLC.)

Purpose: The aim of this study was to evaluate maxillary full-arch implant-supported fixed rehabilitations by identifying biologic complications, implant survival and success rates, and patient satisfaction with treatment. In addition, the study verified the influence of attendance at maintenance appointments on the occurrence of complications., Materials and Methods: Data were collected from clinical follow-up appointments., Results: The sample consisted of 52 patients (363 implants) with follow-up of 1 to 12 years (mean: 4.69). The main biologic complication was soft tissue recession (20.8%) at the implant level. Tissue hyperplasia was observed in eight patients (15.4%), and 17 (4.7%) implants had bone loss ≥ 2 mm. The peri-implantitis rate was 3.1% (11 implants). Implant survival and success rates were 97.8% and 93.4%, respectively. Rates of patient satisfaction with treatment were as follows: 21 (40.4%) completely satisfied, 28 (53.8%) satisfied with some complaint, and 3 (5.8%) expected more from treatment. The main complaint was the difficulty of cleaning (64.5%). Patients who attended annual follow-up appointments were associated with less bone remodeling and peri-implant disease, but no significant difference was found in biofilm accumulation., Conclusion: This type of rehabilitation is susceptible to biologic complications, but high survival and success rates and patient satisfaction were found. Periodic maintenance was associated with reduced complications, such as bone loss or peri-implantitis.

Objectives: This randomized clinical trial analyzed the long-term (5-year) crestal bone changes and soft tissue dimensions surrounding implants with an internal tapered connection placed in the anterior mandibular region at different depths (equi- and subcrestal)., Materials and Methods: Eleven edentulous patients were randomly divided in a split-mouth design: 28 equicrestal implants (G1) and 27 subcrestal (1-3 mm) implants (G2). Five implants were placed per patient. All implants were immediately loaded. Standardized intraoral radiographs were used to evaluate crestal bone (CB) changes. Patients were assessed immediately, 4, 8, and 60 months after implant placement. The correlation between vertical mucosal thickness (VMT) and soft tissue recession was analyzed. Sub-group analysis was also performed to evaluate the correlation between VMT and CB loss. Rank-based ANOVA was used for comparison between groups (α = .05)., Results: Fifty-five implants (G1 = 28 and G2 = 27) were assessed. Implant and prosthetic survival rate were 100%. Subcrestal positioning resulted in less CB loss (-0.80 mm) when compared to equicrestal position (-0.99 mm), although the difference was not statistically significant (p > .05). Significant CB loss was found within the G1 and G2 groups at two different measurement times (T4 and T60) (p < .05). Implant placement depths and VMT had no effect on soft tissue recession (p > .05)., Conclusions: There was no statistically significant difference in CB changes between subcrestal and equicrestal implant positioning; however, subcrestal position resulted in higher bone levels. Neither mucosal recession nor vertical mucosa thickness was influenced by different implant placement depths., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: This retrospective chart review study assessed patient records to determine implant insertion torque (IT) and implant stability quotient (ISQ) values during implant placement to evaluate the correlation with cortical bone anchorage (mono- or bicortical)., Methods: Primary stability data (IT during implant placement surgery and ISQ values immediately after implant placement) and cone beam computed tomography of 33 patients (165 implants) were assessed. Patients were divided into the following groups: G1, implants with apical cortical bone contact; G2, implants with bicortical bone contact (apical and cervical regions); and G3, implants with cervical cortical bone contact., Results: Sixty-eight implants were excluded due to cortical bone contact on regions other than implant apical or cervical. Ninety-seven implants were therefore assessed for this study. No implant failure was found after a mean 70.42-month follow-up time. Implants with bicortical anchorage (G2) showed higher IT (64.1 Ncm) during implant placement and higher ISQ values (76) (p < 0.05). Monocortical implants (G1, apical, and G3, cervical) showed similar IT (G1 52.3 and G3 54.3) and ISQ values (G1 71.9 and G3 73) (p > 0.05). No correlation (Pearson correlation coefficient) was found between the two stability measurement devices for the different cortical bone anchorages that were analyzed (G1 0.190, G2 0.039, and G3 - 0.027) (p > 0.05)., Conclusions: Insertion torque values and implant stability quotients were influenced by cortical bone contact. No significant correlation was found between IT and ISQ values-higher insertion torque values do not necessarily lead to higher implant stability quotients.

