An Esthetic Evaluation of Different Abutment Materials in the Anterior Maxilla: A Randomized Controlled Clinical Trial Using a Crossover Design.

PURPOSE: To assess the effect of implant abutment material and soft tissue thickness on the peri-implant soft tissue color using spectrophotometry and to evaluate gingival esthetics and patient satisfaction with three different abutments. MATERIALS AND METHODS: Twenty-five patients with a missing maxillary tooth in the esthetic area received an endosseous implant using a two-stage protocol. Gray titanium, pink anodized titanium, and hybrid zirconia custom abutments were fabricated for each participant and inserted for one week with a cross-over design in a randomized manner. Color measurements were made using a spectrophotometer comparing midfacial peri-implant soft tissue and marginal gingiva of the contralateral tooth. CIE Lab color scale was used following the formula: ΔE = [(∆L)2 + (∆a)2 + (∆b)2 ]½ . PES scores were recorded, and patient satisfaction questionnaires were completed at each abutment change visit and at 1-year follow-up. Statistical analysis was performed using Friedman's test and the Wilcoxon signed-rank test with Bonferroni correction as well as the Mann-Whitney U test (α = 0.05). RESULTS: Abutment material type significantly affected the ΔΕ values of the peri-implant mucosa when compared to the contralateral teeth. At baseline, the highest ΔΕ means ± standard deviation (SD) values were obtained with gray titanium (11.25 ± 2.98), followed by pink anodized titanium (9.90 ± 2.51), and zirconia abutments (6.46 ± 1.43). Differences were statistically significant irrespective of soft tissue thickness. The highest PES values were obtained with zirconia abutments (10.88 ± 0.88), followed by pink anodized titanium (10.12 ± 1.13) and the lowest with gray titanium (9.68 ± 1.41). PES differences were significant only for the thin soft tissue group. Regarding patient satisfaction, VAS scores for the pink anodized and zirconia hybrid abutment groups were higher than the gray titanium group for each question. CONCLUSION: The color difference between soft tissues around teeth and implants was significant in all groups regardless of tissue thickness. The hybrid zirconia abutments resulted in the least color difference, followed by pink anodized and gray titanium. Significantly different PES values were recorded only for the thin tissue group. There was no significant difference in patient satisfaction between zirconia and pink anodized abutments at the 1-year follow up. Pink anodized abutments represent a good esthetic alternative to zirconia hybrid abutments especially in mechanically challenging situations.

Technical Complications and Prosthesis Survival Rates with Implant-Supported Fixed Complete Dental Prostheses: A Retrospective Study with 1- to 12-Year Follow-Up.

PURPOSE: To report the rate of technical complications and prosthesis survival in a cohort of edentulous patients treated with implant-supported fixed complete dental prostheses (IFCDPs) after a mean observation period of at least 1 year. MATERIALS AND METHODS: The single-visit examination included clinical and radiographic assessment, occlusal analysis, photographs and questionnaire assessing patient satisfaction in a cohort of 52 patients rehabilitated with 71 IFCDPs (supported by 457 implants). The IFCDPs were assessed for technical complications, number of implants and cantilever extension, retention type and prosthetic material type. Comparison was made between ceramic IFCDPs (Group 1) and metal-resin IFCDPs (Group 2). Kaplan-Meier survival curve analysis was carried out for assessment of prosthesis survival and was done for both Groups 1 and 2 separately. The Cox proportional hazard model was used for survival analysis, adjusting for a number of potential confounders, to evaluate the association between prosthesis survival and several risk factors such as type of opposing occlusion, nightguard use, and presence of bruxism. Responses to patient satisfaction questions were compared with Fisher's exact test. RESULTS: Out of 71 edentulous arches (52 patients) restored with IFCDPs, 6 IFCDPs had failed, yielding a cumulative prosthesis survival rate of 91.6 % after a mean observation period of 5.2 years (range: 1-12 years) after definitive prosthesis insertion. Three IFCDPs were lost due to implant failures after 5.8 to 11 years of functional loading. Additionally, 3 metal-resin IFCDPs failed due to technical complications. Minor complications were the most frequent complications observed, namely wear of the prosthetic material (9.8% annual rate) being the most common, followed by decementation of cement-retained IFCDPs (2.9%), and loss of the screw access filing material of the screw-retained IFCDPs (2.7%). The most frequently observed major complication was fracture of the prosthetic material (1.9% annual rate), followed by fracture of occlusal screw (0.3%), and fracture of framework (0.3%). The annual rate of wear of prosthetic material was 7.3% for porcelain IFCDPs (n = 19/55) and 19.4% for metal-resin IFCDPs (n = 13/16), yielding a statistically significant difference between the 2 groups (p = 0.01). CONCLUSIONS: After a mean exposure time of 5.2 years, 91.6% prosthesis survival rates were achieved (65 out of 71 IFCDPs). The most frequent minor technical complication was wear of the prosthetic material with estimated 5-year rate of 49.0%, while the most frequent major complication was fracture of the prosthetic material with estimated 5-year dental unit-based rate of 9.5%. The cumulative rates for "prosthesis free of minor complications" at 5- and 10-years were 60.5% (95% CI: 47.2-71.3%) and 8.9% (95% CI: 2.9-18.0%), respectively. The cumulative rates for "prosthesis free of major technical complications" at 5- and 10-years were 85.5% (95% CI: 73.0-92.5%) and 30.1% (95% CI: 12.0-50.6%), respectively. Presence of bruxism, and absence of a nightguard were associated with increased risk for chipping of the prosthetic material of the IFCDPs.

