Bishara S E, Vonwald L, Zamtua J, Damon P L
College of Dentistry, University of Iowa, Iowa City 52242, USA.
Am J Orthod Dentofacial Orthop. 1998 Aug;114(2):150-3. doi: 10.1053/od.1998.v114.a84780.
Chlorhexidine has been applied on the teeth and over orthodontic appliances during treatment in order to reduce bacterial colonization. The purpose of this study was to determine whether the application of chlorhexidine with or without a sealant, to the etched enamel will affect the shear bond strength and the bracket/adhesive failure modes of orthodontic brackets. A total of 132 extracted third molars were cleaned and then divided into 6 groups of at least 20 teeth each. The teeth were etched with a 37% phosphoric acid gel and a sealant was applied in 5 of the groups. Stainless steel orthodontic brackets were then bonded with the Transbond XT bonding system. The chlorhexidine was applied to the teeth either as a prophylactic paste or as a varnish under the following conditions: (1) as a varnish over the bracket and tooth surfaces after the bonding procedure was completed; (2) as a prophylactic paste containing 0.12% chlorhexidine over the intact enamel i.e., before etching; (3) mixed with the sealant and applied to the etched enamel before bonding, (4) as a varnish applied to the etched enamel with no sealant used; (5) as a varnish over the light cured sealant; and (6) as a varnish over the sealant before the sealant was light cured. All teeth were mounted in phenolic rings and stored in deionized water at 37 degrees C for 48 hours. A Zwick Universal Testing Machine was used to determine shear bond strengths. The residual adhesive on the enamel surface was evaluated with the Adhesive Remnant Index. The analysis of variance and chi square tests were used to compare the six groups. Significance was predetermined at the p < or = 0.05. The findings in this study indicated that shear bond strength was not significantly affected when chlorhexidine was applied; (1) over the bracket and tooth surfaces after the bonding procedure was completed (mean = 12.3 +/- 3.1 MPa), (2) as a prophylactic paste over the unetched enamel surface before the bonding procedure is initiated (mean = 9.6 +/- 2.3 MPa), and (3) when the varnish was premixed with the sealant and applied on the etched enamel surface (mean 11.8 +/- 2.1 MPa). On the other hand, in all the experimental groups in which the chlorhexidine varnish was applied as a layer on the etched enamel surface or over the sealant, shear bond strength values and bracket failure rates were of a magnitude that made them clinically unacceptable.
在正畸治疗过程中，洗必泰已被应用于牙齿及正畸矫治器上，以减少细菌定植。本研究的目的是确定在酸蚀釉质上应用洗必泰（无论有无封闭剂）是否会影响正畸托槽的剪切粘结强度以及托槽/粘结剂的失效模式。总共132颗拔除的第三磨牙被清洁后，分成6组，每组至少20颗牙。用37%的磷酸凝胶酸蚀牙齿，其中5组应用了封闭剂。然后用Transbond XT粘结系统粘结不锈钢正畸托槽。洗必泰以预防糊剂或清漆的形式在以下条件下应用于牙齿：（1）在粘结程序完成后，作为清漆涂覆在托槽和牙齿表面；（2）作为含0.12%洗必泰的预防糊剂涂覆在完整釉质上，即在酸蚀前；（3）与封闭剂混合并在粘结前涂覆于酸蚀釉质上；（4）作为清漆涂覆于酸蚀釉质上，未使用封闭剂；（5）作为清漆涂覆在光固化封闭剂上；（6）在封闭剂光固化前，作为清漆涂覆在封闭剂上。所有牙齿被安装在酚醛环中，并在37℃的去离子水中储存48小时。使用Zwick万能试验机测定剪切粘结强度。用粘结剂残留指数评估釉质表面的残留粘结剂。采用方差分析和卡方检验比较这6组。显著性预先设定为p≤0.05。本研究结果表明，当应用洗必泰时，剪切粘结强度未受到显著影响：（1）在粘结程序完成后，涂覆在托槽和牙齿表面（平均值=12.3±3.1MPa）；（2）在粘结程序开始前，作为预防糊剂涂覆在未酸蚀的釉质表面（平均值=9.6±2.3MPa）；（3）当清漆与封闭剂预混合并涂覆在酸蚀釉质表面时（平均值11.8±2.1MPa）。另一方面，在所有将洗必泰清漆作为一层涂覆在酸蚀釉质表面或封闭剂上的实验组中，剪切粘结强度值和托槽失败率均处于临床不可接受的水平。
