Mean Shearing Stroke Frequency of Orthodontic Brackets under Cycling Loading: An In Vitro Study

Abstract

Based on the development of many adhesive systems and bonding techniques, bonding strength of orthodontic brackets has become even more important in modern clinical orthodontics. The aim of this study was to determine mean shearing stroke frequency of different orthodontic bracket types and bonding agents under cycling loading. Therefore, 10 different types of orthodontic bracket from 4 different brands were divided into 2 groups. Two different adhesives, namely Transbond™ XT etch-and-rinse for Group 1 and Transbond™ Plus self-etching-primer adhesive for Group 2 were considered. The brackets were tested under cycling loading force of 10-N and a crosshead speed of 300 mm/min and 40 cycle/min. The frequency of strokes that the brackets failed were determined and these data were analyzed by statistical analysis using an independent sample t-test and one-way analysis of variance (ANOVA). The level of significance was set at p < 0.05. Generally, differences between the frequency of shearing strokes of the bracket failures were found to be statistically significant depending on the type of adhesives and brackets (p < 0.05). The bonding technique for Group 1 was found to have a significantly higher shear bonding strength than Group 2. It is also seen that different types of bracket belonging to the same or different brands had different shear bonding strength. It may be concluded that: (i) all bracket types used in this study can be applied with both bonding techniques, (ii) in order to minimize the risk of hard tissue damage, ceramic brackets should be carefully bonded using the self-etching primary adhesive technique.

Effect of Different Types of Adhesive Agents on Orthodontic Bracket Shear Bond Strength: A Cyclic Loading Study

“…Universal testing machines, such as Zwicki and Instron, have been used for this purpose [ 29 , 30 ]. There are also differences in the techniques used for debonding, there are various force-application methods, such as wire loops, blades, and metal tips [ 23 , 31 , 32 , 33 ]. The crosshead speed of the testing machine varies between orthodontic bond strength studies.…”

“…When the orthodontic literature is reviewed, it can be seen that the crosshead speeds for bond strength tests generally vary from 0.5 to 5 mm/min [ 34 , 35 , 36 , 37 ]. However, Çiçek et al [ 23 ] examined the shear stroke numbers of brackets using a 300 mm/min crosshead speed in their 2020 study. Klocke et al [ 38 ] showed that the crosshead speed varying between 0.1 and 5 mm/min did not have a significant effect on orthodontic bond strength tests.…”

“…While the teeth were embedded, care was taken to keep the buccal surfaces exposed from the enamel–cementum junction (see Figure 1 ). By fixing the samples, a mechanism was created in the test machine in such a way that the nozzle tip stroked perpendicular to the bracket groove [ 23 ]. There was no acrylic contact with the buccal surface of the teeth.…”