Statement of Problem: Mandibular fixed complete-arch dental prostheses on dental implants have been benefiting patients for a long time, but problems with passive fitting between the metallic framework of the prostheses and the implants might influence its long-term success., Purpose: The purpose of this cross-sectional study of immediately loaded mandibular fixed complete-arch dental prostheses was to evaluate the survival and success rates of prostheses, the survival rates of dental implants, the occurrence of complications in the prostheses and implants, participant satisfaction, and the association between cantilever length and prosthesis complications., Material and Methods: Data were collected from the participants' records. The exposure variables were participant related (sex and age) and treatment related (number of implants and length of cantilever). The outcome variables were the survival and success of the prostheses and implants, complications, and participant satisfaction. The Fisher or chi-square tests was used for the association between 2 qualitative variables (α=.05)., Results: Two hundred ninety consecutive participants (1429 implants) with a mean follow-up time of 4.4 years were included. The survival rate for the prostheses was 98.6 and the success rate was 96.6%. The implant survival rate was 99.6%. Sixty-seven participants experienced a prosthetic complication, the most common being tooth fracture. Only 2.45% (n=35) of the implants were associated with screw loosening. Of the total number of participants, 86.9% were completely satisfied with their treatment. The length of the cantilever (up to 25 mm) was not associated with complications (P>.05)., Conclusions: Implant-supported mandibular fixed complete-arch dental prostheses fabricated with a passive fit technique provide successful treatment for patients with edentulism. The success and survival rates of implants and prostheses were high. Only straightforward complications were observed. Cantilever length was not associated with complications., (Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Purpose: A diagnostic wax try-in has been recommended to correctly design the future prosthesis for edentulous maxillae and to predict its effect on the supporting oral tissues. The objectives of this study were to analyze (1) the reliability of this diagnostic tool in planning fixed implant-supported prostheses and (2) the amount of prosthetic compensation required., Materials and Methods: Nine female patients participated in this prospective study (mean age, 53.6 years). After anamnesis, clinical examination, and preoperative analysis, the patients underwent preoperative prosthetic preparation, and the wax try-in was fabricated. To evaluate the efficiency of the diagnostic wax try-in, three profile cephalograms were taken of each patient: (1) with the initial conventional prosthesis, (2) with the wax try-in, and (3) with the implant-supported prosthesis. Two analyses were carried out for the assessment of lip support: the nasolabial angle and Steiner's S-line. To analyze the amount of prosthetic compensation, two measurements-vertical and horizontal distances- were obtained for each wax try-in and final prosthesis., Results: For the Steiner's S-line, the results of the statistical tests indicated no significant difference between the initial and final prosthesis for the upper (P = .237) and lower lips (P = .237), and between the wax try-in and final prosthesis for the upper (P = .463) and lower lips (P = .463). Regarding the nasolabial angle, the results of the statistical tests indicated no significant difference between the initial and final prosthesis (P = .594), and between the wax try-in and final prosthesis (P = .800). Regarding prosthetic compensation, the results of the statistical test indicated no significant difference between the vertical (P = .753) and horizontal evaluations (P = .855) carried out for the wax try-in and those for the final prosthesis., Conclusion: On the basis of the data collected, it was concluded that the methods of replacing muco-supported prostheses with implant-supported fixed prostheses were efficient at maintaining the original lip design. The wax try-in was capable of predicting the future lip design and the prosthetic compensation of the final prosthesis. More studies are required to consolidate these data.

The rehabilitation of maxillary and mandibular bone atrophy represents one of the main challenges of modern oral implantology because it requires a variety of procedures, which not only differ technically, but also differ in their results. In the face of limitations such as deficiencies in the height and thickness of the alveolar structure, prosthetic rehabilitation has sought to avoid large bone reconstruction through bone grafting; this clinical behavior has become a treatment system based on evidence from clinical scientific research. In the treatment of atrophic maxilla, the use of zygomatic implants has been safely applied as a result of extreme technical rigor and mastery of this surgical skill. For cases of posterior mandibular atrophy, short implants with a large diameter and a combination of short and long implants have been recommended to improve biomechanical resistance. These surgical alternatives have demonstrated a success rate similar to that of oral rehabilitation with the placing of conventional implants, allowing the adoption of immediate loading protocol, a decrease in morbidity, simplification and speed of the treatment, and cost reduction. This case report presents complete oral rehabilitation in a patient with bilateral bone atrophy in the posterior regions of the maxilla and mandible with the goal of developing and increasing posterior occlusal stability during immediate loading.

