Nd:YAG激光辅助去除陶瓷托槽对托槽的粘接强度及髓腔温度影响的研究

目的　研究国产DL-200型计算机控制脉冲Nd:YAG口腔激光机去除陶瓷托槽的最佳技术参数。方法　观察未使用激光照射组,以及激光功率5 W、照射时间2 s组,功率3 W、照射时间3 s组和功率2 W、照射时间5 s 组,3种参数下激光对陶瓷托槽的粘接强度及髓腔温度的影响。结果　①激光照射后可以显著降低陶瓷托槽的粘接强度,约降低50%,4组间的平均粘接强度差异有统计学意义(P<0·001);②激光照射后各组髓腔温度均升高,各组温度升高有统计学意义(P<0·001),激光功率3 W、照射时间3 s组髓腔温度只升高3·65℃,较其他两组低。结论　国产DL-200型计算机控制脉冲Nd:YAG口腔科激光治疗机激光照射后可以显著降低陶瓷托槽的粘接强度,去除陶瓷托槽的最佳参数是激光功率3 W、照射时间3 s,这一能量不会明显升高牙髓温度。     

Nd：YAG激光去除陶瓷托槽对兔牙髓组织的影响

目的应用Nd：YAG激光,观察在不同功率、时间等参数下,激光照射辅助去除陶瓷托槽后兔牙髓的组织学变化。方法选择新西兰长耳白兔20只,将其4颗前牙作为实验用牙齿,常规黏结陶瓷托槽。左上前牙机械去黏结,作为对照组;其余3颗牙齿采用激光去黏结,右上前牙激光能量为3 W、3 s（A组）,左下前牙能量为2 W、5 s（B组）,右下前牙能量为5 W、2 s（C组）。去黏结后5 min、1 d、3 d、1周和1月后处死动物,每次处死4只,拔除前牙,制作兔牙髓组织切片。结果与对照组相比,经不同能量激光照射后5 min,兔牙髓组织均出现轻度毛细血管扩张。1 d后,A、B组出现中度毛细血管扩张;C组除有中度毛细血管扩张外,还伴有少量炎细胞浸润。3 d后,B组牙髓症状消失;A组牙髓症状减轻,仍有轻度毛细血管扩张;C组有毛细血管扩张、出血,并伴有炎细胞浸润。1周后,A组毛细血管扩张减轻,基本恢复正常;C组症状仍很明显。1月后,A组牙髓症状消失,C组仍有轻度毛细血管扩张。结论采用能量为3 W、3 s的Nd：YAG激光去除陶瓷托槽,兔牙髓组织不会出现不可逆的组织学变化。     

Scanning electron microscope comparative surface evaluation of glazed-lithium disilicate ceramics under different irradiation settings of Nd:YAG and Er:YAG lasers

Objective:To evaluate the surface of glazed lithium disilicate dental ceramics after irradiation under different irradiation settings of Nd:YAG and Er:YAG lasers using a scanning electron microscope (SEM).Materials and Methods:Three glazed-press lithium disilicate ceramic discs were treated with HF, Er:YAG, and Nd:YAG, respectively. The laser-setting variables tested were laser mode, repetition rate (Hz), power (W), time of exposure (seconds), and laser energy (mJ). Sixteen different variable settings were tested for each laser type, and all the samples were analyzed by SEM at 500× and 1000× magnification.Results:Surface analysis of the HF-treated sample showed a typical surface texture with a homogenously rough pattern and exposed ceramic crystals. Er:YAG showed no effect on the surface under any irradiation setting. The surface of Nd:YAG-irradiated samples showed cracking, melting, and resolidifying of the ceramic glaze. These changes became more pronounced as the power increased. At the highest power setting (2.25 W), craters on the surface with large areas of melted or resolidified glaze surrounded by globules were visible. However, there was little to no exposure of ceramic crystals or visible regular surface roughening.Conclusions:Neither Er:YAG nor Nd:YAG dental lasers exhibited adequate surface modification for bonding of orthodontic brackets on glazed lithium disilicate ceramics compared with the control treated with 9.5% HF.     

