Toodehzaeim Mohammad Hossein, Khanpayeh Elham
Associate Professor, Department of Orthodontics, Faculty of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
Assistant Professor, Department of Orthodontics, Faculty of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
J Dent (Tehran). 2015 Apr;12(4):257-62.
The purpose of this study was to evaluate the effect of salivary pH on the shear bond strength (SBS) of orthodontic brackets to tooth surface.
Eighty intact premolars were randomly divided into four groups of 20. After bonding a bracket on each tooth, the groups one to four were stored in artificial saliva at a pH of 3.8, 4.8, 5.8, and 6.8, respectively for two months. The artificial saliva solutions were refreshed weekly. Each tooth was then embedded in an acrylic block so that the crown was exposed and its buccal surface was parallel to the direction of the force during SBS testing. All brackets were debonded using Dartec universal testing machine, and the mean values of SBS in different groups were compared using one-way analysis of variance (ANOVA).
The mean SBS value in group one (pH 3.8) was significantly lower than that in other groups (P<0.05). The differences between other groups were not significant (P>0.05).
Decreased salivary pH due to poor oral hygiene and/or frequent consumption of acidic beverages may be responsible for orthodontic bracket bond failure.
本研究旨在评估唾液pH值对正畸托槽与牙面之间剪切粘结强度（SBS）的影响。
80颗完整的前磨牙被随机分为四组，每组20颗。在每颗牙齿上粘结一个托槽后，第一组至第四组分别在pH值为3.8、4.8、5.8和6.8的人工唾液中储存两个月。人工唾液溶液每周更换一次。然后将每颗牙齿嵌入丙烯酸块中，使牙冠暴露，并且在进行SBS测试时其颊面与力的方向平行。使用Dartec万能试验机使所有托槽脱粘，并使用单因素方差分析（ANOVA）比较不同组中SBS的平均值。
第一组（pH 3.8）的平均SBS值显著低于其他组（P<0.05）。其他组之间的差异不显著（P>0.05）。
口腔卫生不良和/或频繁饮用酸性饮料导致的唾液pH值降低可能是正畸托槽粘结失败的原因。
