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。

Safety evaluation of debonding domestic ceramic brackets with bracket-removal plier in vitro

Objective To measure the force needed to debond two kinds of domestic ceramic brackets and to evaluate the effects of debonding force on teeth.Methods Thirty extracted human premolars were divided into 3 groups.The experimental groups used domestic ceramic brackets of different base design,groove base(three horizontal groove) and gridding base(3×3).The control group was Crystaline IV.The ceramic brackets were bonded with 37% phosphoric-acid and Dental Enamel Bonding Resin(made in China) and debonded with bracket-removal pliers.The experiment was conducted with DWD3050 electronic testing machine to measure the force needed to remove the bracket.After debonding the adhesive remnant index(ARI) and the number of brackets facture were recorded,and the tooth was examined with stereomicroscope.Results The debonding strength of groove base,gridding base and Crystaline IV were 18.49±4.00MPa,17.89±4.13MPa and 17.62±4.51MPa,respectively,which were not significantly different.The bonding failure was mostly located in cement.The numbers of fractured brackets were 7,7 and 6 respectively.Apparent enamel damages were observed under stereomicroscope in two teeth.Conclusion To remove domestic ceramic brackets with pliers was not appropriate for teeth with curved facial surface.