AIMS:The aim of this study was to assess the influence of temperature and concentration on the dynamic viscosity of sodium hypochlorite in comparison with 17% EDTA and 2% chlorhexidine gluconate.SETTINGS AND DESIGN:In vitro.MATERIALS AND METHODS:Dynamic viscosity measurements of sodium hypochlorite [NaOCl (5.25%, 2.6%, 1.25%)], EDTA (17%), and chlorhexidine gluconate [CHX, 2%] were measured using a rotational digital viscometer at room temperature (25°C). The influence of temperature (45°C, 60°C) and concentration (5.25%, 2.6%, and 1.25%) on the dynamic viscosity of NaOCl was also evaluated. The measurements were performed using a circulating water bath calibrated with a thermostat, and the dynamic viscosity measurements were noted in Centipoise (Cps).STATISTICAL ANALYSIS USED:The tests used for the statistical analysis were Kolmogorov-Smirnov and Shapiro Wilk tests, one-way ANOVA, and independent sample t-test.RESULTS:Viscosity statistically increased with NaOCl concentration and decreased with increasing temperature. Amongst the tested NaOCl groups, 5.25% NaOCl at room temperature was significantly the most viscous (μ =1.5300 Cps) while 1.25% NaOCl at 60°C was significantly the least viscous (μ =1.1800 Cps).CONCLUSIONS:5.25% NaOCl and 17% EDTA are significantly viscous at room temperature. Elevating the temperature of 1.25% NaOCl to 60°C significantly reduces the viscosity of the NaOCl.

BACKGROUND:Irrigation protocol is the most critical step during the disinfection of an infected root canal system.AIM:The purpose of this study was to determine the root canal irrigation trends being practiced among the endodontic teaching faculty and post-graduate students in the dental colleges present in India.MATERIALS AND METHODS:A postal invitation to participate in this national survey was sent to the Department of Conservative Dentistry and Endodontic of 294 Dental Colleges present in India. A total of 2389 forms were successfully delivered out of which 794 duly filled forms were received back. Survey participants were asked about their irrigant selection, irrigant concentration, smear layer removal protocol, and use of adjuncts during irrigation.RESULTS:This survey elicited a positive response rate of 33.23%. Our data indicated that 92.8% of respondents use sodium hypochlorite (NaOCl) as the primary endodontic irrigant, with 26 gauge needle being most preferred for syringe irrigation, with 49.3% of them using it at a concentration of 2.6-4.0%. 68% of our respondents aim to remove the smear layer during the endodontic treatment while 47% reported using ultrasonic activation as an adjunct during their irrigation protocol.CONCLUSIONS:The findings of this survey are that the majority of teaching institutions in India are employing NaOCl (2.6-4.0%) as the primary endodontic irrigant. The concept of smear layer removal is high (68%), and there is a general trend (78%) to modify the irrigation protocol according to the status of the pulp, status of the periapex and in retreatment cases.

The purpose of this study was to study the effect of XeCl excimer laser on smear layer covered dentine of extracted human teeth. Twenty-four freshly extracted human molar teeth were collected and randomly divided into one control group and three experimental groups of six teeth each (groups A-D). The teeth in the experimental groups were irradiated with XeCl 308-nm excimer laser at a fluence of 0.4 J cm(-2) and a constant pulse repetition rate of 25 Hz. Group A was used as the control, while groups B, C and D were irradiated at different exposure times of 3, 5 and 7 s, respectively. Subsequently these teeth specimens were subjected to scanning electron microscopic (SEM) examination and energy dispersive X-ray (EDX) spectrometric analysis. The SEM examination revealed melting of the smear layer covered dentin to conceal the underlying dentinal tubules. At a longer exposure time (7 s), dentin melted to form large grains and this resulted in non-uniform closure of underlying dentinal tubules. Under the conditions of this study, it is concluded that the pulsed XeCl 308-nm excimer laser at a fluence of 0.4 J cm(-2), with an exposure time of 5 s uniformly occluded exposed smear layer covered dentine with no conspicuous variation in chemical structure.