Objectives: This randomized controlled trial used resonance frequency analysis (RFA) to assess the effects of the presence or absence of a cast rigid bar splinting multiple implants in the stability of immediately loaded implants., Material and Methods: Twenty-nine edentulous patients were randomly divided into two groups: G1 with full-arch implant-fixed prostheses and G2 with multiple implant splinting via acrylic resin denture bases. All implants were immediately loaded. RFA measurements assessed implant stability at three different times (T0--at baseline, T1--4 months, and T2--8 months. Wilcoxon and Friedman tests and a multivariate model with repeated measures for longitudinal data were used for statistical comparison (α = 0.05)., Results: Twenty-nine patients were assessed (G1 = 15 and G2 = 14). Implant and prostheses survival rates were 100% for both groups after the 8-month observation period and no significant differences in the mean ISQ values were found at the different implant stability assessment times (P > 0.05)., Conclusions: The different splinting protocols did not appear to affect implant stability during the 8-month observation period., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Purpose: To present clinical data from a 7-year follow-up study of edentulous mandibles rehabilitated according to an immediate loading protocol with prefabricated bars., Materials and Methods: Forty-four implants were inserted in 11 patients and were evaluated by means of resonance frequency analysis (RFA) and clinical and radiographic examination., Results: Ten patients returned for the 7-year evaluation and presented no implant loss. The stability measurements were performed immediately after implant placement (T0 = 64.5 ± 6.6 ISQ) and 1 year (T1 = mean 66.8 ± 4.2 ISQ), and 7 years (T7 = mean 62.8 ± 5.4) after being in function. The analysis of the RFA values showed a statistically significant decrease in implant stability after 7 years in function, although the final values are considered adequate for treatment success. Panoramic x-ray examination showed bone loss greater than the first thread in 10 implants., Conclusion: According to the obtained data, it can be concluded that immediate loading according to this protocol with prefabricated bars is a valid treatment option for edentulous patients providing sufficient long-term success.

Cemented crowns are increasingly being used on dental implants instead of on screw-retained prostheses because of the reliability of internal Morse taper implant-abutment connections. However, there is a lack of information on the fit of metal ceramic and premachined alumina infrastructures. Therefore, the aim of this study was to evaluate the marginal and internal fits of different metal and alumina infrastructures cemented on universal post abutments. A total of 45 abutments (6 mm in height and 3.3 mm in diameter) were divided into five groups on the basis of their infrastructure material: cobalt-chromium (CoCr), nickel-chromium (NiCr), nickel-chromium-molybdenum-titanium (NiCrMoTi), gold (Au), and premachined alumina. The alumina group showed marginal overextension, and the Au group showed the highest discrepancy in marginal fit among the metal alloys. The CoCr and alumina groups showed the lowest discrepancies in internal fit. In conclusion, the alumina cylinders exhibited the best internal fit, despite their horizontal overextension. Among the metal alloys, CoCr exhibited the best fit at critical regions, such as the cervical and occlusal areas., (© 2015 Eur J Oral Sci.)

The aim of this study was to measure changes in buccal alveolar crestal bone levels after immediate placement and loading of dental implants with Morse taper prosthetic abutments after tooth extraction. This study followed the STROBE guidelines regarding prospective cohort studies. The sample comprised 12 patients with a mean age of 45 years, in whom a central or upper lateral incisor was indicated for extraction. Prior to extraction, computed tomography (CT) analysis was carried out to assess the presence of the buccal bone crest. CT scans were performed at 24 h and at 6 months after immediate implant placement and immediate loading. The distance from the most apical point of the implant platform to the buccal bone crest was assessed at the two time points. The buccal bone crest height was evaluated at three points in the mesio-distal direction: (1) the centre point of the alveolus, (2) 1mm mesial to the centre point, and (3) 1 mm distal to the centre point. The values obtained were subjected to statistical analysis, comparing the distances from the bone crest to the implant platform for the two time points. After 6 months there was a statistically significant, non-uniform reduction in height at the level of the crest of the buccal bone in the cervical direction. It is concluded that the buccal bone crest of the immediate implants that replaced the maxillary incisors underwent apical resorption when subjected to immediate loading., (Copyright © 2014 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.)