Shear bond strength of rebonded brackets after removal of adhesives with Er,Cr:YSGG laser

This study was conducted to examine the bond strength of rebonded orthodontic brackets after adhesive residuals on the surface of the bracket bases were removed by Er,Cr:YSGG lasers. Seventy-six brackets bonded to premolars with a self-etching primer adhesive system were equally divided into four groups after the first debonding with the bracket bases (Group 1) untreated, and treated by (Group 2) Er,Cr:YSGG laser, (Group 3) sandblaster, and (Group 4) Er,Cr:YSGG laser/sandblaster. The treated brackets were rebonded to the new premolars in the same manner as the first-stage experiment. The shear bond strengths were measured, with the bonding/debonding procedures repeated once after the first debonding, and the bracket/adhesive failure modes were evaluated after each debonding. The treated bracket base surfaces were observed under a scanning electron microscopy (SEM). The mean rebond strengths were significantly lower in group 1 than in other groups, and there were no significant differences between the other groups. The mean initial bond strength was significantly higher than the mean rebond strength in group 1 but there was no significant difference between the two in the other three groups. Failures at the bracket-adhesive interface occurred frequently at second debonding in group 1. Under the SEM, residual adhesive was removed from the bracket bases by Er,Cr:YSGG laser, while adhesive remnant was seen underneath the meshwork of the bracket bases and microroughness appeared on the meshwork after sandblasting. Er,Cr:YSGG laser certainly could serve the purpose of promoting the use of recycled orthodontic brackets.     

钛表面3种不同处理方法对钛-瓷结合影响的对比研究

目的对比钛表面分别经微弧氧化和Nd:YAG激光处理、喷砂处理后的表面形貌、理化性能的差异,比较其对钛瓷结合强度的影响。方法将60个规格为25.0 mm×5.0 mm×0.5 mm的标准钛片试件,随机均分为3组,每组20片(A组为微弧氧化组,B组为激光轰击组,C组为喷砂组),运用扫描电镜、X射线衍射仪、EDS等分析其形貌和物相;三点弯曲实验测试钛瓷结合强度并进行统计学分析比较。结果 A、B、C 3组试件的钛瓷结合强度均高于ISO9693要求的25 MPa,Nd:YAG激光处理试件钛瓷结合强度较微弧氧化处理高,且两者均高于喷砂组。结论 3种处理方式都能提高钛表面的钛瓷结合强度,Nd:YAG激光处理后效果优于微弧氧化和喷砂处理。     

激光表面处理对树脂粘接剂与Y-TZP陶瓷冠粘接强度的影响

目的：为评估不同的表面处理方式对树脂粘接剂和Y-TZP粘接强度的影响。方法：制作直径10mm,厚度0.7mm的盘状Y-TZP氧化锆试件60个,并在其表面上饰瓷,Vita VM9饰面瓷的厚度为1.5mm。所有试样分为6组,对照组不进行任何处理;涂层组-烧结前进行化学硅烷涂层（30-μm SiO2）;打磨组-烧结前使用50-μm Al2O3进行空气打磨;激光组-Er：YAG激光组,Nd：YAG激光组,CO2激光组。试样制作完成后将复合树脂粘接到陶瓷上。应用万能试验机测量全瓷修复体与树脂的平均剪切粘接强度（MPa）。使用one-wayANOVA对表面处理方法的影响进行统计学分析,通过Tukey HSD检验进行多重比较（α=0.05）。结果：各组的平均剪切粘接强度（MPa）分别：对照组=14.3±0.8;涂层组=14.9±0.9;打磨组=20.6±1.0;Er：YAG激光组=26.1±1.5;Nd：YAG激光组=27.2±1.3;CO2激光组=26.6±1.2。不同的表面处理方法对复合树脂与全瓷修复体的剪切粘接强度的影响六组间差异有统计学意义（P〈0.01）。激光组、打磨组与对照组间差异有统计学意义,涂层组与对照组间差异无统计学意义。结论：硅烷涂层处理不能提高复合树脂与Y-TZP间的剪切粘接强度。空气打磨和激光照射能提高复合树脂与Y-TZP间的剪切粘接强度。     

