Influence of occlusal reduction on pain after endodontic treatment: a systematic review and meta-analysis.

The purpose of this systematic review was to analyze the influence of occlusal reduction on the postoperative pain levels after endodontic treatment (instrumentation and obturation of the root canal system). This review followed the PRISMA statement and was registered at PROSPERO (CRD42018107918). Two independent reviewers searched the Lilacs, Cochrane Library, PubMed (Medline), Web of Science, Scopus, Scielo, and ScienceDirect for articles published until April 2021. The research question was, "Does occlusal reduction decrease postoperative pain in endodontically treated teeth?". Only randomized clinical trials were included. The RevMan 5 program was used for meta-analysis, calculating the relative risk (RR) and 95% confidence interval (CI) of the dichotomous outcome (presence or absence of pain). The search strategies retrieved 4114 studies. Twelve studies were included for qualitative analysis and nine for quantitative analysis. The meta-analysis results did not reveal a significant difference in the reduction of postoperative pain levels for endodontic instrumentation at 6, 12, 24, 48 h and for endodontic obturation at 6 or 12 h after occlusal reduction. According to the GRADE tool, the analyzed outcome was classified as having a moderate level of certainty. It is concluded that occlusal reduction does not interfere with postoperative pain levels after endodontic treatment.

Influence of Temperature on the Cyclic Fatigue Resistance of Reciproc Blue Instruments.

AIM: To evaluate the cyclic fatigue resistance of Reciproc blue (RB) 40/0.06 instruments tested at room temperature (20° ± 0.5°C) and at body temperature (37° ± 0.5°C) in a simulated stainless steel canal. MATERIALS AND METHODS: Twenty-four new RB 40/0.06 instruments were randomly divided into two groups (n = 12) according to the temperature used. Dynamic fatigue testing was performed using an artificial stainless steel canal with a 60° curvature angle and a 5-mm radius of curvature. The temperature was controlled throughout the experiment with an underwater thermometer and a thermostat. The data were analyzed descriptively using the IBM SPSS 23.0 program, considering p < 0.05. RESULTS: The time to fracture of the RB instruments differed significantly between the two temperatures (1083.82 seconds at 20°C and 403.80 seconds at 37°C). No significant differences were found in fragment size. CONCLUSION: An increase in temperature reduces the cyclic fatigue resistance of RB 40/0.06 instruments. The results of the study suggest that an intracanal cooling system can be favorable to the fracture resistance of the tested instruments. CLINICAL SIGNIFICANCE: A cooling system of the root canal system is important in endodontic as it favors the cyclic fatigue resistance of Ni-Ti instruments.