ABSTRACT
OBJECTIVE: The aim of this in vitro study was to evaluate the microtensile bond strength (µTBS) to dentin of two different restorative systems: silorane-based (P90), and methacrylate-based (P60), using two cavity models. MATERIAL AND METHODS: Occlusal enamel of 40 human third molars was removed to expose flat dentin surface. Class I cavities with 4 mm mesial-distal width, 3 mm buccal-lingual width and 3 mm depth (C-factor=4.5) were prepared in 20 teeth, which were divided into two groups (n=10) restored with P60 and P90, bulk-filled after dentin treatment according to manufacturer's instructions. Flat buccal dentin surfaces were prepared in the 20 remaining teeth (C-factor=0.2) and restored with resin blocks measuring 4x3x3 mm using the two restorative systems (n=10). The teeth were sectioned into samples with area between 0.85 and 1.25 mm2 that were submitted to µTBS testing, using a universal testing machine (EMIC) at speed of 0.5 mm/min. Fractured specimens were analyzed under stereomicroscope and categorized according to fracture pattern. Data were analyzed using ANOVA and Tukey Kramer tests. RESULTS: For flat surfaces, P60 obtained higher bond strength values compared with P90. However, for Class I cavities, P60 showed significant reduction in bond strength (p<0.05). No statistical difference between restorative systems was shown for Class I cavity model (p>0.05), or between Class I Cavity and Flat Surface group, considering P90 restorative system (p>0.05). Regarding fracture pattern, there was no statistical difference among groups (p=0.0713) and 56.3% of the fractures were adhesive. CONCLUSION: It was concluded that methacrylate-based composite µTBS was influenced by cavity models, and the use of silorane-based composite led to similar bond strength values compared to the methacrylate-based composite in cavities with high C-factor. .
Subject(s)
Humans , Dental Bonding/methods , Dentin/drug effects , Methacrylates/chemistry , Silorane Resins/chemistry , Tensile Strength , Analysis of Variance , Models, Dental , Dental Restoration, Permanent/methods , Dental Stress Analysis , Materials Testing , Surface Properties/drug effects , Time Factors , Tooth FracturesABSTRACT
Sabendo-se que a sacarose desempenha papel fundamental no surgimento de lesöes cariosas, é objetivo do presente trabalho verificar sua real influência, relacionada principalmente a duas variáveis: freqüência de ingestäo e consistência dos alimentos que contêm esse carboidrato. Para tanto, foram analisadas cinqüenta fichas clínicas de pacientes da Clínica de Odontopediatria da Faculdade de Odontologia da Universidade Federal de Minas Gerais (FO-UFMG), na faixa etária de cinco a sete anos, escolhidas aleatoriamente. Comparando-se os diários dietéticos com os índices de cárie, pôde-se observar que quanto maior o consumo diário de sacarose, maior a prevalência de lesöes cariosas. A maioria absoluta das crianças apresentou consumo excessivo de sacarose associado a altos índices de cárie, o que revela grande necessidade do aconselhamento dietético por parte do profissional, contando com a colaboraçäo dos pais