Nd: YAG激光对3种树脂水门汀与牙本质粘接强度的影响

目的观察Nd: YAG激光照射前后树脂水门汀-牙本质粘接界面的微观形貌特征,评价Nd: YAG激光对3种树脂水门汀与牙本质间粘接强度的影响。方法选择人离体前磨牙30颗,分为颊、舌两部分,将试件随机分为激光组和对照组。激光组以0.8 W、10 Hz脉冲Nd: YAG激光作用于牙本质表面25 s,联合3种树脂水门汀RelyX ARC、Panavia F和RelyX Unicem充填;对照组直接使用树脂水门汀充填。然后测试剪切强度,在根管显微镜下观察断裂模式并分类。另选人离体前磨牙6颗,按照标准的牙本质粘接面预备后,使用Nd: YAG激光照射3颗牙牙本质表面,并联合充填不同的树脂水门汀,用扫描电镜观察Nd: YAG激光照射前后树脂水门汀-牙本质界面的微观形貌变化。结果
激光照射可以提高自酸蚀树脂水门汀Panavia F和自粘接树脂水门汀RelyX Unicem与牙本质之间的剪切强度（P＜0.05）。激光会降低全酸蚀树脂水门汀RelyX ARC与牙本质间的剪切强度（P＜0.05）。根管显微镜下观察可见：试件断裂大部分发生在树脂水门汀-牙本质界面。扫描电镜观察可见：Nd: YAG激光照射后,全酸蚀亚组和自酸蚀亚组的混合层变薄、树脂突变短且少;自粘接亚组变化不明显,未见树脂突。结论Nd: YAG激光照射后,可提高Panavia F和RelyX Unicem与牙本质的剪切强度,建议临床联合应用。     

Bond strength and debonding characteristics of a new ceramic bracket

INTRODUCTION: The purposes of this study were to evaluate the shear bond strength of a new collapsible monocrystalline bracket (Inspire, Ormco, Orange, Calif) and compare it with another collapsible ceramic bracket (Clarity, 3M Unitek, Monrovia, Calif) and a metal bracket; to examine the modes of failure after shear bond strength testing; and to observe the tooth surface after debonding the ceramic brackets with pliers. METHODS: One hundred extracted human premolars were selected for bonding. Three types of brackets and 2 orthodontic adhesives (Transbond XT, 3M Unitek; and Enlight, Ormco) were used. After bonding, all samples were placed in a distilled water bath at 37 degrees C for 24 hours. The shear bond strength of 60 samples was measured, and the remaining 40 samples with ceramic brackets were debonded with pliers. RESULTS: No statistically significant differences in bond strengths among the different combinations of brackets and adhesives were found (P > .05). The mode of failure after debonding by either shear bond strength testing or with pliers was predominantly at the bracket/adhesive interface in all groups. Enamel and bracket fractures were noted in 2 and 5 of 20 samples for Inspire, and 1 and 0 of 20 samples for Clarity after debonding with pliers. CONCLUSIONS: Bond strength and mode of failure of Inspire were similar to those of Clarity, but the risk of bracket fracture after debonding for Inspire was greater.     

Tensile bond strength of ceramic brackets bonded to porcelain facets.

The number of adults requesting orthodontic treatment is constantly growing, with a resultant increase in the need to bond brackets to porcelain restorations. Because adults often favor more esthetic ceramic brackets, it is important to evaluate the bond strength of ceramic to porcelain restorations and the integrity of the porcelain surface after debonding. Eighty porcelain facets, resembling mandibular incisors, were used. The surfaces were conditioned by either hydrofluoric acid or microetching. Mandibular incisor ceramic brackets were bonded with 1 of 2 adhesives: Ideal 1 without silane or Right-On with silane. Debonding was performed with a tensile force on a universal testing machine. The mode of bond failure was determined macroscopically, and the integrity of the porcelain facets was evaluated microscopically. The results showed that the type of porcelain conditioning technique affects the tensile bond strength of both adhesives. Conditioning with hydrofluoric acid resulted in significantly higher bond strength (Ideal 1, 7.7 +/- 3.0; Right-On, 7.1 +/- 2.6) than conditioning by microetching (Ideal 1, 4.1 +/- 2.3; Right-On, 3.8 +/- 2.4; P <.05). The mode of bond failure was mainly adhesive, and the porcelain facets were not damaged during debonding. This study shows that both Ideal 1 and Right-On are suitable for bonding ceramic brackets to porcelain restorations, if the porcelain has been conditioned with hydrofluoric acid.     

