ABSTRACT
This study evaluated the influence of various gingival displays on the esthetic perception in the presence of upper dental midline discrepancy. Methods: A smiling image of a male subject was altered digitally to produce five image series: normal smile (series A), decreased tooth show (series B), increased gingival show (series C), maxillary cant (series D), and asymmetric upper lip elevation (series E). In each image series, the midline was deviated to the right and left incrementally. A total of 210 raters (four professional groups and laypersons, n = 42 in each group) determined the midline deviation threshold and the attractiveness of midline position in each series. Results: The right and left thresholds were statistically similar for the symmetrical series (A, B, and C), while for series D, the right threshold was significantly lower. In most rater groups, the mean threshold order was: B > A > E > C > D. In all the series, the raters selected the coincident midline as the most attractive series except for series D, for which 1–2-mm deviations to the left were selected as the most attractive by almost all the groups. Conclusions: It is crucial to establish the coincident midline position in a symmetrical smile, especially when a gummy smile exists. In the asymmetrical gingival show, a coincident midline might not be the most esthetic midline position.
ABSTRACT
Statement of the Problem: Some studies have reported the bond strength to be significantly lower in fluorotic enamels than the non-fluorosed
Purpose: The purpose of this study was to evaluate the shear bond strength of metallic brackets to non-fluorosed and fluorosed teeth after different enamel conditioning
Materials and Method: A total of 176 freshly extracted human premolars [88 nonfluorosed and 88 fluorosed teeth] were used in this study for bonding the metallic brackets. Teeth with moderate fluorosis were used according to Thylstrup and Fejereskov index [TFI]. Eighty non-fluorosed and 80 fluorosed teeth [TFI=4-6] were randomly divided into 8 equal groups of 20 teeth each. The remaining 16 teeth were used for scanning electron microscopy observation. The enamel surface was conditioned by 4 methods: acid etching for 30 sec, acid etching for 120 sec, air abrasion followed by acid etching, and Er: YAG laser etching followed by acid etching. The morphology of etching patterns in different groups was studied under scanning electron microscope
Results: The shear bond strength of fluorosed teeth to the brackets was significantly lower than non-fluorosed ones [p= 0.003]. The shear bond strength of laser-acid groups in both non-fluorosed and fluorosed teeth was significantly lower than other groups [p< 0.001]. Weibull analysis indicated that the chance of failure under the applied force was different between fluorosed and non-fluorosed group. The scanning electron microscope observations revealed that the fluorosed teeth treated with phosphoric acid had fewer irregularities compared to non-fluorosed teeth. The most irregularities were detected in the teeth conditioned with phosphoric acid for 120 seconds
Conclusion: Fluorotic enamel adversely affects the bond strength of orthodontic brackets. None of the conditioning methods tested in this study could significantly improve shear bond strength of metallic brackets. Er: YAG laser conditioning followed by acid further reduced the bond strength in non-fluorosed and fluorosed teeth
ABSTRACT
Orthodontic patients' cooperation is a determining factor in treatment outcomes. The aim of this study was to evaluate the relationship between patient cooperation during orthodontic treatment with variables such as age, sex, life setting, treatment duration and functional and social discomfort experienced. Specimens were consisted of 100 orthodontic patients [36 males and 64 females] between 13-35 years old [average age: 22.57 +/- 1.69 years]. Patients' demographic traits, treatment duration and functional-social discomfort by the orthodontic treatment were evaluated using a questionnaire answered by the patients or their parents. The degree of patient cooperation was assessed by the modified cooperation questionnaire [Orthodontic Patient Cooperation Scale [OPCS] which was completed by an orthodontist. Data were analyzed using One-way ANOVA, T-test, intraclass correlation coefficient and Pearson Correlation. No significant difference was found between the cooperation of male and female patients [P=0.867] and also between the cooperation of the patients who lived in the urban and rural setting [P=0.613]. Treatment duration and compliance showed a low negative correlation which was not statistically significant [r=-0.155, P=0.127]. Functional-social discomfort and compliance showed a low negative correlation which was not statistically significant [r-0.118, P=0.244]. No significant correlations were found between the compliance and age [r=0.002, P=0.988]; and also the treatment duration and functional-social discomfort experienced [r=0.164,P=0.105]. Patient compliance appears to be a complex issue that cannot easily be predicted only by factors such as age, gender, life setting, treatment duration and functional-social discomfort experienced
ABSTRACT
Bolton analysis is a good indicator to evaluate tooth size discrepancies but the ethnic variation of these values should be considered. Thus, the aim of this study was to determine the tooth ratios in different sexes and malocclusion groups in Iranian population and to compare these ratios with the data from the Bolton study. Also the best predictors of anterior and overall Bolton discrepancies were determined in this study. In this cross-sectional study, a total of 715 dental casts [526 female. 189 male] were recruited from department of orthodontics of Shiraz dental school and private offices of orthodontists. The samples were divided into three groups based on Angles Malocclusion groups. Then the greatest mesiodistal widths of all teeth were measured with digital caliper with accuracy of 0.01 mm and the anterior and overall ratios were calculated. Finally, the data were analyzed by Pearson Correlation, independent t-test and Kruskal-Wallis test, through SPSS software. The anterior ratio [78.74%] and the overall ratio [91.94%] showed no statistically significant differences according to sex and malocclusion groups in south Iranian population. The results revealed that the correlation coefficient of lateral ratio with anterior Bolton discrepancy was 0.544 and central ratio with anterior Bolton discrepancy was 0.536. Also the correlation coefficient of first premolar ratio with overall Bolton discrepancy was 0.440 and the second premolar ratio with overall Bolton discrepancy was 0.407. The anterior ratio for the whole population was statistically different from Bolton's, but no statistically significant difference was found for the overall ratio. In Iranian population, the best predictor of anterior Bolton discrepancy was lateral tooth and the best predictor of overall Bolton discrepancy was first premolar