Special Laboratory of Lasers in Dentistry (LELO), Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil.
Lasers Med Sci. 2010 Nov;25(6):849-54. doi: 10.1007/s10103-009-0715-y. Epub 2009 Aug 6.
The purpose of this in vitro study was to evaluate the effect of etching time on the tensile bond strength (TBS) of a conventional adhesive bonded to dentin previously irradiated with erbium:yttrium-aluminum-garnet (Er:YAG) and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers. Buccal and lingual surfaces of 45 third molars were flattened until the dentin was exposed and randomly assigned to three groups (n = 30) according to the dentin treatment: control (not irradiated), irradiated with Er:YAG (1 W; 250 mJ; 4 Hz; 80.6 J/cm(2)) laser or Er,Cr:YSGG (4 W; 200 mJ; 20 Hz; 71.4 J/cm(2)) laser, and into three subgroups (n = 10) according to acid etching time (15 s, 30 s or 60 s) for each experimental group. After acid etching, the adhesive was applied, followed by the construction of an inverted cone of composite resin. The samples were immersed in distilled water (37 degrees C for 24 h) and subjected to TBS test [50 kilogram-force (kgf), 0.5 mm/min]. Data were analyzed by analysis of variance (ANOVA) and Tukey statistical tests (P < or = 0.05). Control group samples presented significant higher TBS values than those of all lased groups. Both irradiated groups exhibited similar TBS values. Samples subjected to the different etching times in each experimental group presented similar TBS. Based on the conditions of this in vitro study we concluded that Er:YAG and Er,Cr:YSGG laser irradiation of the dentin weakens the bond strength of the adhesive. Moreover, increased etching time is not able to modify the bonding strength of the adhesive to irradiated dentin.
钇-铝-石榴石（Er:YAG）和铒、铬：钇-钪-石榴石（Er,Cr:YSGG）激光辐照的牙本质进行常规粘结的粘结强度（TBS）的影响。45 颗第三磨牙的颊面和舌面被磨平，直到暴露牙本质，并根据牙本质处理随机分为三组（n = 30）：对照组（未辐照）、用 Er:YAG（1 W；250 mJ；4 Hz；80.6 J/cm(2)) 激光或 Er,Cr:YSGG（4 W；200 mJ；20 Hz；71.4 J/cm(2)) 激光辐照，然后根据每组实验的酸蚀时间（15 s、30 s 或 60 s）分为三个亚组（n = 10）。酸蚀后，应用粘结剂，然后构建倒置复合树脂锥形。样本浸入蒸馏水中（37°C 24 h），进行 TBS 测试[50 千克力（kgf），0.5 mm/min]。数据分析采用方差分析（ANOVA）和 Tukey 统计检验（P < or = 0.05）。对照组样本的 TBS 值明显高于所有激光照射组。两组照射组的 TBS 值相似。每组不同酸蚀时间的样本具有相似的 TBS 值。根据本体外研究的条件，我们得出结论，Er:YAG 和 Er,Cr:YSGG 激光辐照牙本质会削弱粘结剂的粘结强度。此外，增加酸蚀时间不能改变粘结剂对辐照牙本质的粘结强度。
