Shear bond strength of metal brackets to ceramic surfaces using a universal bonding resin

Assure Plus is a recently introduced universal adhesive with the ability to bond to various restorations. This study compared the shear bond strength of brackets bonded to two types of ceramics using conventional bonding agent and Assure Plus. Surface damage caused by debonding was also evaluated. In this in vitro study, 40 feldspathic and lithium disilicate ceramic discs were sandblasted, etched with 9.6% hydrofluoric acid and divided into two groups. In group 1, silane was applied and air-dried followed by application of Transbond XT primer, which was light-cured. In group 2, Assure Plus was applied and air-dried. In both groups, maxillary central incisor brackets were bonded. After incubation in distilled water at 37°C for 24 hours and 2000 thermal cycles, bond strength was measured using a universal testing machine, and the adhesive remnant index (ARI) and failure modes were determined. ANOVA and LSD tests were used to compare bond strength values; chi-squared test was used to compare ARI scores. Bracket bond to lithium disilicate by Assure Plus was significantly stronger than that to Feldspathic porcelain (P=0.041). Only in the Assure Plus/lithium disilicate group did some adhesive remain on the surface following debonding (40% of samples, P<0.05). Cohesive porcelain fracture had the lowest frequency in the lithium disilicate/Assure Plus group. Assure Plus provided high bond strength between ceramic and brackets and minimized damage to lithium disilicate ceramic during debonding. Assure Plus is recommended for use in orthodontic treatment of adults with ceramic restorations

Correlation of dental age estimated by Moorrees and Demirjian methods with chronological age in orthodontic patients

Background: Dental age determination has been considered for malocclusion treatment planning by Orthodontists and Pediatric Dentists. Objective: The aim of this study was to compare the correlation of dental age estimated by Demirjian and Moorrees methods with chronological age in the orthodontic patients. Methods: In this analytical study, 419 panoramic images of 6-15 years old orthodontic patients referred to School of Dentistry in Qazvin were assessed in 2013. Dental age was estimated by Moorrees et al. (1963) and Demirjian et al. (1973) methods through the calcification stages of the left mandibular teeth with the exception of the third molar. Data were analyzed using paired T-test and Pearson’s correlation coefficient. Findings: Of 419 patients, 190 (45%) were male and 229 (55%) were female. The mean age was 11.26±2.47. Although there were positive significant correlations between the methods in all study subjects, the Moorrees dental age was significantly different from the chronological age in all age groups. The Demirjian dental age was significantly different from chronological age in the 6-year old age group and 7, 12 and 15-year old males. There were significant differences between the Moorrees and Demirjian dental age in all age groups. Conclusion: With regards to the results, it seems that the Moorrees method is not appropriate for Iranian population while the Demirjian method can be acceptable for estimation of dental age based on chronological age. Due to the overestimation found in the Demirjian method, exclusive tables must be prepared for Iranian population. Keywords: Age Determination by Teeth, Moorrees Method, Demirjian’s Metho