Chitosan improves the durability of resin-dentin interface with etch-and-rinse or self-etch adhesive systems

Degradation of the dentin-resin interface can occur due to hydrolysis of exposed collagen, resulting in reduced bond strength. This study assessed the effect of dentin treatment with chitosan combined with an etch-and-rinse or self-etch adhesive system on improvement of bond strength and preservation of the interface durability. Methodology: Enamel was removed from 80 molars and the teeth were divided into two groups: without chitosan (control) or with 2.5% chitosan gel (1 min). They were further subdivided into two subgroups according to the adhesive system: etch-and-rinse or self-etch. Dentin was restored using a composite resin. Half of the specimens from each restored group were subjected to interface aging and the remaining specimens were used for immediate analysis. The specimens were sectioned and subjected to microtensile bond strength (µTBS) test (n=10), chemical composition testing using Fourier-transform infrared (FTIR) spectroscopy (n=4) and energy-dispersive spectroscopy (EDS) (n=5), and morphological analysis of the adhesive interface using scanning electron microscopy (SEM) (n=5). Data were analyzed using three-way ANOVA. Results: Chitosan improved the µTBS of the adhesive interface when compared with the control group (p=0.004). No significant differences were observed in dentin adhesion between the adhesive systems (p=0.652). Immediate µTBS was not significantly different from that after 6 months (p=0.274). EDS and SEM did not show significant differences in the chemical and structural composition of the specimens. FTIR showed a decrease in the intensity of phosphate and carbonate bands after using chitosan. Conclusions: Dentin treatment with chitosan combined with an etch-and-rinse or self-etch adhesive system improved the immediate and preserved the 6-month bond strength of the adhesive interface

Reproducibility of skeletal and dental maturation parameters

ABSTRACT Objective: Amongst other factors, the effectiveness of orthodontic treatment in children and adolescents depends on the identification of most appropriate intervention timing, which has been traditionally based on the identification of maturational stages. There is a wide variety of radiographic methods to identify these phases, either through skeletal parameters, or dental calcification. Considering that the reliability of any given assessment tool is required to enable its safe clinical use, and aiming an appropriate implementation of these parameters in future researches, this study was performed to assess the reproducibility of radiographic growth evaluation methods. Methods: Lateral teleradiographs, hand-wrist, and panoramic radiographs of sixty-eight orthodontic patients randomly selected from files of the Orthodontics Graduation Course (Guarulhos University, Guarulhos, SP, Brazil) were evaluated by two examiners to access both intra- and inter-examiner reproducibility of the assessment methods conceived by Baccetti et al.; Fishman; Greulich and Pyle; Nolla and Demirjian et al. Results: All methods analyzed showed satisfactory intra- and inter-examiner reliability. Among those that evaluated skeletal maturity, a relatively better performance was observed for Baccetti’s method. Fishman’s and Greulich’s parameters presented similar rates, as did Nolla’s and Demirjian’s. Conclusion: The assessment tools analyzed presented adequate reproducibility and might potentially be used as assessment tools to evaluate children and adolescent’s craniofacial growth. Further researches could evaluate the accuracy of radiographic dental calcification parameters for the identification of craniofacial growth stages