José Fortunato Ferreira Santos

Morphological characterization of the tooth/adhesive interface

The purpose of this study was to assess the morphological characteristics of the tooth/adhesive interface using different adhesive systems in MOD restorations under scanning electron microscopy (SEM). The tested hypothesis was that the morphology of the bonding interface would vary in different areas of MOD restorations for the three adhesive systems. MOD cavities were prepared in 12 sound extracted human third molars and restored with Filtek Z250 composite resin and one of the following adhesive systems: Experimental ABF (n=4), Clearfil SE Bond (n=4) self-etching primers and Single Bond etch-and-rinse adhesive system (n=4). After 24-h storage in distilled water at 37 degrees C, teeth were sectioned and prepared for SEM. The interfacial morphology varied depending on the adhesive system and also on the evaluated area. The null hypothesis was accepted because the morphology of the tooth/adhesive interface reflected the characteristics of both the dental substrate and the adhesive systems.

Clinical behavior of repaired amalgam restorations: A two-year study

Replacement of amalgam restorations may lead to more destruction of sound dental tissue, is often a time-consuming chair procedure, and it does not always provide a favorable risk/benefit balance for the patient. This article reviews the clinical alternative of repairing instead of completely replacing old amalgam restorations. During a 2-year period, 45 repaired restorations were monitored every 6 months by direct (clinical) and indirect (color slides and stone casts) methods. Findings of this study reveal broad clinical success when based on proper indications.

Punch shear strength of polycarboxylate cements

Two general conclusions are drawn which apply to all the four commercial polycarboxylate cements: First, the effect of storage condition upon shear strength was much more pronounced after 24 hours than after 1 hour of storage time; second, the effect of storage condition was most extreme when the specimens were tested free of their matrices. Additionally some specific comparisons between the four products tested can be made based on differences of shear strength within the same experimental condition. The effect of confinement decreased in the following order: Boston greater than Bondal greater than PCA greater than Durelon. Sensitivity to storage conditions decreased in this order: Durelon greater than Bondal greater than PCA greater than Boston. Finally sensitivity to storage times decreased in the order Bondal greater than Durelon greater than Boston greater than PCA.

Studies on Microstructure of Gold Soldered Joints

Solder microstructures were found to be influenced by those of the castings. A tendency of solder to match the microstructures contacted during its solidification was demonstrated. Several different types of defects were identified in the soldered joints. Tentative correlations of the observed microstructures and defects with physical properties, corrosion resistance and dimensional changes of soldered structures have been made.

Avaliação in vitro da microinfiltração na interface selante/esmalte sob a influência de contaminação, emprego de "primer" e tipo de selante

This in vitro study investigated the effect of different types of sealants (Concise Light Cured White Sealant - 3M; Fluroshield - Caulk/Dentsply) and the use of primer (Tenure - Den-Mat) on the microleakage of saliva-contaminated enamel. Sealants were placed on 360 surfaces (occlusal, buccal and lingual) of extracted teeth free of caries. After being prepared according to each experimental group, they were thermocycled (5 and 55oC) for 500 and 2.000 cycles. Then they were immersed in a silver nitrate solution (50%) and cut in longitudinal slices. The results were described in linear measurements (mm) by means of a digital-image analysis system. Contamination and use of primer had different influences when subjected to the different experimental conditions. Both sealants had the same influence on microleakage. Flow of Fluroshield into pit and fissures was improved by use of the primer, and a greater amount of bubbles could be observed in this material.

Delayed hygroscopic expansion of phosphate-bonded investments

Abstract Delayed hygroscopic expansion is caused by immersion of investments after their nominal final set. Its magnitude was established in a previous paper (1) for gypsum bonded investments. In the present investigation high values of delayed hygroscopic expansion were also found for phosphate-bonded investments. In addition, experimental conditions intentionally introduced (liquid concentrations for spatulation and immersion times) caused significant differences upon the measured values of expansion. Such variations if not adequately controlled by the dental laboratory technician can cause severe casting misfits.