Conditioning of Enamel with Nd:YAG and CO2 Dental Laser Systems and with Phosphoric Acid An In-Vitro Comparison of the Tensile Bond Strength and the Morphology of the Enamel Surface

MATERIAL AND METHOD 1: The first stage of a three-stage in-vitro investigation used 146 maxillary incisors to identify optimum setting parameters for two CO2 and Nd:YAG standard laser systems applied in enamel conditioning for bracket bonding. RESULTS: 31 of the 75 parameter combinations investigated for the Nd:YAG laser and nine of the 71 investigated for the CO2 laser proved appropriate for further investigation of tensile strength. MATERIAL AND METHOD 2: In a second stage, tensile bond strength for the selected laser settings was determined in comparison to the conventional acid-etch technique for a further 210 teeth as the control group. RESULTS: The highest average tensile strength for the Nd:YAG laser was 4.1 MPa, with comparable values of 3.3 MPa for the CO2 Laser and 4.9 MPa for the acid-etch technique. MATERIAL AND METHOD 3: The third stage of the investigation involved comparative scanning electron microscopy of enamel surface morphology following laser application and acid-etching. RESULTS: The CO2 laser was found to produce craters of various dimensions, while the Nd:YAG laser produced honeycomb structures regionally similar to enamel samples from the acid-etch technique. CONCLUSION: The CO2 and Nd:YAG dental lasers tested produce enamel conditioning and tensile bond strength sufficient to meet the requirements of bracket bonding.     

机械法去除国产陶瓷托槽安全性的研究

目的使用去托槽钳去除两种底板设计的国产多晶体氧化铝陶瓷托槽,评价对牙齿安全性的影响。方法选择离体上、下颌各15颗双尖牙,随机分为3组。实验组为国产沟槽底板（3条横沟）和网格底板（3×3网格）陶瓷托槽,对照组为临床常用多晶体氧化铝陶瓷托槽（Crystaline IV）。使用37%液体磷酸和京津釉质粘接剂分别粘接上述3种托槽,在0.9%生理盐水中室温保存24h。使用去托槽钳及WDW3050型微机控制电子万能试验机龈向施加剪切力,检测去除强度、粘接剂残留指数（ARI）及托槽断裂个数,并以立体显微镜评价釉质表面损伤情况。结果国产沟槽底板、网格底板陶瓷托槽及Crystaline IV的去除强度分别为18.49±4.00MPa、17.89±4.13MPa和17.62±4.51MPa,三者间无显著性差异。主要去除部位均在粘接剂内部,托槽断裂个数分别为7个、7个和6个。各有一颗使用国产沟槽底板陶瓷托槽和Crystaline IV的牙齿在立体显微镜下发现明显的釉质缺损。结论对于唇面呈弧形的牙体,使用去托槽钳龈向施加剪切力去除国产多晶体氧化铝陶瓷托槽时,去除强度大,易发生托槽断裂,且可能并发釉质剥脱,并不是理想方法。     

Effects of Nd:YAG lasers on root canal walls: a light and scanning electron microscopic study.

