Effects of a new desensitizing paste containing 8% arginine and calcium carbonate on the shear bond strength of orthodontic brackets / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to evaluate shear bond strength (SBS) and failure site location of brackets bonded to enamel with or without desensitizer application. METHODS: Sixty-six freshly extracted human premolar teeth were randomly divided into 3 groups of 22. Group 1 served as the control. Desensitizer was applied to the remaining teeth at two time intervals (Group 2, bonded immediately after Pro-Relief(TM) (Colgate-Palmolive Co., New York, NY, USA) application and Group 3, bonded 30 days after Pro-Relief(TM) application with the teeth stored in artificial saliva during the 30 days). Orthodontic brackets were bonded with a light cure composite resin and cured with a halogen light. After bonding, the SBS of the brackets was tested using a universal testing device. Adhesive remnant index (ARI) scores were determined after the brackets failed. Data were analyzed with analysis of variance, Tukey's HSD, and G tests. RESULTS: The SBS was significantly lower in Group 2 than in Groups 1 (p = 0.024) and 3 (p = 0.017). Groups 1 and Group 3 did not differ (p = 0.991). ARI scores did not differ significantly among groups. CONCLUSIONS: The Pro-Relief(TM) desensitizer agent applied immediately before bonding significantly reduces bond strength, but the SBS values still exceed the minimum 5.9 - 7.8 MPa required for adequate clinical performance. Immersing the teeth in artificial saliva for 30 days after applying the Pro-Relief(TM) desensitizer agent and before bonding increased the SBS to control levels.

Effects of conventional and modified facemask therapies on dentofacial structures / 대한치과교정학회지

OBJECTIVE: The purpose of this prospective study was to evaluate the dentofacial effects of conventional and modified facemask therapies with rapid maxillary expansion, in a group of Class III patients; and compared with an untreated control group. METHODS: The conventional facemask group (Group 1) comprised of 24 patients, 13 girls and 11 boys (mean age, 9.2 +/- 1.4 years); the modified facemask treatment group (Group 2) comprised of 24 patients, 12 girls and 12 boys (mean age, 9.3 +/- 1.6 years); and the control group (Group 3) comprised of 21 subjects, 11 girls and 10 boys (mean age, 9.8 +/- 1.9 years). Treatment and control changes within the groups and the differences between the groups were analyzed statistically. Intra-group comparisons were evaluated using the non-parametric Wilcoxon's test and intergroup changes were analyzed using the Kruskal-Wallis test. The statistical significance of intergroup differences was further assessed with the Mann-Whitney test for independent samples and applying Bonferroni's correction (p < 0.016). RESULTS: In group 1, SNB changes were less than the control. There were increases in SNA, ANB, SN-MP, A to N perp and Upper lip to E plane. In group 2, SNB, U1-NA (mm) U1-NA (degrees) and Pog to N perp (mm) changes were less than the control. There were increases in SNA, ANB, SN-MP, A to N perp and Upper lip to E plane. CONCLUSIONS: Modified facemask appliance can be used effectively in Class III patients with a retrognathic maxilla. Facemask therapies with expansion resulted in an anterior advancement and translation of maxilla without rotation; and the mandible moved downward and backward in both treatment groups.