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.

Factorial design fingerprint discrimination of Coffea arabica beans under elevated carbon dioxide and limited water conditions.

Coffee is one of the most important commodities, showing sensitivity to environmental variations. The main effects and their interaction for two levels of atmospheric CO2 concentrations and two water regimes of a factorial design were investigated for the metabolic profiles of Coffea arabica raw beans using UV fingerprint analysis from a mixture design. UV fingerprint results obtained from pure ethanol and binary ethanol-dichloromethane mixtures showed the largest metabolic discriminations between CO2 levels and their extracts were investigated in detail. The biosynthesis of major metabolites, chlorogenic acids, cafestol, kahweol and caffeine were altered owing to environmental conditions. Higher amounts of chlorogenic acids and kahweol were observed in beans from unirrigated plants grown with enriched CO2 and irrigated ones at the current CO2 level. Water availability and CO2 concentration interaction affects the metabolite amounts. Besides a significant CO2 atmospheric effect water availability was a limiting factor for metabolite content only at current CO2 level, suggesting the successful metabolic coping of CO2 enriched Arabic coffee beans suffering future droughts.

Reciproc and Reciproc Blue in the removal of bioceramic and resin-based sealers in retreatment procedures.

OBJECTIVES: To compare the remaining root canal filling material, dentin removal, apical transportation, and apical extrusion of debris after the retreatment of canals filled with bioceramic or resin-based sealers using the Reciproc or Reciproc Blue instruments. MATERIALS AND METHODS: Sixty mandibular molars with severely curved mesial roots were selected. The samples were initially instrumented with Reciproc (R25) and then divided into four experimental groups according to the endodontic sealer and retreatment instrument (n = 15): BC Sealer/Reciproc (BCRC), BC Sealer/Reciproc Blue (BCRB), AH Plus/Reciproc (AHRC), and AH Plus/Reciproc Blue (AHRB). The procedure time was measured, and an Eppendorf tube was used in each root canal to store the debris extrusion. The samples were scanned by micro-CT before and after retreatment. The apical transportation, volume of dentin, and filling material were evaluated. RESULTS: There were no significant differences in the reduction of the volume of obturator material or dentin removal between groups (p > .05). There were also no differences in the amount of extruded material or apical transportation (p > .05). The retreatment time for the AHRC group was significantly lower than that for the other groups (p = .004). CONCLUSIONS: All tested instruments obtained similar efficacy in filling material removal procedures, although no system completely removed the filling material. Retreatment of canals filled with bioceramic BC Sealer may be more time consuming. CLINICAL RELEVANCE: This study reported that Reciproc and Reciproc Blue can be indicated in retreatment of severely curved root canals filled either with bioceramic or resin-based sealers.

Effects of Reciproc, ProTaper Next and WaveOne Gold on Root Canal Walls: A Stereomicroscope Analysis.

INTRODUCTION: The aim of this study was to analyse the potential occurrence of dentinal defects after root canal preparation using three engine-driven instruments. METHODS AND MATERIALS: Eighty permanent mandibular incisors were selected. Twenty teeth did not undergo preparation, and the remaining teeth were divided into three groups (n=20): Reciproc (REC), ProTaper Next (PTN) and WaveOne Gold (WOG). The samples were dyed with methylene blue, sectioned perpendicularly to the long axis in 3-, 6- and 9-mm slices and were finally observed under a stereomicroscope (under 25×). The absence/presence of dentinal defects was documented by two blind observers. The data were analysed using Pearson's chi-squared test with a confidence level of 95% (P=0.05). The time to prepare the samples was recorded, and the groups were compared using F-test (ANOVA). RESULTS: The control group did not present any defects, and the differences between the control and experimental groups were statistically significant (P<0.05). WOG, PTN and REC caused microcracks on 60%, 33.33% and 18.33% of the samples, respectively. No significant differences between the groups in the 3-mm sections (P=0.126) were observed. There were significant differences in the 6-mm (P=0.042) and 9-mm sections (P<0.001). When WOG and PTN were used to perform root canal preparation, a significant difference was found in the average time (P=0.047). CONCLUSION: All the used instruments caused dentinal defects in the root dentin. All the instruments were used to perform the preparation with a similar average time.

Occurence of dentinal defects after root canal preparation with R-phase, M-Wire and Gold Wire instruments: a micro-CT analysis.

BACKGROUND: This study aims to evaluate the frequency of dentinal defects after root canal preparation with the ProTaper NEXT, K3XF and WaveOne GOLD systems using microcomputed tomography. METHODS: Sixty permanent mandibular incisors with a single canal were selected. Inspection of the teeth was performed under a stereomicroscope (15x) to observe the presence of pre-existing cracks and fractures lines. Samples were divided into three experimental groups (n = 20): ProTaper NEXT (PTN), K3XF (K3XF) and WaveOne GOLD (WOG). Specimens were scanned through high-resolution microcomputed tomography before and after the preparation of the root canal. Subsequently, all the axial images were examined by two different methods to find possible dentinal defects. Furthermore, an analysis of each millimeter of ten apical millimeters was also performed. The absence or presence of dentinal defects was screened by 3 pre-calibrated blinded examiners. RESULTS: After analysing all 45,720 slices, dentinal defects were observed in 48,33% (22096 slices). PTN, K3XF and WOG groups represented 11,11% (5079 slices), 17,22% (7873 slices) and 20% (n = 9144) of the cross-sectional images, respectively. At 10 apical millimeters (600 slices), 33,33% (200 slices) presented some dentinal defects, representing 7,22% (43 slices), 13,33% (80 slices) and 12,77% (77 slices) of the cross-sectional images in the PTN, K3XF and WOG groups, respectively. All the dentinal defects presented in the postoperative images existed in the images prior to instrumentation. CONCLUSIONS: There was no correlation between the preparation of a root canal using the PTN, K3XF and WOG systems and the formation of new dentinal defects.