Restorative procedures in posterior teeth placed during a graduation course clinic: quantitative evaluation about amalgam versus composite resin

A demand increase for aesthetic procedures in Dentistry has been observed due to the crescent interests of patients and the evolution of aesthetic restorative materials. The dental files of patients assisted at the clinic of the graduation course of restorative dentistry, School of Dentistry, University of São Paulo, were analyzed during the period from 1998 to 2003, with the purpose of accomplishing an evaluation of the assisted population as well as a longitudinal comparative study of the percentage of class I and class II restorations with amalgam or composite resin in posterior teeth placed by dental students. In the analyzed period, the amalgam was used in 28.5% of the class I and 27.5% of the class II whereas the composite resin was used in 32.1% of the class I and 11.9% of the class II restorations. Although the class I posterior composite resin restorations had been made in a higher proportion and an increase of these procedures was observed, the class II amalgam restorations were predominant along the analyzed period. The prevalent group was between 31 and 40 years old and female gender. Although there were prevalence of class II amalgam restorations placed, there was an increase of the resin composite restorations in posterior teeth when compared with amalgam restorations, mainly in class I cavity restorations, probably due to its conservative characteristics.

Effects of cleaning agents on bond strength to dentin.

The cleaning of cavity walls aims to improve adhesive restorative procedures and longevity of restorations. This study has compared the effect of three cleaning agents--sodium bicarbonate jet (Profi II, Dabi Atlante, São Paulo, Brazil); pumice paste plus a biologic detergent (Tergestesim, Probem, São Paulo, Brazil); air water spray--on the bond strength between dentin and two different adhesive systems: Clearfil SE Bond (Kuraray, Kioto, Japan) and Scotchbond Multi-Purpose Plus (3M-ESPE, São Paulo, Brazil). Six groups (n: 10) of dental fragments obtained from young adult extracted teeth were prepared, and each one received one of the listed surface cleaning techniques. After the adhesive application, a cone-shaped test body was built with AP-X (Kuraray, Kioto, Japan) or Z100 (3M-ESPE, São Paulo, Brazil) composite resins, using a Teflon matrix. The specimens were tested for tensile bond strength after one-week storage in distilled water at 37 degrees C. Two pairs of fractured specimens of each group were randomly chosen and processed for scanning electron microscopy (SEM) analysis. ANOVA test of the bond strength values showed no statistical differences among the cleaning agents and neither between their interactions with the bonding systems. Upon SEM analysis, most surfaces showed mixed fractures of adhesive and cohesive failures in bonding resin to dentin. Based on statistical and SEM analysis, it was concluded that the cleaning agents studied did not interfere with the bond strength of the adhesive systems used to dentin.

Effects of cleaning agents on bond strength to dentin

A limpeza das paredes cavitárias é um passo importante na clínica odontológica e visa otimizar os procedimentos adesivos e a longevidade das restauracões. O presente estudo comparou o efeito de três agentes de limpeza cavitária - jato abrasivo de bicarbonato de sódio/ar/água (Profi II, Dabi Atlante, São Paulo, Brasil); pasta de pedra-pomes e água, somada a um detergente biológico (Tergestesim, Probem, São Paulo, Brasil); e spray de ar/água - na resistência adesiva entre dentina e dois tipos de adesivos dentais: Clearfil SE Bond ("self-etching") (Kuraray, Kioto, Japão) e Scotchbond Multi-Purpose Plus ("all-etching") (3M-ESPE, São Paulo, Brasil). Seis grupos de espécimes (n = 10) obtidos a partir de elementos dentais humanos extraídos por indicacão foram preparados e cada um recebeu um dos tratamentos de superfície. Após aplicacão dos adesivos, uma porcão tronco-cônica de resina composta (AP-X, Kuraray, Kioto, Japão/Z-100; 3M-ESPE, São Paulo, Brasil) foi construída sobre os espécimes, com o auxílio de uma matriz bipartida de teflon e uma mesa metálica adaptadora para adaptacão na máquina de ensaio de tracão. Após armazenamento em água destilada a 37ºC por 7 dias, os mesmos foram submetidos às provas de tracão. Dois pares de cada grupo foram escolhidos aleatoriamente e processados para observacão ao microscópio eletrônico de varredura (MEV). A análise estatística dos valores obtidos demonstrou que não houve diferencas significantes entre as técnicas de limpeza empregadas e nem entre a interacão destas com os adesivos dentais, e as observacões ao MEV revelaram uma predominância de fraturas mistas ocorridas na interface dentina/resina. Baseados nas análises estatísticas e nas observacões ao MEV, concluiu-se que as técnicas de limpeza empregadas não interferem na resistência adesiva entre a dentina e os sistemas adesivos estudados, nas condicões experimentais adotadas.