OBJECTIVE: This study evaluated amounts of debris, smear layer, and recrystallized dentin on root canal walls treated with an Nd:YAG laser. The presence of carbonized material was also assessed. METHOD AND MATERIALS: The root canals of 36 extracted incisors were prepared by stepdown and stepback techniques and divided into 4 groups. One group was not treated further, while 3 others were exposed to the laser beam at an energy density of 159, 239, or 318 J/cm2. The roots were split longitudinally, photographed, and examined using a scanning electron microscope. The amounts of debris, smear layer, and recrystallized dentin were recorded from horizontal bands around the root, 2, 6, and 10 mm from the apices. RESULTS: Mean smear layer scores were similar for all groups at the 3 levels examined, ranging from 2.157 to 2.851 on a scale of 0.0 to 3.0. Mean debris scores were similar for all groups at the 3 levels examined, ranging from 0.774 to 1.408 on a scale of 0.0 to 3.0. Recrystallized dentin was recorded in all 3 irradiated groups at the 2-mm level, but only in the group irradiated with 318 J/cm2 at the 6- and 10-mm levels. Severe carbonization was recorded at the 2-mm level. CONCLUSION: Use of the Nd:YAG laser did not reduce the mean amounts of debris and smear layer compared to a nonirradiated group. Carbonization was recorded in the apical part of the canal, but this is not obvious when only scanning electron photomicrographs are examined.     

Er:YAG激光不同能量预处理对自粘结树脂水门汀剪切粘结强度的影响

目的探讨Er:YAG激光不同能量预处理对自粘结树脂水门汀剪切粘结强度的影响。方法按照纳入标准收集人离体磨牙70颗,根据对牙本质表面Er:YAG激光预处理能量的不同随机分为7组:A组(空白对照)、B组(50 m J,10 Hz)、C组(100 m J,10 Hz)、D组(150 m J,10 Hz)、E组(200 m J,10 Hz)、F组(250 m J,10 Hz)、G组(300 m J,10 Hz)。每组10颗牙中随机取2颗切取3 mm厚的牙本质片,按相应分组用不同激光能量预处理后扫描电镜观察;每组剩余8颗牙包埋后,制备一致标准牙本质表面,按相应分组要求预处理后,用自粘结树脂水门汀Rely XTMUnicem将其与Everest ZS氧化锆瓷片粘结,24 h后测试各组剪切粘结强度并进行统计学分析。结果扫描电镜观察显示Er:YAG激光预处理后牙本质表面形态改变明显,变得粗糙不平,牙本质小管开放,无玷污层,管周和管间牙本质脱矿,一定能量范围内呈现较好的粘结表面;剪切粘结强度结果显示Er:YAG激光预处理可增强自粘结树脂水门汀Rely XTMUnicem的剪切粘结强度(P<0.01);C、D、E组的剪切粘结强度与A组有显著性差异(P<0.05)。结论粘结强度与牙本质的粘结表面密切相关,合适能量下的Er:YAG激光预处理能获得较好的牙本质粘结表面,提高自粘结树脂与牙本质和氧化锆瓷的剪切粘结强度。     

Comparison of the debonding characteristics of two innovative ceramic bracket designs.

Two new ceramic brackets-one designed with a metal-lined arch wire slot and the other with an epoxy resin base-have been recently introduced. The new brackets are thought to combine the esthetic advantages of ceramics and the functional advantages of debonding metal brackets. The purpose of this study was to compare the following: 1) the shear bond strength of the 2 brackets, and 2) the bond failure location when the brackets are debonded with pliers. Sixty-one Clarity (3M Unitek) collapsible ceramic brackets and 66 MXi (TP Orthodontics, Inc) brackets were bonded to the teeth with the same bonding system. The Zwick Universal Test Machine (Zwick Gm bH & Co) was used to determine the shear bond strength force levels needed to debond the brackets. The appropriate pliers also were used to debond both types of brackets to determine the mode of bond failure that will be encountered clinically. After debonding, all the teeth and brackets were examined with 10x magnification. Any adhesive that remained after the bracket removal was assessed according to the Adhesive Remnant Index. The findings indicated that the shear bond strength of the Clarity ceramic brackets was significantly greater than that of the MXi ceramic brackets. However, both brackets exhibited forces that were adequate for clinical use. The Adhesive Remnant Index scores for both the shear test and the plier debonding indicated a similar bond failure pattern when the 2 ceramic brackets were compared with each other. This suggests that, when these brackets are debonded with the Weingart (Ormco) and ETM (Ormco) pliers, there was a greater tendency for most of the adhesive to remain on the enamel surface. In conclusion, the most efficient method to debond the MXi ceramic bracket is by placing the blades of the ETM 346 pliers between the bracket base and the enamel surface. On the other hand, the most efficient method of debonding the Clarity bracket is by using the Weingart pliers and applying pressure to the tiewings. When the 2 ceramic brackets were debonded as recommended here, most of the residual adhesive remained on the enamel surface, a pattern similar to the one observed previously with metal brackets. The failure at the bracket-adhesive interface decreases the probability of enamel damage but necessitates the removal of more residual adhesive after debonding.     