Purpose: To evaluate bone response in the posterior area of edentulous mandibles rehabilitated with fixed prosthesis supported on dental implants considering baseline severity of mandibular atrophy., Material and Methods: The sample included 15 patients in whom 5 implants were inserted between the mental foramens. The prosthesis followed a cantilever extension from 15 to 20 mm. They were divided into 2 groups (severe and moderate) according to the degree of the atrophy presented. Panoramic x-ray and computerized tomography were obtained immediately after rehabilitation (T0) and after 8 months (T8). Linear measurements of the alveolar bone height at the posterior area of the mandible, 5, 10, and 15 mm from the long axis of the most distal implants, were recorded. Density measurements were also achieved at the same sites., Results: A slight bone increase in both groups was observed but with no statistically significant difference according to the baseline degree of atrophy., Conclusions: There was slight qualitative and quantitative bone improvement in the posterior area of the mandibles with the use of immediately loaded implant-supported fixed prostheses during the observed period. These results suggest that long-term follow-up is very important to understand bone behavior after rehabilitation.

Purpose: This study compared the vertical microgaps of milled zirconia and cobalt-chromium (Co-Cr) implant-supported fixed dental prosthesis frameworks to those seen in one-piece frameworks cast with different techniques., Materials and Methods: Two threaded implants were used to simulate the rehabilitation of a maxillary partially edentulous space from the second premolar to the second molar. Three-unit screw-retained prosthetic frameworks were fabricated and divided into the following groups (n = 10 in each group): 1 = cast in Co-Cr using burnout cylinders; 2 = cast in Co-Cr using cast-on Co-Cr cylinders; 3 = one-piece cast in Co-Cr using a passive fitting technique; 4 = milled Co-Cr framework; 5 = milled zirconia framework. The microgap was measured under an optical microscope at ×25. Readings were made with one screw tightened and with both screws tightened. Data were submitted to statistical analysis to enable comparison between groups (α = .05)., Results: All frameworks presented microgaps less than 70 μm under all reading conditions, except for group 1 with the readings made on the side opposite the tightened side (124.22 μm). With one screw tightened, the microgap on the tightened side was significantly smaller in groups 2, 3, and 4. On the opposite side, groups 3, 4, and 5 presented significantly smaller microgaps compared to the other groups. When both screws were tightened, the microgap was significantly smaller in groups 2, 3, and 4., Conclusion: One-piece cast frameworks associated with a passive fitting technique and milled Co-Cr frameworks presented smaller microgaps than the other fabrication methods and materials that were tested.

This study aimed to compare the index of satisfaction and masticatory function of edentulous patients before and after rehabilitation and to evaluate if patients' perception of the changes in their oral health status is in agreement with the results of masticatory performance test. Fourteen edentulous patients were rehabilitated with lower implant-supported fixed prosthesis and upper removable dentures. Index of satisfaction and masticatory capacity (subjective analysis) and performance test (objective analysis) were evaluated before and 20 days and 8 months after rehabilitation. The patients were asked to respond a yes/no masticatory capacity questionnaire and to rate their oral satisfaction on a 0 to 10 Visual Analogue Scale (VAS). Masticatory performance test comprised the ability of the individual to pulverize an artificial test food (Optocal), after 20 and 40 masticatory strokes. When baseline answers were compared to answers 8 months after treatment, all questions, excepting the ones that considered pain and social disability, were statistically different. Wilcoxon test was used to compare index of satisfaction before and after treatment. All answers showed statistically significant differences, excluding the one that referred to ease of cleaning the prostheses. Considering the masticatory performance test, Student t test (normally distributed) and Wilcoxon test (non-normally distributed) were used to test the null hypothesis that the weight of the particles of the test food left in sieves were equal in all times of evaluation. In the larger sieve with 20 cycles, statistically significant differences were observed between baseline and 8 months, 20 days and 8 months. With 40 strokes, baseline and 20 days, baseline and 8 months and 20 days and 8 months showed significant differences. It was concluded that oral rehabilitation leads to better masticatory function in edentulous patients and there is a coincidence between patient perception and real improvement on masticatory function.

