The aims of this study were to evaluate the physical and chemical properties, cytotoxicity and dentinal tubule penetration of a new calcium silicate-based root canal dressing. For pH and calcium ion release evaluation (1, 24, 72 and 168 h) were used a pH meter and colorimetric spectrophotometer, respectively. Radiopacity evaluation followed the ISO 6876:2012. Cytotoxicity was evaluated by the percentage of cell viability using MTT assay. Illustrative images of dentinal tubule penetration were obtained using confocal laser scanning microscopy (CLSM). Data from pH and calcium ion release were statistically analyzed by two-way analysis of variance and Tukey test. Radiopacity was analyzed using the Student t-test. The statistical tests for cytotoxicity results were the one-way analysis of variance and Tukey test. Both materials showed alkaline pH in all experimental times. The pH values for calcium hydroxide paste were higher than bioceramic paste at 1, 24, and 72 h (p<0.05). The calcium ion release of bioceramic was lower than the calcium hydroxide paste only at 24 h (p<0.05). The bioceramic was more radiopaque than the calcium hydroxide paste (p<0.05). Bioceramic paste presented a dose and time-dependent cytotoxic effect after MTT assay. CLSM images showed absence of tubule penetration for both pastes. The new calcium silicate-based canal dressing presented alkaline pH, high calcium release, and acceptable radiopacity. Bio C Temp showed a dose and time-dependent cytotoxic and absence of dentinal tubule penetration.

Abstract This study aimed to evaluate penetrability on dentinal tubule of a new bioceramic sealer through confocal laser scanning microscopy (CLSM). A specific fluorophore (Fluo-3) was mixed with the sealer. Forty distobuccal roots from maxillary molars were selected, and root canal preparation was carried out with Wave One Gold # 35.06 instruments. Roots were randomly assigned to 4 groups according to the filling procedures: Bioceramic/Lentulo (Sealer Plus BC); Bioceramic/EasyClean group, three activation of the sealer (3x20 s) with Easy Clean instrument; Bioceramic/Irrisonic: ultrasonic activation for 30 s; and AHplus/Lentulo: epoxy resin based sealer (AH Plus) was utilized with the same protocol as the BC/LE group. After 72 h, specimens were transversally sectioned at 2 and 7 mm from root apex and then analyzed through CLSM. Sealer penetration area on dentinal tubule was measured by Adobe Photoshop CC2018. Kruskal Wallis and Wilcoxon T tests were carried out. Penetrability results were similar for both sealers regardless of which technique was performed to activate them inside the root canal (p>0.05). It is reasonable to conclude that penetration of bioceramic and epoxy resin based sealers occurred unimpressively. The type of instrument used to activate bioceramic sealer did not affect penetrability. Fluo 3 should be recommended as the fluorophore to evaluate dentinal tubule penetration of bioceramic sealers.

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The aim of this study was to evaluate the effect of 95% ethanol irrigation, with 5 or 10 min of action, on the antibacterial properties of 2% chlorhexidine (CHX), on oral biofilm, evaluated with confocal laser scanning microscopy (CLSM). Oral biofilm development was induced in 80 sterilized bovine dentin blocks, distributed in two groups (5 or 10 min) and 4 subgroups, according to time and the solution used: Saline (SALINE5, SALINE10); Saline followed by CHX (SALINE/CHX5, SALINE/CHX10); Ethanol (ETHANOL5, ETHANOL10), Ethanol followed by CHX (ETHANOL/CHX5, ETHANOL/CHX10). The surface of the block was dyed with Live/Dead BacLight. Images from different areas were analyzed by BioImage L program. The total biovolum (µm³), biovolum of live cells (green), percentage of live cells of the thickness of the biofilm visualized in CLSM and on surface biofilm were evaluated. Total biovolum and biovolum of living cells showed similar results among the different groups (p > .05). The percentage of living cells in total thickness of the biofilm also was similar among the groups (p > .05), except ETHANOL5, SALINE/CHX10, ETHANOL10, and ETHANOL/CHX10 that showed lower percentage than SALINE5 (p < .05). The ETHANOL10 and ETHANOL/CHX10 also showed lower percentage of living cells than ETHANOL/CHX5 and SALINE10 (p < .05). In relation to biofilm surface, SALINE/CHX5, SALINE/CHX10, ETHANOL5, ETHANOL10, ETHANOL/CHX5, and ETHANOL/CHX10 showed a lower percentage of living cells percentage than SALINE5 and SALINE10 groups (p < .05). Therefore, ethanol has no effect on antimicrobial properties of 2% chlorhexidine, prior when used as endodontic irrigating solution.

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