RESUMO
Background. Bracket base design is a factor influencing shear bond strength. High shear bond strength leads to enamel crack formation during debonding. The aim of this study was to compare enamel damage variations, including the number and length of enamel cracks after debonding of two different base designs. Methods. Eighty-eight extracted human premolars were randomly divided into2 groups (n=44). The teeth in each group were bonded by two types of brackets with different base designs: 80-gauge mesh design versus anchor pylon design with pylons for adhesive retention. The number and length of enamel cracks before bonding and after debonding were evaluated under an optical stereomicroscope ×40 in both groups. Mann-Whitney U test was used to compare the number of cracks between the two groups. ANCOVA was used for comparison of crack lengths after and before debonding in each group and between the two groups. Results. There was a significant increase in enamel crack length and numbers in each group after debonding. There was no significant difference in enamel crack numbers after debonding between the two groups, whereas the length of enamel cracks was significantly greater in anchor pylon base design after debonding. Conclusion. Bracket bases with pylon design for adhesive retention caused more iatrogenic debonding damage to enamel surface.
RESUMO
AIM: This study is aimed at investigating the prevalence of disorders among patients referred to Tabriz Dental School in 2016. MATERIALS AND METHODS: This research was conducted in a cross-section method and taken from all patients admitted during this period. Classification of dental occlusion in patients was based on Angle's definition, skeletal classification was based on Steiner's analysis, and overjet and overbite values and other patient-related information were imported from the records in the extractive sector and in specific forms. After reviewing the data, the forms of individual patients were inputted into the computer and analyzed. RESULTS: In terms of dental condition, the prevalence of malocclusion CL.I, malocclusion CL.II, and malocclusion CL.III was respectively, 50, 36.8, and 13.2%. In terms of overjet condition, 13.9% of patients had normal overjet, 67.1% had increased overjet, 8.9% had reduced overjet, and 10.1% had reversed overjet. In terms of overbite, 17.7% of patients had normal overbite, 53.2% had increased overbite, 8.9% had decreased overbite, 15.2% had open bite, and 5.1% had deep bite. Skeletally, 24.1% of patients had skeletal abnormalities CL.I, 62% had skeletal deformities CL.II, and 13.9% had skeletal CL.III. CONCLUSION: The most common dental malocclusion among patients was related to CL.I and the most common skeletal malocclusion was related to CL.II, and malocclusions of CL.III had the least prevalence both dentally and skeletally. There was no significant relationship between dental and skeletal malocclusions and also between different malocclusions and gender. CLINICAL SIGNIFICANCE: Knowledge of the prevalence of different types of dental and jaw anomalies is considered as the first step in the evaluation and treatment of these disorders. It is worth mentioning that the results of the study can be used in treatment planning required in the province and even in the country.
