Wen X, Zhang L, Liu R, Deng M, Wang Y, Liu L, Nie X
Oper Dent. 2014 May-Jun;39(3):273-82. doi: 10.2341/12-416-L. Epub 2013 Aug 6.
This study aims to evaluate the effects of pulsed Nd:YAG laser on the tensile bond strength (TBS) of resin to human enamel and caries resistance of human enamel. A total of 201 human premolars were used in this in vitro study. A flat enamel surface greater than 4 × 4 mm in area was prepared on each specimen using a low-speed cutting machine under a water coolant. Twenty-one specimens were divided into seven groups for morphology observations with no treatment, 35% phosphoric acid etching (30 seconds), and laser irradiation (30 seconds) of pulsed Nd:YAG laser with five different laser-parameter combinations. Another 100 specimens were used for TBS testing. They were embedded in self-cured acrylic resin and randomly divided into 10 groups. After enamel surface pretreatments according to the group design, resin was applied. The TBS values were tested using a universal testing machine. The other 80 specimens were randomly divided into eight groups for acid resistance evaluation. Scanning electron microscope (SEM) results showed that the enamel surfaces treated with 1.5 W/20 Hz and 2.0 W/20 Hz showed more etching-like appearance than those with other laser-parameter combinations. The laser-parameter combinations of 1.5 W/15 Hz and 1.5 W/20 Hz were found to be efficient for the TBS test. The mean TBS value of 14.45 ± 1.67 MPa in the laser irradiated group was significantly higher than that in the untreated group (3.48 ± 0.35 MPa) but lower than that in the 35% phosphoric acid group (21.50 ± 3.02 MPa). The highest mean TBS value of 26.64 ± 5.22 MPa was identified in the combination group (laser irradiation and then acid etching). Acid resistance evaluation showed that the pulsed Nd:YAG laser was efficient in preventing enamel demineralization. The SEM results of the fractured enamel surfaces, resin/enamel interfaces, and demineralization depths were consistent with those of the TBS test and the acid resistance evaluation. Pulsed Nd:YAG laser as an enamel surface pretreatment method presents a potential clinical application, especially for the caries-susceptible population or individuals with recently bleached teeth.
本研究旨在评估脉冲Nd:YAG激光对树脂与人类牙釉质拉伸粘结强度（TBS）以及人类牙釉质抗龋性的影响。本体外研究共使用了201颗人类前磨牙。在水冷条件下，使用低速切割机在每个标本上制备面积大于4×4mm的平整牙釉质表面。将21个标本分为七组，分别进行无处理、35%磷酸酸蚀（30秒）以及使用五种不同激光参数组合的脉冲Nd:YAG激光照射（30秒）以进行形态学观察。另外100个标本用于TBS测试。它们被嵌入自凝丙烯酸树脂中，并随机分为10组。根据分组设计对牙釉质表面进行预处理后，涂抹树脂。使用万能试验机测试TBS值。另外80个标本随机分为八组进行耐酸性评估。扫描电子显微镜（SEM）结果显示，与其他激光参数组合相比，1.5W/20Hz和2.0W/20Hz处理的牙釉质表面呈现出更多类似酸蚀的外观。发现1.5W/15Hz和1.5W/20Hz的激光参数组合对TBS测试有效。激光照射组的平均TBS值为14.45±1.67MPa，显著高于未处理组（3.48±0.35MPa），但低于35%磷酸组（21.50±3.02MPa）。在联合组（激光照射后再酸蚀）中确定了最高平均TBS值为26.64±5.22MPa。耐酸性评估表明，脉冲Nd:YAG激光在预防牙釉质脱矿方面有效。断裂牙釉质表面、树脂/牙釉质界面和脱矿深度的SEM结果与TBS测试和耐酸性评估结果一致。脉冲Nd:YAG激光作为一种牙釉质表面预处理方法具有潜在的临床应用价值，尤其适用于易感龋人群或近期牙齿漂白的个体。
