RESUMEN
Objective: Increased enamel surface roughness following orthodontic bracket debonding leads to increased plaque accumulation and enamel decalcification. Therefore, different methods are employed to achieve smoother enamel surfaces after bracket debonding. This study compared enamel surface roughness following orthodontic bracket debonding and composite resin removal using white stone and tungsten carbide burs
Methods: In this in-vitro, experimental study, 20 first and second premolars of 10-20 year-olds were collected and their crowns were mounted in acrylic blocks. Roughness of the buccal surfaces of teeth was determined by atomic force microscopy [AFM] and the brackets were bonded to the teeth. After bracket debonding, composite remnants were removed using white stone and tungsten carbide burs. Parameters of enamel surface roughness were determined by AFM and time required for composite removal was also calculated. Repeated measures ANOVA was used to assess the changes in parameters based on the time of measurement, type of bur and their interaction effect. Time required for composite resin removal by bur was analyzed using one-way ANOVA and Tukey's multiple comparisons
Results: Resin removal increased enamel surface roughness compared to the baseline values in all groups. However, no significant differences were noted between the two types of burs regarding arithmetic average of the roughness profile [Ra], the root mean square roughness [Rq] and the maximum peak-to-valley height in the sampling length [Rt] after resin removal. Time required for resin removal with tungsten carbide bur [34.2 seconds] was significantly shorter than with white stone bur [56.6 seconds][both ps<0.0001]
Conclusion: Considering the similar enamel surface roughness values achieved by the two burs, tungsten carbide burs are recommended for resin removal following orthodontic bracket debonding
RESUMEN
Cleft lip with or without cleft palate [CL/P] is one of the most common congenital anomalies and the etiology of orofacial clefts is multifactorial. Transforming growth factor alpha [TGFA] is expressed at the medial edge epithelium of fusing palatal shelves during craniofacial development. In this study, the association of two important TGFA gene polymorphisms, BamHI [rs11466297] and RsaI [rs3732248], with CL/P was evaluated in an Iranian population. The frequencies of BamHI and RsaI variations were determined in 105 unrelated Iranian subjects with nonsyndromic CL/P and 218 control subjects using PCR and RFLP methods, and the results were compared with healthy controls. A p-value of <0.05 was considered statistically significant. The BamHI AC genotype was significantly higher [p=0.016] in the patients [12.4%] than the control group [5.0%]. The BamHI C allele was significantly higher [p=0.001; OR=3.4, 95% CI: 1.6-7.4] in the cases [8.0%] compared with the control group [2.5%]. Our study showed that there was an association between the TGFA BamHI variation and nonsyndromic CL/P in Iranian population