Department of Orthodontics, Hubei-MOST KLOS & KLOBM, School and Hospital of Stomatology, Wuhan University, Luoyu Road 237, 430079, Hongshan District, Wuhan, Hubei, People's Republic of China.
Department of Stomatology, The First Affiliated Hospital, Sun Yat-sen University, 510080, Guangzhou, Guangdong, People's Republic of China.
J Orofac Orthop. 2022 Mar;83(2):108-116. doi: 10.1007/s00056-021-00329-8. Epub 2021 Jul 26.
Fabricating resin bases has become an easy and economical method to achieve the customization of brackets. This study aimed to assess the effect of the resin base on bonding strength of spherical self-ligating brackets.
A defined amount of adhesive was bonded to the bracket base and constituted the new resin base. The thickness of the adhesive was measured and controlled at 0.5, 1.0, 1.5 and 2.0 mm, and a group without a resin base was used as a control. Sixty extracted human premolars were randomly divided into five groups. The brackets in each group were bonded to the specimen, and debonding tests were conducted. The shear bond strength (SBS) was calculated according to the measured debonding force in relation to the base area. The adhesive remnant index (ARI) score and the residual location of the fractured resin base were recorded. Enamel damage was also analyzed by scanning electron microscopy. After assessing for data normality and homogeneity, statistical comparisons between the groups and correlations among parameters were determined. P < 0.05 was regarded as significant.
The correlation analysis revealed an inverse correlation between the resin base thickness and the SBS (Coeff = -0.719, P < 0.01). The highest SBS was 9.33 MPa, in the control group, which was significantly greater than the lowest SBS (6.03 MPa), in the 2.0-mm group (P < 0.05). Multiple comparisons analysis revealed no differences in SBS between the 1.0-, 1.5- and 2.0-mm groups. Nonparametric analysis found that only the ARI score in the 0.5-mm group (2.92) was significantly different (P < 0.05) from that in the control group (1.25). As the thickness of the resin base increased, the fractured resin base tended to remain at the bracket base, and the risk of enamel damage decreased.
As the thickness of the resin base increased, the bonding strength of the spherical bracket decreased. However, the required clinical bonding strength was still satisfied when the thickness was less than 2.0 mm. The existence of a resin base could protect the enamel surface from damage caused by debonding. The customization of spherical brackets by tailoring a resin base can be applied in clinical practice because of the clinically acceptable bonding strength.
制作树脂基托已成为实现托槽定制的一种简便且经济的方法。本研究旨在评估树脂基托对球形自锁托槽粘结强度的影响。
在托槽基底部粘接一定量的粘结剂，构成新的树脂基托。测量并控制粘结剂的厚度为 0.5、1.0、1.5 和 2.0mm，并设无树脂基托组为对照组。将 60 颗离体人前磨牙随机分为 5 组，每组托槽粘结到标本上，并进行离解试验。根据测量的离解力与基底面的关系计算剪切粘结强度（SBS）。记录粘结剂残留指数（ARI）评分和断裂树脂基托的残留位置。扫描电子显微镜分析釉质损伤。评估数据正态性和同质性后，对组间进行统计学比较，并对参数进行相关性分析。P<0.05 为差异有统计学意义。
相关性分析显示，树脂基托厚度与 SBS 呈负相关（Coeff=-0.719，P<0.01）。对照组的最高 SBS 为 9.33MPa，显著高于 2.0mm 组的最低 SBS（6.03MPa，P<0.05）。多重比较分析显示，1.0、1.5 和 2.0mm 组之间的 SBS 无差异。非参数分析发现，只有 0.5mm 组的 ARI 评分（2.92）与对照组（1.25）显著不同（P<0.05）。随着树脂基托厚度的增加，断裂的树脂基托趋于保留在托槽基底部，釉质损伤的风险降低。
随着树脂基托厚度的增加，球形托槽的粘结强度降低。然而，当厚度小于 2.0mm 时，仍满足临床所需的粘结强度。树脂基托的存在可以保护釉质表面免受离解引起的损伤。通过定制树脂基托来定制球形托槽可以在临床实践中应用，因为其具有可接受的粘结强度。