The prosthetic management of a poor implant treatment is presented in this case report. The recommended occlusion concepts for implant-supported prostheses were applied for the resolution of the case. The rehabilitation of the posterior segments provided a mutually protected occlusion with adequate distribution of the axial and lateral bite forces with stable posterior occlusion. The clinical exam indicated the need for modification in the vertical dimension of occlusion. Sufficient interocclusal rest space was present to test the alteration in the vertical dimension. The aim was to achieve an occlusion scheme that followed four specific criteria: (1) centric contacts and centric relation of the jaw-to-jaw position; (2) anterior guidance only; (3) shallow anterior angle of tooth contact; and (4) vertical dimension of occlusion with acceptable tooth form and guidance. The success of an oral rehabilitation relies in following the aforementioned criteria, appropriate interaction between the dental laboratory technician and the clinician, careful elaboration of the provisional rehabilitation with all the desired details to be reproduced in the final prosthetic restoration and sufficient follow-up time of the provisional prostheses before placing the final restoration.

Purpose: The aim of this study was to compare, in vitro, external-hexagon and Morse taper implant systems with respect to bacterial sealing between implants and abutments using a new methodology., Materials and Methods: Two groups of implants were tested. Group 1 implants had an external-hexagon implant-abutment interface (Neodent) and group 2 implants featured a Morse taper (Neodent) interface. The implants were perforated apically with a 1-mm bur until the bur reached the internal chamber. Prosthetic components were adapted with the recommended torque (32 and 10 Ncm, respectively) for each group. The implants were attached to an assay vial, with the abutment end positioned into the tube. With a sterilized syringe, the assay vials were filled with liquid culture medium (brain heart infusion broth). All the specimens were sterilized by gamma radiation. After the efficacy of sterilization had been confirmed using control samples, the apical hole was carefully opened and inoculated with Escherichia coli., Results: Samples were examined daily for evidence of contamination. Within a 14-day period, 60% of the samples of group 1 were contaminated and 30% of group 2 samples were contaminated. After this period there was no further contamination in either group., Conclusion: Although both systems exhibited bacterial contamination, the Morse taper implants of the system used in this study provided a better bacterial seal than external-hexagon implants of the same system.

The purpose of this study was to warn the dental community about a possible problem in function with partial implant-supported prostheses used for long periods. The misalignment between natural teeth and the implant-supported prosthesis on teeth 11 and 12, observed in a 14-year clinical follow-up, illustrates the fact. The metal-ceramic crowns were placed in 1995 after a rigorous occlusal adjustment. Evaluations were made at 4, 6, 9, and 14 years, when it was noticed that the restorations were positioned palatally and extruded in comparison with the natural teeth. After 9 years, a greater discrepancy was noticed, with anterior occlusion and esthetic changes. The possible causes have been discussed: occlusal problems, parafunctional habits, and natural movement. The first 2 options were discarded after clinical analysis and diagnosis. Therefore, the natural movement probably deriving from an interaction of mechanical and genetic factors might have been the cause. The implants do not have periodontal ligaments but rather ankylosis, so they do not suffer those movements. This case emphasizes the need to inform patients that implants can last more than 10 years in function, but this is not the case with restorations, which lose function and esthetics and must be replaced.

Purpose: The aim of this retrospective study was to evaluate the long-term survival rates and the frequency of complications associated with single implants and their associated restorations., Materials and Methods: A retrospective cohort study was performed in patients who received dental implants between 1997 and 2007. The cohort included patients who had a single implant restored with a cemented or screwed restoration that had been in function for more than 2 years. The cumulative implant survival rates and peri-implant conditions (marginal bone loss, pocket depth, and plaque, gingival, and bleeding indices), as well as prosthodontic maintenance requirements, were evaluated. Descriptive statistics, the chi-square test, and regression models were used., Results: Seventy-three implants were placed in 44 patients (32 women, 12 men; mean age, 48 years). All implants were available for follow-up after 2 to 13 years (mean follow-up, 60 months). The overall cumulative 5-year survival rates for implants were 95.9%, and most of the prostheses (98.6%) remained functional throughout the observation period. The overall frequency of complications was 29.6% (4.3% inflammatory, 22.5% prosthetic, 2.8% operative). The average peri-implant marginal bone loss was 1.8 mm. Peri-implant soft tissue conditions such as plaque and bleeding indices and pocket depths were also satisfactory. However, the presence of inflammation was significantly associated with pocket depth and gingival keratinized mucosa. The need to retighten loose abutment screws (21%) was the most frequent prosthodontic maintenance performed. However, all loose abutment screws occurred in prostheses retained with titanium screws, and 92.9% of the prostheses had a UCLA-type abutment., Conclusion: The implants and the associated prosthetic constructions used in this study showed excellent survival rates. However, there was a high frequency of prosthetic complications associated with titanium screws and UCLA cast abutments. Other prosthetic components may have yielded different results.

