Dionísio Vinha

Surface roughness of a dental ceramic after polishing with different vehicles and diamond pastes

During fabrication of bonded ceramic restorations, cervical adaptation, occlusal adjustment and final finishing/polishing are procedures to be performed at the dental office after adhesive cementation. Final adjustments may result in loss of ceramic glaze, which requires new polishing of the ceramic surface, with special attention for selection of adequate materials and instruments. The purpose of this study was to evaluate the efficiency of different vehicles associated with diamond pastes indicated for dental ceramic polishing. Two polishing pastes (Crystar Paste and Diamond Excell) associated with four vehicles (rubber cup, Robinson bristle brush, felt wheel and buff disc) were evaluated. Disc-shaped specimens were fabricated from Ceramco II dental ceramic. Surface roughness means (Ra) of the ceramic specimens were determined with a rugosimeter. Data were analyzed statistically by two-way ANOVA and Tukeys test at 5% significance level. There was no statistically significant difference (p>0.01) between the polishing pastes. However, there were statistically significant differences (p<0.01) among the tested vehicles. Vehicle-paste interaction showed statistically significant difference (p<0.05) as well. It may be concluded that: 1) Robinson bristle brush, felt wheel and buff disc were efficient vehicles to be used in association with a diamond polishing paste; 2) The use of rubber cup as a vehicle showed poor efficiency for mechanical polishing of the ceramic surfaces; 3) Both pastes provided similar and efficient polishing and may be recommended for use with an appropriated vehicle.

Comparison of different methods for the occlusal dentine caries diagnosis

The aim of this study was to compare the effectiveness of in-vitro methods for the occlusal dentine caries diagnosis. Thirty-eight sites were evaluated on third molars without macroscopic carious cavitation in adult individuals from the city of Barretos (SP), Brazil. Visual inspection (VI), endoscopic evaluation (AcuCam), visual inspection and blunt-tipped exploratory probes (Tactile), conventional bite-wing radiographs (CR), direct bite-wing digital radiograph (DR), and direct digital radiograph with contrast and brightness controled (DRbc) were used by five observers. In order to validate the data, the teeth were sectioned and histologically evaluated. The average sensitivity and specificity values of the methods were respectively:0,25 , 0,96 (VI); 0,15 , 0,92 (AcuCam); 0,17 , 0,95 (Tactile); 0,45 , 0,73 (CR); 0,33 , 0,80 (DR) and 0,35 , 0,84 (DRbc) , the effectiveness of clinical methods (VI, AcuCam and Tactile) as well as that of radiographic methods (CR, DR and DRbc) were comparatively similar. The clinical methods presented a smaller number of false-positive diagnosis than the radiographic methods. It was concluded that visual inspection is an important diagnostic method; conventional bite-wing and digital radiography aid the diagnosis and are equally efficient to diagnose carious lesions in the dentine of teeth without visible cavitation.

Dental enamel: qualitative evaluation of the surface after application of aluminum oxide (microetching) using the scanning electron microscope

Dentistry nowadays can count on a wide range of resources to treat patients. With the development of adhesive materials and several newly introduced restorative techniques, the dental structure can be subjected to different sorts of surface treatment. The use of aluminum oxide flow at high speed to remove dental structure was described by Black in 1945, however, the literature regarding the use of aluminum oxide jet is still scarce, as far as the alterations occurring in the dental structure are concerned. At the present, with the development of new abrasive air equipment, microabrasion has been added to several adhesive restorative techniques, in the preparation of the dental surface and of inner surfaces of indirect restorations, which will receive the application of adhesive materials. The aim of this study was to assess the alterations produced by abrasive air applied on the dental enamel by means of electronic microscopy, taking into consideration micromorphological surface alterations. The importance of this study is based on the fact that alternative surface treatments both chemical and mechanical could be introduced in surface priming, including dental enamel priming.

Alterações nas propriedades físicas do amálgama dental por perda de mercúrio durante a trituração mecânica

The purpose of this study was to evaluate quantitatively and comparatively, the occurrence of mercury leakage during the mechanical trituration of amalgam from capsules available in the domestic marketplace, and the possible effects of this leakage on the physical properties of the material. Analyzed items were compressive strength, dimensional change, and static creep.