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The aim of this study was to analyze and compare the efficacy of different bleaching agents typically used for internal bleaching of endodontically treated discolored teeth. Electronic databases (PubMed, Web of Science, and Cochrane Library) were searched by 2 reviewers for clinical trials in which the color of endodontically treated discolored teeth before and after internal bleaching was examined using shade guide units (ΔSGU) or a spectrophotometer/colorimeter (ΔE). The efficacies of the bleaching agents were compared using subgroup analyses. Statistical heterogeneity was assessed with the Cochran Q test and I 2 statistic. Publication bias was evaluated using funnel plots. Eight studies were included in the systematic review, 6 of which could be included in the meta-analyses. Internal bleaching led to a significant change in tooth shade (ΔSGU: 6.27 [95% confidence interval, 5.36–7.17], ΔE: 12.83 [95% confidence interval, 9.46–16.20]). With regard to ΔSGU, the use of carbamide peroxide (35% or 37%), hydrogen peroxide (35%), and the combination of sodium perborate and hydrogen peroxide (3% or 30%) led to a better bleaching effect than sodium perborate (adjusted P value ≤.026). Regarding ΔE, there were no significant differences between carbamide peroxide (37%), hydrogen peroxide (35%), and sodium perborate mixed with hydrogen peroxide (P =.051). The risk of bias of the included studies was classified as moderate to high. Carbamide peroxide, hydrogen peroxide, and sodium perborate have a significant bleaching effect on discolored, root canal–treated teeth. For a valid assessment of shade stability and a comparison of bleaching agents and their concentrations, further studies with long-term recalls are necessary. [ABSTRACT FROM AUTHOR]

This retrospective study aimed to analyze the effect of repairing endodontic access cavities with composite on the survival of single crowns and retainer restorations of fixed or removable dental prostheses. Dental records of patients attending a university dental clinic were retrospectively screened for single crowns and retainer restorations receiving endodontic treatment after crown placement. Survival (no further intervention) and failure (removal, loss or replacement of crown, replacement of access restoration, or recementation of restoration) of crowns and retainers with repaired endodontic access cavities were recorded. The mean annual failure rates were calculated, and the effect of individual-, tooth-, and restoration-related variables on survival was assessed by univariate log-rank tests and multivariate Cox regression analyses with shared frailty (P <.05). One hundred eighty repaired crowns/retainers placed in 151 patients were included (4.5 ± 3.3 years follow-up). Survival after 2, 5, 7, and 10 years amounted to 82.7%, 71.5%, 67.3%, and 48.8% (mean annual failure rate = 9.0%, 6.5%, 5.5%, and 6.9%), respectively. Although tooth type, kind of restoration, endodontic irrigant, repair conditioning methods, and kind of composite affected survival in the univariate regression analyses, only the kind of restoration (single crown vs retainer restoration) remained significant in the multivariate Cox regression model. Repairing endodontic access cavities with composite increases the longevity of single crowns and retainer restorations. [ABSTRACT FROM AUTHOR]

The study aimed to compare the repair bond strength of aged composite and amalgam repaired with resin composite after various mechanical and adhesive surface treatments. Specimens were aged by thermal cycling (10,000 cycles, 5-55°C) and randomly subjected to one of three surface treatments: diamond bur abrasion, aluminum oxide air abrasion, or silica coating. Conventional bonding or a universal adhesive with incorporated silane was applied afterward (each n = 16) and resin composite was attached. In the control groups (each n = 16), resin composite was attached using one of the above adhesives without prior mechanical surface conditioning. After further thermal cycling, the shear bond strength (SBS) and failure modes were assessed. Statistical analyses were performed using ANOVA, Weibull statistics, two sample t-tests, and Chi2-test (P < 0.05). The SBS of the repaired amalgam was significantly lower than that of the composite and mechanical pretreatment significantly increased SBS. The universal adhesive significantly improved the SBS of the repaired amalgam compared to the conventional bonding agent and mechanical pretreatment increased the number of cohesive/mixed failures. Amalgam restorations may be repaired using resin composites, but the resulting SBS is lower than that obtained with composite. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate dental students' retention of factual and procedural knowledge gained in a preclinical course in operative dentistry during a clinical dental curriculum. In 2017, all 157 seventh- to tenth-semester dental students at a dental school in Germany were asked to repeat the same written examination performed at the end of the preclinical course in the sixth semester. The examinations consisted of 30 multiple-choice questions covering factual and procedural knowledge. The percentage of correctly answered questions per exam and differences in correct answers between the original examination and the re-examination (per question) were analyzed. Students were also asked to self-rate their percentage of correctly answered questions and their knowledge in various disciplines of operative dentistry at the times of the original examination and the re-examination. After exclusions, data were analyzed for 129 students, for a participation rate of 82%. For the seventh- and tenth-semester students, the results on the original examination and the re-examination were not significantly different, while the eighth- and ninth-semester students performed significantly better on the original examination than the re-examination. In all semesters, procedural knowledge remained stable between the original examination and the re-examination, while factual knowledge decreased slightly. Their performance on the original examination was underestimated by the eighth- and ninth-semester students. All the students underestimated their performance on the re-examination. Students mostly rated their knowledge level significantly higher on the original examination than on the re-examination. Overall, this study found that factual and procedural knowledge gained in a preclinical course in operative dentistry was not increased during the clinical dental curriculum. [ABSTRACT FROM AUTHOR]