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

OBJECTIVE: 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. MATERIALS AND METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Dental arch dimensions, form and tooth size ratio among a Saudi sample.

OBJECTIVES: To determine the dental arch dimensions and arch forms in a sample of Saudi orthodontic patients, to investigate the prevalence of Bolton anterior and overall tooth size discrepancies, and to compare the effect of gender on the measured parameters. Methods: This study is a biometric analysis of dental casts of 149 young adults recruited from different orthodontic centers in Jeddah, Saudi Arabia. The dental arch dimensions were measured. The measured parameters were arch length, arch width, Bolton's ratio, and arch form. The data were analyzed using IBM SPSS software version 22.0 (IBM Corporation, New York, USA); this cross-sectional study was conducted between April 2015 and May 2016. Results: Dental arch measurements, including inter-canine and inter-molar distance, were found to be significantly greater in males than females (p less than 0.05). The most prevalent dental arch forms were narrow tapered (50.3%) and narrow ovoid (34.2%), respectively. The prevalence of tooth size discrepancy in all cases was 43.6% for anterior ratio and 24.8% for overall ratio. The mean Bolton's anterior ratio in all malocclusion classes was 79.81%, whereas the mean Bolton's overall ratio was 92.21%. There was no significant difference between males and females regarding Bolton's ratio. Conclusion: The most prevalent arch form was narrow tapered, followed by narrow ovoid. Males generally had larger dental arch measurements than females, and the prevalence of tooth size discrepancy was more in Bolton's anterior teeth ratio than in overall ratio.