Ashnagar Sajjad, Monzavi Abbas, Abbasi Mehdi, Aghajani Mahdi, Chiniforush Nasim
Department of Periodontics and Oral Medicine, Michigan School of Dentistry, MI, USA.
Laser Research Center of Dentistry (LRCD), Dental Research Institute, Tehran University of Medical Sciences, Tehran, Iran.
J Lasers Med Sci. 2017 Summer;8(Suppl 1):S62-S67. doi: 10.15171/jlms.2017.s12. Epub 2017 Aug 29.
Today, bleaching is a routine noninvasive alternative for treatment of discolored teeth. The aim of this study was to determine whether conventional or laser activated bleaching predispose teeth to develop caries or not. Sixty human molars were mounted on acrylic cylinders and their Knoop microhardness (KHN) as well as DIAGNOdent (DD) values were recorded. They were divided into 4 experimental groups; G1) conventional bleaching with 40% hydrogen peroxide gel, G2) Diode laser assisted bleaching with same gel, G3) Nd:YAG laser assisted bleaching with the same gel, G4) control group. After bleaching, all samples were subjected to a three day pH cycling regimen and then, KHN and DD values were measured. All groups had significant reduction in KHN values. It seems that there is no statistically meaningful difference between changes in enamel microhardness of the sample groups and all groups have changed in a similar amount. Reduction of DD scores were significant in Diode laser and conventional groups, however changes in Nd:YAG laser and control groups were not significant. Changes in DD values have followed a similar pattern among groups, except in G1- G4 and G2-G4 couples. Conventional and diode laser groups had a meaningful difference in reduction of DD values in comparison with the control group. It can be concluded that bleaching whether conventional or laser activated, does not make teeth vulnerable to develop carious lesions.
如今，牙齿美白是治疗牙齿变色的一种常规非侵入性方法。本研究的目的是确定传统美白或激光活化美白是否会使牙齿更易发生龋齿。将60颗人类磨牙安装在丙烯酸圆柱体上，并记录其努氏显微硬度（KHN）以及激光龋齿诊断仪（DD）值。它们被分为4个实验组；G1）用40%过氧化氢凝胶进行传统美白，G2）用相同凝胶进行二极管激光辅助美白，G3）用相同凝胶进行钕钇铝石榴石激光辅助美白，G4）对照组。美白后，所有样本接受为期三天的pH循环方案，然后测量KHN和DD值。所有组的KHN值均显著降低。样本组牙釉质显微硬度的变化之间似乎没有统计学上的显著差异，且所有组的变化量相似。二极管激光组和传统美白组的DD评分降低显著，然而钕钇铝石榴石激光组和对照组的变化不显著。除了G1 - G4组和G2 - G4组对之外，各组之间DD值的变化遵循相似模式。与对照组相比，传统美白组和二极管激光组在DD值降低方面存在显著差异。可以得出结论，无论是传统美白还是激光活化美白，都不会使牙齿易患龋损。
