Abstract
Abstract Objectives The aim of the present study was to assess and compare the shear bond strength (SBS) of metal pre-coated orthodontic brackets bonded to fluorotic and non-fluorotic teeth treated with three different etching techniques. A second aim was to determine the volume of adhesive remaining on the tooth at debond using micro-computed tomography (μCT). Methods Ninety extracted premolars were selected to include 45 fluorotic (test group) and 45 non-fluorotic (control group) teeth. Each group was divided into three subgroups of 15 each, which were treated as follows: 1) micro-etched; 2) acid-etched; and 3) both micro-etched and acid-etched. A bonding agent was applied to the prepared surfaces; pre-coated and light-cured brackets were attached to all teeth. An Instron universal testing machine was used to record the debonding force. Specimens were then scanned using a microCT to evaluate the amount of adhesive remaining on the teeth. The significance of the statistical tests was pre-determined at p < 0.05. Results Two-way ANOVA showed that fluorosis of teeth had no influence on the SBS (p = 0.165) whereas the volume of adhesive remnants was significantly higher in the control group compared with the test group (p < 0.001). Conclusions Fluorosis had no influence on the SBS of brackets, whereas it had a negative influence on retaining adhesives onto the tooth surfaces.
Highlights
A consistent adhesive bond between orthodontic brackets and tooth enamel is a requisite for successful treatment,[1] and necessitates careful attention to tooth surface preparation, the design of bracket base and the bonding material.[2]
The bond strength between fluorosed enamel and composite materials has been previously examined[5,6,7,8] but the results indicate that inconsistencies exist
Dental fluorosis was assessed by the same investigator according to the Thylstrup and Fejerskov Fluorosis Index (TFI)[23] and only teeth with moderate to severe fluorosis were included in the test group
Summary
A consistent adhesive bond between orthodontic brackets and tooth enamel is a requisite for successful treatment,[1] and necessitates careful attention to tooth surface preparation, the design of bracket base and the bonding material.[2] Fluorosed enamel has been emphasised as the most challenging enamel surface to which to gain adherence.[3] Brackets bonded to fluorotic teeth may fail due to an inability to effectively etch the hypermineralised and acid-resistant enamel.[4] The bond strength between fluorosed enamel and composite materials has been previously examined[5,6,7,8] but the results indicate that inconsistencies exist. Ng’ang’a et al.[9] found no significant difference in the tensile bond strength of non-fluorotic teeth compared with mild and moderately fluorotic teeth following. The preferred site of bond failure during a debonding procedure is at the resin-bracket interface so that minimal adhesive remains on the tooth surface. Bonding failure at the resin-enamel interface is considered undesirable as the enamel surface may tear during the debonding process.[2] Apart from
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