Micro-computed Tomographic Evaluation of Dentinal Microcracks after Preparation of Curved Root Canals with ProTaper Gold, WaveOne Gold, and ProTaper Next Instruments.

INTRODUCTION: The aim of this study was to evaluate the influence of rotary (ProTaper Next [PTN; Dentsply Maillefer, Ballaigues, Switzerland] and ProTaper Gold [PTG, Dentsply Maillefer]) and reciprocating (WaveOne Gold [WOG, Dentsply Maillefer]) systems in dentinal microcrack generation after the preparation of curved root canals using micro-computed tomographic analysis. METHODS: Twenty-four human mandibular molars with curved roots were scanned in a micro-computed tomographic device using an isotropic resolution of 6.78 µm and randomly assigned into 1 of 3 experimental groups (n = 8) according to the root canal instrumentation system used (PTN, PTG, or WOG). Then, the root canals were prepared up to PTN X2, PTG F2, and WOG Primary instruments in the PTN, PTG, and WOG groups, respectively. After canal preparation, each specimen was scanned again. Pre- and postoperative cross-sectional images of the roots (N = 35,304) were analyzed to identify the presence of dentinal microcracks. RESULTS: Overall, 26% of the images presented dentinal defects (n = 9188). Dentinal microcracks were observed in 24.6%, 26%, and 27.4% of the postinstrumentation images from the PTN, PTG, and WOG groups, respectively. However, all of these dentinal microcracks were already present in the corresponding preoperative images. No new microcracks were generated after the preparation of curved root canals of mandibular molars using the aforementioned systems. CONCLUSIONS: Root canal instrumentation with PTN, PTG, and WOG systems did not induce the formation of new dentinal microcracks.

Sodium Hypochlorite and a Preparation Containing Glycocholic Acid and Surfactants Have a Synergistic Action on Organic Tissue Dissolution In Vitro.

INTRODUCTION: The aim of this study was to evaluate porcine palatal mucosa dissolution by sodium hypochlorite (NaOCl) with or without an auxiliary dissolving agent containing glycocholic acid and a mixture of surfactants (Keratobacter [KB]; Saint Joseph DID, Valencia, Spain). METHODS: One hundred forty samples were obtained from porcine palatal mucosa and weighed using a high-precision balance. The samples were randomly divided into 4 experimental groups (n = 35) based on the test solution used: distilled water (the negative control), CanalPro NaOCl 6% (Coltene Whaledent, Altstätten, Switzerland), KB, and a 9:1 vol/vol mixture of NaOCl with KB (NaOCl + KB). After 5, 10, 15, and 20 minutes of immersion in the solutions at 27°C ± 1°C, the samples were weighted by a blinded assessor. The intergroup weight at the different time points was statistically analyzed using the analysis of variance test with the Bonferroni posttest. RESULTS: All test groups presented with tissue dissolution although complete dissolution did not occur in any sample. The largest percent in weight reduction occurred between time points (t) = 0 minutes and t = 5 minutes for the NaOCl + KB group (22.5%) followed by KB (18.5%) for the same time period. NaOCl presented with similar tissue dissolution activity during the different time points, ranging from 7.8% (t = 10 minutes-t = 15 minutes) to 6.8% (t = 15 minutes-t = 20 minutes). Significant weight differences were found among the different experimental groups after 5, 10, and 15 minutes of incubation, with the only exception being KB versus NaOCl + KB. No significant differences were found when comparing the test groups at t = 20 minutes. CONCLUSIONS: The addition of KB to NaOCl increased porcine palatal mucosa dissolution in vitro.