Purpose: The aim of this study was to evaluate by means of digital radiography the behavior of the alveolar bone crest in external hexagon implants following the use of 2 different types of abutments, one for conventional cemented prosthesis and one for modified cemented prosthesis., Methods: Ten external hexagon implants (platform 4.1) were placed in 5 patients. Initial instrumentation was carried out to obtain primary stability of the temporary prostheses under immediate loading. Each patient received both abutments for conventional and modified cemented prosthesis. Standardized digital periapical radiographies were performed at times T0 (immediately after implant placement) and T1 (4 months after implant placement). A straight line was initially established from the implant platform to the distal and mesial peri-implantar marginal bone tissue (immediately in contact with the implant) and measured by digital radiography, using Sidexis version 2.3 (Sirona Dental Systems GmbH, Bensheim, Germany) software. The data were submitted to paired-samples t-test analysis., Results: There was no significant difference between the conventional and modified cemented prosthesis. In both cases, t-test results were within the null hypothesis level., Conclusion: The abutment for the modified cemented prosthesis resulted in no significant radiographic difference of alveolar bone crest height, when compared with the conventional cemented prostheses.

Purpose: The aim of this cohort study was to evaluate the success of implants after immediate loading in cases when the prostheses were removed for suture removal on the tenth day following implant placement. We describe a technique for fabricating effective definitive prostheses passively fitted to facilitate immediate load in edentulous patients., Materials and Methods: Seventy-one patients with resin-metal prostheses installed within less than 48 hours after implant placement were recalled. Patients for whom various amounts of time had elapsed since implant placement returned for follow-up. Time elapsed ranged from 6 months to 7 years. Stability of the implants was tested after prosthesis removal by horizontal and vertical percussion tests. Implant success was determined as the number of functional implants displaying no mobility., Results: Follow-up revealed that all implants from each period evaluated were stable, with no mobility (100% of implants success), except for the 1-year time point (99.5%) and the 2-year time point (98.9%). No signs of inflammation and/or bleeding were observed., Conclusion: Prosthesis removal for suture removal on the tenth day after implant placement represents a reliable and predictable procedure that did not jeopardize implant stability during bone remodeling.

Purpose: The objective of this study was to evaluate the stress on the cortical bone around single body dental implants supporting mandibular complete fixed denture with rigid (Neopronto System-Neodent) or semirigid splinting system (Barra Distal System-Neodent)., Methods and Materials: Stress levels on several system components were analyzed through finite element analysis. Focusing on stress concentration at cortical bone around single body dental implants supporting mandibular complete fixed dentures with rigid (Neopronto System-Neodent) or semirigid splinting system (Barra Distal System-Neodent), after axial and oblique occlusal loading simulation, applied in the last cantilever element., Results: The results showed that semirigid implant splinting generated lower von Mises stress in the cortical bone under axial loading. Rigid implant splinting generated higher von Mises stress in the cortical bone under oblique loading., Conclusion: It was concluded that the use of a semirigid system for rehabilitation of edentulous mandibles by means of immediate implant-supported fixed complete denture is recommended, because it reduces stress concentration in the cortical bone. As a consequence, bone level is better preserved, and implant survival is improved. Nevertheless, for both situations the cortical bone integrity was protected, because the maximum stress level findings were lower than those pointed in the literature as being harmful. The maximum stress limit for cortical bone (167 MPa) represents the threshold between plastic and elastic state for a given material. Because any force is applied to an object, and there is no deformation, we can conclude that the elastic threshold was not surpassed, keeping its structural integrity. If the force is higher than the plastic threshold, the object will suffer permanent deformation. In cortical bone, this represents the beginning of bone resorption and/or remodeling processes, which, according to our simulated loading, would not occur.

