Undetected microscopic pulp exposures in deep class II cavities.

Exposure of the pulp may act as a great insult during preparations, so this study investigated the probability of clinically undiagnosed pulp microexposures. The axial wall of 30 deep class II preparations in human premolars was searched for any microexposure after extraction. Seven teeth (23.7 percent) showed some kind of exposure. It is concluded that approximately one-fifth of class II preparations with the remaining dental thickness (RDT) less than 0.5 mm may have a pulpal microexposure.

Undetected microscopic pulp exposures in deep class II cavities.

Exposure of the pulp may act as a great insult during preparations, so this study investigated the probability of clinically undiagnosed pulp microexposures. The axial wall of 30 deep class II preparations in human premolars were searched for any microexposure after extraction. Seven teeth (23.7 percent) showed some kind of exposure. It is concluded that approximately 1/5 of class II preparations with the RDT less than 0.5mm may have a pulpal microexposure.

Histopathology study on pulp response to glass ionomers in human teeth.

OBJECTIVE: Evaluation of the pulpal response to a resin-modified glass ionomer, a conventional glass ionomer and calcium hydroxide. METHODS AND MATERIALS: Fifty-five deep Class V cavities were lined with Vivaglass Liner, Chembond Superior and Dycal. After seven, 30, and 60 days the teeth were extracted and a histological assessment was performed. RESULTS: There was no statistically significant difference in pulpal response among the three groups for the same time interval (P > 0.05). CONCLUSION: Light-cured glass ionomers have similar advantages to conventional glass ionomers.

Effect of preflaring on working length determination: an in vivo study.

This study is designed as an in vivo study to evaluate the impression of the preflaring method on working length determination in curved canals.

The effect of 16 percent carbamide peroxide on enamel staining susceptibility.

STATEMENT OF PROBLEM: Recently, vital bleaching by carbamide peroxide has become more popular; therefore, it is necessary to study the effect of this agent on enamel and dentin. PURPOSE: The purpose of this study was to evaluate the effect of a 16 percent carbamide peroxide bleaching gel, Vivastyle, on enamel staining susceptibility. MATERIALS AND METHODS: Thirty bovine specimens were selected and randomly divided into two groups of 15. The experimental group was subjected to Vivastyle gel and then was immersed in coffee for half an hour daily for three weeks. The control group was only immersed in coffee. The teeth were evaluated using a colorimeter to measure L*, a*, b* of each tooth. Value (black to white) is denoted as L*, wheres chroma (a* b*) is denoted as red (+a*), green (_a*), yellow (+b*), and blue (_b*). Total color differences between two colors (deltaE) were calculated using the following formula: deltaE = [(deltaL*)2 + (deltaa*)2+(deltab*)2]: deltaE1.Bleached, AE2: bleached and immersed in coffee, deltaE3: immersed in coffee. RESULTS: Mean differences were: deltaE1 = 9.478, deltaE2 = 13.808 and deltaE3 = 7.230. Paired comparison by use of Duncan test showed there was a significant difference between deltaE1 and deltaE2 (P0.000); and t test showed there was no significant difference between deltaE3 and deltaE1. (P0.08 > 0.05), but deltaE3 showed a significant difference with deltaE2(P0.000). CONCLUSION: After vital bleaching, the enamel staining susceptibility significantly increased.

Evaluation of apically extruded debris in conventional and rotary instrumentation techniques.

OBJECTIVE: The purpose of this in vitro study was to compare two common techniques, conventional and rotary instrumentation, in debris extrusion. METHODS AND MATERIALS: Two hundred mature human teeth with mature apices and less than 15 degrees of root curvature as determined by Schneider's method were selected for use. Teeth were randomly divided into four groups of 50 teeth each and prepared using step-back instrumentation and profile 4 percent Taper Series 29 rotary system at three different speeds: 1,000 rpm, 8,000 rpm and 24,000 rpm. All of the speeds were reduced by contra angle to 1/6 rpm. Extruded debris were collected on pre-weighed vials containing distilled water through the apical foramen during instrumentation. The vials were then dried in a microwave oven at 150 degrees Celsius and weighed again. The difference was recorded as "the weight of the extruded debris." Eight control vials, two for each group, were weighed and filled with distilled water, dried, and reweighed. The mean weight of extruded debris for each group was statistically analyzed. T-student, unilateral variance analysis and Pearson tests were used in this study. RESULTS: Step-back instrumentation (Group 1) produced significantly more debris than other groups. The difference in the amount of debris produced among rotary groups was not significant. CONCLUSION: Rotary technique could reduce the amount of debris extrusion.

The accuracy of the Neosono Ultima EZ apex locator using files of different alloys: an in vitro study.

The purpose of this study was to compare the precision of one of the new generation of root canal measuring devices, Neosono Ultima EZ, while using files manufactured of different alloys. Fifty-four root canals of extracted teeth were chosen. They were placed in special tubes with roots immersed in 2 percent agar with phosphate buffered saline. The device was used to locate the apex of each canal in wet conditions at the zero digital reading, first using a stainless steel file and then using a nickel-titanium file. These values were compared to the actual lengths obtained by measuring the distance of the coronal reference point to the apical opening with a size 10 file minus 0.5 mm. The accuracy of the device was 94 percent with nickel-titanium files and 91 percent with stainless steel. No significant difference was noted between the results for either file. The accuracy of the Neosono Ultima EZ in wet conditions exceeded 90 percent regardless of the alloy used.