The effect of the KTP laser on smear layer and temperature change: an in vitro study.

Abstract

The purpose of this study was to evaluate the effects of potassium-titanyl-phosphate (KTP) laser irradiation on smear layer removal and temperature changes of the root surfaces. Two hundred four extracted single-root human premolars were included. The canals were instrumented and divided into two main groups: group A (smear layer examination n:119) and group B (temperature change examination n:85). Each group was divided into subgroups (n:17) according to the different five laser power settings: A1, B1: 1W-5.33J/cm2; A2, B2: 1.5W-7.52J/cm2; A3, B3: 2W-10.3J/cm2; A4, B4: 3W-15.5J/cm2, A5, B5: 4W-20.1J/cm2, A6: positive control no laser irradiation-irrigated 2mL for 2min 2.5% NaOCl+2mL distilled water and A7: negative control groups no laser irradiation irrigated 2mL for 2min 17% EDTA+2mL for 2min 2.5% NaOCl+2mL distilled water. The temperature elevations were measured with an infrared thermographic camera and smear layer examined by scanning electron microscope. According to Kruskal-Wallis and Tukey's tests, in all groups the highest smear scores were in the apical third. In all areas, there were statistically significant differences between negative control group (17% EDTA) and all other groups (p<0.05). The highest smear scores were determined in 1W KTP laser and positive control (2.5% NaOCl) groups. Statistically, in all thirds, the differences the 3W and 4W KTP laser groups between each other and all other groups were significant (p<0.05). After the end of the use of the laser, increase in temperature values in all groups were found to be below 10°C in 20s.