Objective: The purpose of this study was to evaluate the retention force of an O-ring attachment system in different inclinations to the ideal path of insertion, using devices to compensate angulations., Material and Methods: Two implants were inserted into an aluminum base, and ball attachments were screwed to implants. Cylinders with O-rings were placed on ball attachments and connected to the test device using positioners to compensate implant angulations (0 degrees , 7 degrees , and 14 degrees ). Plexiglass bases were used to simulate implant angulations. The base and the test device were positioned in a testing apparatus, which simulated insertion/removal of an overdenture. A total of 2900 cycles, simulating 2 years of overdenture use, were performed and 36 O-rings were tested. The force required for each cycle was recorded with computer software. Longitudinal sections of ball attachment-positioner-cylinder with O-rings of each angulation were obtained to analyze the relationship among them, and O-ring sections tested in each angulation were compared with an unused counterpart. A mixed linear model was used to analyze the data, and the comparison was performed by orthogonal contrasts (alpha=0.05)., Results: At 0 degrees , the retention force decreased significantly over time, and the retention force was significantly different in all comparisons, except from 12 to 18 months. When the implants were positioned at 7 degrees , the retention force was statistically different at 0 and 24 months. At 14 degrees , significant differences were found from 6 and 12 to 24 months., Conclusions: Within the limitations of this study, it was concluded that O-rings for implant/attachments perpendicular to the occlusal plane were adequately retentive over the first year and that the retentive capacity of O-ring was affected by implant inclinations despite the proposed positioners.

Purpose: This clinical study aimed to evaluate initial, 4-months, and 1-year stability of immediately loaded dental implants inserted according to a protocol of lower rehabilitation with prefabricated bars., Materials and Methods: The sample was composed of 11 edentulous patients. In each patient, 4 interforaminal implants were inserted. Immediately after implant installation, resonance frequency analysis (RFA) for each fixation was registered as well as after 4 months and 1 year with the prosthetic bar removed as it is a screwed system., Results: The clinical implant survival rate was 100%. The RFA showed an increase in stability after 4 months from 64.09 +/- 6.48 to 64.31 +/- 4.96 and 1 year, 67.11 +/- 4.37. The analysis of variance showed a statistically significant result (P = 0.015) among implant stability quotient values for the different periods evaluated. Tukey test results showed statistically significant differences between 1-year results and the initial periods but there was no statistically significant difference between initial and 4-month results (P > 0.05)., Conclusion: These preliminary 1-year results indicate that immediate loading of mandibular dental implants using the studied prefabricated bars protocol is a reliable treatment as it is in accordance with the results described in the literature for other similar techniques.

Statement of Problem: For implant-supported prostheses, passive fit is critical for the success of rehabilitation, especially when alternative materials are used., Purpose: The purpose of this study was to compare interfacial fit of implant-supported prostheses cast in titanium to those cast in gold alloy., Material and Methods: Five 3-unit fixed partial dentures were fabricated in gold alloy (Degudent U) as 1-piece castings, and 5 others were similarly cast in commercially pure titanium (Grade 1). The interfacial gaps between the prostheses and the abutments were evaluated with an optical microscope, before and after electroerosion. Readings were made with both screws tightened (10 N.cm torque), and with only 1 side tightened, so as to also evaluate the passive fit of the prostheses. Data were compared statistically by 2-way analysis of variance and the post hoc Tukey multiple range test (alpha=.05)., Results: Before electroerosion, the interfacial gaps for the 1-piece prostheses were significantly smaller (P<.001) in the gold alloy group when the screws were tightened (Au=12.6 +/- 3.0 microm, compared to Ti=30.1 +/- 6.4 microm). When the side opposite the tightened side was analyzed, there was no significant difference between the gold alloy and titanium groups (Au=69.2 +/- 24.9 microm and Ti=94.2 +/- 39.6 microm). The electroerosion procedure significantly (P<.001) reduced the gaps at the interfaces for both groups under all conditions. Comparison between groups after electroerosion did not present significant differences when the side opposite the tightened side was analyzed, but the gold alloy group showed better fit when the tightened side was analyzed (12.8 +/- 1.4 microm for gold alloy; 29.6 +/- 4.4 microm for titanium) and when both screws were tightened (5.4 +/- 2.3 microm for gold alloy; 16.1 +/- 5.5 microm for titanium)., Conclusions: Cast titanium prostheses, despite showing larger interfacial gaps between the prosthesis and abutment than those obtained with gold alloy, had improved fit after being subjected to electroerosion.