不同能量密度Nd:YAG激光照射对牙本质粘接强度的影响

目的:研究不同能量密度下Nd:YAG激光照射对牙本质粘接强度的影响。方法:36颗无龋第三磨牙去除冠方牙釉质,随机分为3组:对照组低能量密度激光照射组(1 W,85 J/cm²)和高能量密度激光照射组(4 W, 350 J/cm²)。每组牙再随机分为两个亚组,分别使用全酸蚀(Single Bond 2)或自酸蚀粘接剂(G-Bond)进行粘接以及树脂修复。进行微拉伸粘接强度测试,扫描电镜观察牙本质表面形貌及粘接界面纳米渗漏情况。激光扫描共聚焦荧光显微镜下观察粘接界面树脂突形态及数量。结果:全酸蚀粘接中,低密度激光照射对粘接强度无影响,高密度激光照射后粘接强度相比对照组降低(P<0.05);自酸蚀粘接中,低密度激光照射后粘接强度比对照组显著下降(P<0.05),高密度激光照射对粘接强度无影响。低密度激光照射不增加粘接界面纳米渗漏,高密度激光照射后样本纳米渗漏相比对照组均显著增加(P<0.05)。结论:低能量密度的激光照射后使用全酸蚀粘接系统粘接效果较好;高能量密度的激光照射后使用自酸蚀粘接系统效果较好。     

Comparisons of shear bond strength of precoated and uncoated brackets

In an attempt to save chairside time during bonding, orthodontists are using ceramic and metal brackets that have been precoated with the adhesive material. The adhesive used on the precoated brackets is similar in composition to that used for bonding uncoated brackets; the difference is essentially in the percentages of the various ingredients incorporated in the material. The purpose of this study is to determine whether these changes in composition affect the shear bond strength and the site of bond failure when precoated and uncoated ceramic and metal brackets are used. Eighty-five recently extracted human molars were bonded according to the manufacturer's instructions and mounted in phenolic rings. An occlusogingival load was applied to the bracket, producing a shear force at the bracket-tooth interface with a Zwick Universal Test Machine. After debonding, all teeth and brackets were examined under 10× magnification. Any adhesive remaining after bracket removal was assessed with the Adhesive Remnant Index (ARI). The current findings indicated that: (1) Precoated ceramic brackets that used a slightly modified adhesive have similar shear bond strengths as that provided by Transbond XT adhesive on uncoated brackets; (2) precoated metal brackets that used the same adhesive have significantly lower shear bond strength than those obtained with Transbond XT on uncoated brackets. The differences in the bond strength between the ceramic and metal brackets were attributed to the combined effects of the changes in the composition of the adhesives used and in the retention mechanisms incorporated in the bracket bases of the different types of brackets; (3) all bracket/adhesive combinations tested provided clinically acceptable shear bond forces. (Am J Orthod Dentofac Orthop 1997;112:617-21.)     