Double Full-Arch Fixed Implant-Supported Prostheses: Outcomes and Complications after a Mean Follow-Up of 5 Years.

PURPOSE: To retrospectively assess complications and clinical and radiographic outcomes of edentulous patients treated with double full-arch implant-supported fixed complete dental prostheses (IFCDPs) after a mean observation period of 5.1 years. MATERIALS AND METHODS: The single-visit clinical and radiographic examination included medical and dental history review and clinical assessment of biologic and technical complications encountered with all implants and IFCDPs. Life table analysis and Kaplan-Meier survival curves were calculated. Analysis was conducted to evaluate the association between prosthesis survival and several risk factors such as type of opposing occlusion, nightguard use, and presence of bruxism. RESULTS: Nineteen edentulous patients restored with 38 IFCDPs were included. A total of 249 implants were placed and 2 implants failed after a mean observation period of 5.1 years (range: 1-12 years), yielding an overall implant survival rate of 99.2% and prosthesis survival rate of 92.1%. Three out of 38 IFCDPs were lost, 1 after implant losses and 2 due to technical complications. The most frequent minor biologic complication was soft tissue recession with an estimated 5-year rate of 45.5% (95% CI: 39.4-57.5), while the most frequent major complication was peri-implantitis with an estimated 5-year implant-based rate of 9.5% (95% CI: 6.7-11.3). The most frequent minor technical complication was wear of the prosthetic material with an estimated 5-year rate of 49.0% (95% CI: 37.4-76.4), while the most frequent major technical complication was fracture of the prosthetic material with an estimated 5-year dental unit-based rate of 8.0% (95% CI: 6.6-10.1). CONCLUSIONS: After a mean use time of 5.1 years, high implant and prosthesis survival rates were observed. The most frequent major biologic complication was peri-implantitis, and the most frequent major technical complication was fracture of the prosthetic material. The 5-year estimated cumulative rates for "prosthesis free of biologic complications" was 50.7% (95% CI: 33.7-65.4) and for "prosthesis free of technical complications" was 57.1% (95% CI: 39.3-71.5).

Implant survival rates and biologic complications with implant-supported fixed complete dental prostheses: A retrospective study with up to 12-year follow-up.

OBJECTIVES: To assess the rate of biologic complications and implant survival in edentulous patients treated with implant-supported fixed complete dental prostheses (IFCDPs) after a mean observation period of 5.2 years (range: 1-12 years). MATERIALS AND METHODS: A single-visit clinical and radiographic examination was performed to assess types and rates of biologic complications with ceramic IFCDPs (Group 1) and metal-resin IFCDPs (Group 2). RESULTS: Of 457 rough surface dental implants supporting 71 IFCDPs (52 patients), six had failed, yielding an implant survival rate of 98.7% after a mean observation period of 5.2 years after definitive prosthesis insertion. The most frequent minor biologic complication was soft tissue recession (7.7% annual rate), inflammation under the IFCDP (7.4% annual rate), and peri-implant mucositis (6.3% annual rate). The most frequent major biologic complication was peri-implantitis (2.0% annual rate), in 46/457 implants (10.1%) supporting 19 IFCDPs and late implant failure (0.3% annual rate). The frequency of biologic complications was not statistically different between Group 1 and Group 2. The presence of high plaque index had significant effect on bone loss. CONCLUSIONS: After a mean exposure time of 5.2 years postdefinitive prosthesis insertion (range: 1-12 years), implant survival rate of 98.7% was achieved. The six implant failures in three patients occurred after 5 years and affected the prosthesis survival. Soft tissue recession was the most frequent minor biologic complication, whereas peri-implantitis was the most frequent major biologic complication. A 10-year implant-based mucosal recession rate of 77% (95% CI: 68.2-87.9) and a 10-year implant-based peri-implantitis rate of 20% (95% CI: 16.9-24.9) were found.

