Effect of Different Powers of ND: YAG Laser on Static Friction of Monocrystalline Ceramic Brackets

Abstract

Background and purpose: Ceramic brackets despite of beautiful view have a high friction coefficient. The aim of this study is to reduce the friction between the brackets and wires with different power radiation of Nd: YAG laser. Materials and Methods: In this study 40 monocrystalline brackets were divided into 8 groups of 5 in order to evaluate the friction in the two angle of zero and 10 degrees, 6 groups have been irradiated with 3 power of 5, 10 and 15 watt wave laser. 2 groups of 5 were not irradiated at angles of zero and 10 degrees as the control group. The .0.o19 x 0.025 stainless steel wire was pulled out from inside of brackets that artificial saliva was sprayed on them, using SANTAM Universal Testing Machine for measuring the friction. The SEM was used to evaluate the effect of laser on morphology of surface of brackets. Results were analyzed using ANOVA and T test. Results: The mean of friction in angle of 0 degrees in the control samples, 5, 10 and 15 watts, were respectively, 2.92 +/- 0.53, 1.02 +/- 0.55, 0.49 +/- 0.29 and 1.35 +/- 0.39 N, thatirradiated groups show a significant decrease compared to control group(p=0.000). The mean of friction at an angle of 10 degrees in the control samples, 5,10 and 15 watts, were respectively, 3.06 +/- 0.72, 3.03 +/- 0.97, 3.2 +/- 1.06 and 3.52 +/- 0.98 N, which were not significantly different(P>0.05). Friction values in any laser power at an angle of 10 degrees has significant increase compared to 0 degrees(P=0.000). These results can be adapted with SEM Pictures. Conclusion: The amount of friction at an angle of 0 degrees in the laser irradiated groups is reduced compared to the control group but the friction force is increased by increasing the angle to 10 degrees and is similar to bracket without irradiation.