The effect of cigarette smoke on the shear bond strength of metallic and ceramic orthodontic brackets: An in vitro study

Abstract

The bond strength between enamel and the bracket base is influenced by exposure to the oral environment. The aim of the current study was to determine the effect of cigarette smoke on the shear bond strength (SBS) of bonded metallic and ceramic orthodontic brackets. a sample of 60 sound extracted premolars were divided into four groups (n=15 each) as follows: group (A): ceramic brackets without smoke exposure, (B): metallic brackets without smoke exposure, (C): ceramic brackets with smoke exposure, (D): metallic brackets with smoke exposure. Smoking exposure was simulated using the British American Tobacco's exposure chamber manufactured by Curbridge Engineering (Hampshire, UK). Metallic and ceramic brackets were bonded to the enamel using conventional acid etching technique. SBS (MPa) was tested using the universal Instron testing machine at a constant cross head speed of 1mm/min until failure. Kolmogorov-Smirnov test was used to test the normality of the measurements. One-way analysis of variance (ANOVA) was used to compare the means of SBSs between the four groups, Post-hoc with least significance difference was used to perform a pairwise comparison between means. Statistical significance was set at P<0.05. The highest SBS corresponded to the ceramic type brackets bonded to a non-smoking sample (15.7±9.5) while the lowest levels of SBS was related to metallic type brackets bonded to smoke exposed sample (2.8±0.7) and the difference was statistically significant (P<0.05). Cigarette smoke consumption has significant effects on the SBS of orthodontic brackets. SBS levels were significantly lower in the smoke exposure groups and the lowest values corresponded to the cigarette smoke exposed metallic brackets.