Digital Evaluation of Three Splinting Materials Used to Fabricate Verification Jigs for Full-Arch Implant Prostheses: A Comparative Study.

PURPOSE: The primary aim of this study was to assess the accuracy of different splinting materials to make implant cast verification jigs. The secondary aim was to assess the effect of 20° implant angulation on the accuracy of casts. MATERIALS AND METHODS: An edentulous mandibular arch with five internal connection tissue level implants served as control. The three implants in the anterior region were parallel to each other and the two implants in the posterior region were distally tilted 20° bilaterally. Verification jigs were fabricated with three different materials by splinting prefabricated bars to temporary abutments, resulting in three different groups (n = 15 specimens). Test casts were fabricated with low expansion type IV stone, and subsequently digitized with reference scanner. The STL files from the test casts and the control were superimposed, in order to determine the three-dimensional (3D) deviations. RESULTS: Group 1 (GC Pattern Resin) had a mean (SD) value of 36.59 (12.47) µm; Group 2 (Fixpeed Resin) had a mean (SD) value of 35.9 (10.13) µm; and Group 3 (Triad Gel) had a mean (SD) of 34.12 (7.10) µm. One-way ANOVA showed no statistically significant difference between groups (p = 0.790). For the comparative analysis of the effect of implant angulation, data were normally distributed for Groups 1 and 3 (GC Resin and Triad Gel), but not for group 2 (Fixpeed Resin). The difference between parallel and tilted implants was significant for all three groups: GC Resin (p = 0.024; paired t-test), Fixpeed Resin (p = 0.002; Wilcoxon signed-rank test), and Triad Gel (p = 0.002; paired t-test). CONCLUSIONS: There were no statistically significant differences between the 3D deviations of the test casts fabricated from verification jigs made by three materials (GC Pattern Resin, Fixpeed Resin, and Triad Gel). Parallel implants had nominally significantly less 3D deviations compared with 20° distally tilted implants, but not clinically significant. CLINICAL SIGNIFICANCE: The results of the present study indicate that more than 20° of angulation, has an effect on the 3D accuracy. However, even though the tilted implants had nominally significantly more 3D deviation, it was not clinically significant. The clinical implications of this in vitro study are relevant to the popular full-arch implant rehabilitation concept of tilted and axial implants such as the All-on-four concept. Tilting the posterior implants to increase the antero-posterior spread increases the implant angulation which is then corrected with 30° angulated abutments. This in vitro study shows that even after correction with angulated abutments if the remaining angulation is up to 20°, framework fit may still be achieved. Verification jig is essential tool to achieve the framework fit. (J Esthet Restor Dent 29:102-109, 2017).

Muscle weakness after repeated injection of botulinum toxin type A evaluated according to bite force measurement of human masseter muscle.

BACKGROUND: Botulinum toxin type A (BTX-A) has been applied successfully to treat masseteric hypertrophy, but it can cause muscle weakness. OBJECTIVE: To measure the change in maximum bite force (MBF) after BTX-A injection into the human masseter muscle and to evaluate the influence of a booster (repeated) injection. METHODS: Thirty volunteers completed 18-week follow-up, and MBF was measured. At 18 weeks after the first injection, a booster injection was given to 14 patients, and they were followed up until 18 weeks from the booster injection. RESULTS: Mean MBF was approximately 20% lower at 2 weeks than before the injection, and it recovered gradually after 4 weeks to return to the preinjection level at 12 weeks. MBF differed significantly between before the injection and at 2, 4, and 8 weeks after the injection (p<.05). In the booster injection group (n=14), MBF was markedly lower at 6 weeks (p<.05), and it recovered gradually in 12 weeks. CONCLUSION: MBF was significantly lower after booster injection of BTX-A into the human masseter muscle, but it gradually recovered in a predictable pattern, and the degree of discomfort experienced by the subjects had little effect on normal mastication.