Nd:YAG激光在瓷修补表面处理中应用的实验研究

目的:探讨Nd:YAG激光在瓷修补表面处理中的应用。方法:用合金试样模拟崩瓷后烤瓷冠基底,应用Nd:YAG激光进行处理,处理结果用扫描电镜观察,并与对照组相比较。处理后试样用瓷修补材料修补后,进行剪切实验,测试结果进行t检验,观察试样断裂模式及断口形貌。结果:激光组合金表面形成脉冲点状结构,与喷砂组表面形貌差异显著。激光组剪切强度高于对照组,二者差异有显著性(P<0.05)。断裂模式显示喷砂组试样全部呈现粘结型断裂,而激光组有3例试样呈现混合型断裂,试样部分断裂点位于修补材料自身。结论:Nd:YAG激光用于瓷修补时合金基底的表面处理,可增加被处理表面的粗糙度。     

Nd:YAG激光轰击处理纯钛表面对钛-瓷结合强度影响的实验研究

目的: 探讨Nd:YAG激光处理对纯钛表面形貌、理化性能以及钛-瓷结合强度的影响。方法: 将30个纯钛试片表面用碳化硅砂纸打磨后得到规格为25 mm×3 mm×0.5 mm的标准试件,随机均分为3组,A 组为喷砂组,B组为激光处理15 s组,C组为激光处理30 s组,测量各组的表面粗糙度值和金属-蒸馏水表面接触角。钛表面烤瓷,测试钛-瓷间的三点弯曲结合强度并统计学分析,用扫描电镜观察纯钛处理后的表面形貌和钛-瓷分离面的表面形貌以及EDS分析。结果: 3组钛-瓷结合强度在统计学上有显著差异(P<0.001),B组钛-瓷结合强度高于A组(P<0.05),且小于C组(P<0.05)。结论: 钛表面Nd:YAG激光处理后可有效提高钛-瓷的结合强度。     

Thermal debracketing of single crystal sapphire brackets.

Because of their optical clarity, single crystal sapphire brackets provide an esthetic advantage over many other types of orthodontic brackets. However, debonding of these brackets has caused iatrogenic damage to enamel. Thermal debonding has been proposed for use in removing sapphire brackets without causing damage to teeth. This study determined the temperature required at the enamel/resin interface to thermally debond sapphire brackets from etched bovine enamel using 23 different commercially available orthodontic resins and one experimental product. The results indicate a wide range of debonding temperatures for the various resins. As a group, the powder-liquid materials had a statistically lower debonding temperature than the two-paste, the no-mix products, or the light-cured materials, for which the temperatures were all similar. This paper presents relative information a clinician can use in selecting an orthodontic bonding resin to minimize thermal damage to the teeth while debonding sapphire brackets.     

脉冲激光辅助去除正畸金属托槽方法初探

目的 探讨脉冲Nd:YAG激光辅助去除正畸金属托槽的可行性,以期为临床提供一种优于机械性去除金属托槽的方法.方法 选择因正畸治疗拔除的50颗前磨牙,粘接托槽后根据随机数字表随机分为5组,每组10颗,实验1-4组分别接受13.0、13.5、14.0、14.5 A电流强度的激光照射,同时给予4.9 N的外力,直至托槽脱落,记录托槽脱落时间及牙髓腔内温度;剩余1组为对照组,使用持针器去除托槽.在体视显微镜下测量并计算粘接剂残留指数(adhesive remnant index,ARI).扫描电镜观察各组釉质表面情况.结果 实验1-4组的托槽脱落时间分别为(67.70 4±7.18)、(35.90±4.28)、(24.90 ±3.76)、(6.90±2.33)s.各组间差异均有统计学意义(P<0.01).实验1-4组牙髓腔内温度分别升高(20.97±3.10)、(12.75±3.14)、(8.99±2.47)、(2.91±1.88)℃,各组间差异均有统计学意义(P<0.05).实验1-4组和对照组Arl分别为(8.55±5.02)%、(15.42±7.37)%、(5.55±3.79)%、(13.72±6.69)%和(74.36±29.44)%,两两比较显示对照组与不同实验组间差异均有统计学意义(P<0.05),实验1-4组间差异无统计学意义(P>0.05).扫描电镜下可见对照组釉面横纹已被破坏,釉质表面粗糙不平;实验组釉质表面清洁,未见划痕、弹坑样及蜂窝样改变.结论 脉冲Nd:YAG激光辅助去除正畸金属托槽是一种可行的方法;与机械法相比,脉冲Nd:YAG激光辅助去除托槽及粘接剂的过程不破坏釉质表面结构.