Wettability of root canal sealers on intraradicular dentine treated with different irrigating solutions.

OBJECTIVES: The aim of this in vitro study was to evaluate the wettability of AH Plus and ThermaSeal Plus sealers on intraradicular dentine treated with different irrigating solutions. METHODS: Fifty anterior teeth were decoronated and split longitudinally. Each root half was divided into 5 groups (n=10). Group I: 5mL of 2.5% NaOCl+QMix. Group II: 5mL of 2.5% NaOCl+17% EDTA. Group III: 5mL of 2.5% NaOCl+7% maleic acid. Group IV: 5mL of 2.5% NaOCl. Group V: 5mL of distilled water. Irrigation regimens were performed for 1min. Each specimen was placed inside a Dynamic Contact Angle Analyser. A controlled-volume droplet of sealer was placed on each specimen and the static contact angle was analysed. RESULTS: The contact angle made by both sealers with EDTA-irrigated dentine was significantly larger when compared to the other irrigants (P<0.05). For ThermaSeal Plus, contact angles produced on maleic acid-, NaOCl- and distilled water-irrigated dentine were not significantly different, but were all significantly larger than the contact angle produced on QMix-irrigated dentine (P<0.05). For AH Plus, contact angles produced on NaOCl- and distilled water-irrigated dentine were not significantly different, but were significantly larger than those made by maleic acid and QMix. CONCLUSION: When used as a final irrigant, QMix favours the wetting of root canal dentine by both AH Plus and ThermaSeal Plus sealers. Maleic acid shows a promising result when compared to EDTA and NaOCl. Wettability of both sealers is the worst on EDTA-irrigated dentine. CLINICAL SIGNIFICANCE: The present study highlights the effect of newer endodontic irrigating solutions on the wettability of sealers on to the root canal dentine, which is required for obtaining good obturation seal.

The effect of QMix, an experimental antibacterial root canal irrigant, on removal of canal wall smear layer and debris.

INTRODUCTION: This study examined the ability of two versions of QMix, an experimental antimicrobial irrigant, on removal of canal wall smear layers and debris using an open canal design. METHODS: Cleaned and shaped single-rooted human root canals were irrigated with NaOCl as the initial irrigant and one of the following as the final irrigant: (1) QMix I (pH = 8), (2) QMix II (pH = 7.5), (3) distilled water, (4) 17% EDTA, and (5) BioPure MTAD (Dentsply Tulsa Dental Specialties, Tulsa, OK). Smear and debris scores were evaluated in the coronal, middle, and apical thirds of longitudinally fractured canal spaces using scanning electron microscopy and analyzed using Cochran-Mantel-Haenszel statistic. RESULTS: Smear scores, when the overall canal was considered, differences were observed among groups except groups 1 versus 4 and groups 2 versus 4. After adjusting for canal levels, all groups differed significantly from each other (p < 0.005) with the exception of groups 2 versus 5. For the debris scores, no significant difference was observed among the treatment groups when the overall canal was considered and after adjusting for the effect of canal level. CONCLUSION: Within the limitations of an open-canal design, the two experimental QMix versions are as effective as 17% EDTA in removing canal wall smear layers after the use of 5.25% NaOCl as the initial rinse.

In vitro osteogenic potential of an experimental calcium silicate-based root canal sealer.

OBJECTIVE: This in vitro study compared the cytotoxicity and osteogenic potential of an experimental calcium silicate-based sealer with an epoxy resin-based sealer (AH Plus; Dentsply Caulk, Milford, DE) and a zinc oxide-eugenol-based sealer (Pulp Canal Sealer; SybronEndo, Orange, CA). METHODS: Disks prepared from the respective sealer and from Teflon (negative control) were placed in direct contact with a MC3T3-E1 osteogenic cell line at 6 weekly intervals after immersion in a culture medium. Succinic dehydrogenase activities were evaluated using 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Extracts from these sealers after the 6-week immersion period were investigated also by MTT assay. Aged sealers were then switched to an osteogenic medium for examination of the alkaline phosphatase activity and mineralization of extracellular matrices produced by the differentiated cells. RESULTS: All sealers exhibited severe toxicity after 24 hours, after which toxicity decreased gradually over the experimental period except for Pulp Canal Sealer, which remained severely toxic. Toxicity of the extracts derived from the sealers was concentration dependent, with those derived from the experimental sealer being the least cytotoxic at a 1:10 dilution. Minimal alkaline phosphatase activity and no bone formation were seen with Pulp Canal Sealer. The production of alkaline phosphatase was less intense for the experimental sealer at 7 days. However, both AH Plus and the experimental sealer did not inhibit mineralization of the extracellular matrix after 28 days. CONCLUSION: The experimental calcium silicate-based sealer may be regarded as minimally tissue irritating and does not interfere with bone regeneration even when it is inadvertently extruded through the apical constriction.