Biomedical subjects

A Senda

Publications and source records attributed to A Senda.

15 recordsLinked to original sources

PubMed1990

The effect of various treatments on composite materials in bonding with resin cements.

The present study investigated the influence of surface treatments of composite materials using 6% hydrofluoric acid or 2% acidulated phosphate fluoride, the influence of the application of a bonding agent to the surface, and the influence of incremental curing of composite materials on the shear bonding strength between composite materials and resin cements. These results were studied statistically by analyzing variances in three-way classification and by their contributory ratios. The effects of hydrofluoric acids or acidulated phosphate fluorides on the treated surfaces of composite materials, and also the interfaces between composite materials and resin cements were further examined by mean of scanning electron microscopy (SEM). Unlike the controls, surfaces of all specimens treated with hydrofluoric acid or fluoride revealed micro-porous surfaces, but the effect of the surface treatment on the bonding strength was not equal for all the composite materials tested. The application of a bonding agent influenced some composite material, but the incremental curing of composite materials had no influence on bonding with resin cements.

Acidulated Phosphate Fluoride↗

PubMed1990

[Study on porcelain veneer restorations. 2. Influence of hydrofluoric acid on bonding strength at the porcelain-resin interface].

Recently, porcelain veneer restoratives have been introduced to the general practice, and their clinical performances have been confirmed through many longterm clinical investigations. It is expected that porcelain veneer restorations will perform successfully in esthetic, conservative and abhesive dentistry. It is an well known fact that the micro-mechanical bonding strength at the porcelain-resin interface which is achieved through the application of hydrofluoric acid to the porcelain surface is quite a strong bonding mechanism. However, there are very few studies reporting on the acid treatment of porcelain surfaces. The authors have been studying the influence of hydrofluoric acid on porcelain surfaces, and in our previous report we reported, the degrees of corroded porcelain treated with different concentrations of hydrofluoric acid for different durations of application. In the present study, shear bonding strength was measured between resin cements and porcelain surfaces treated with different concentrations (4, 6, 8%) of hydrofluoric acid and for different durations (1 to 24 min.), and the appropriate treatment of porcelain surfaces with regard to the bonding strength was determined. The results obtained were as follows. 1. As the treating time increased with any concentration (4, 6, 8%) of hydrofluoric acid, corrosion of the porcelain surface became more intense. Hardly any evidence of corrosion was observed on any porcelain surface treated for one minute, so it seems that the treatment of porcelain surfaces using 4 to 8% hydrofluoric acids should be continued for over three minutes. 2. Observation of the surface profile by SEM showed no significant differences between the surfaces treated for 3, 6, 12 and 24 minutes. 3. It was not clear as to how the differences of hydrofluoric acid concentrations (4, 6, 8%) plus the differences in the kinds of porcelain (Super Porcelain AAA, NORITAKE Co. Ltd., VMK 68, Vita Zahnfabrik Gmbh & Co., Cosmotech Porcelain, G-C Co. Ltd.) had affected the differences in the amount of corrosion. 4. Regarding to the shear bonding strength at the porcelain-resin cement interface, in comparison with control specimens which were only sandblasted, about all two to three times higher bonding strength were obtained in specimens treated with any concentration (4, 6, 8%) of hydrofluoric acids and for any duration between 3 to 24 minutes. Specimens treated for one minute were an exception.

Composite Resins↗

PubMed1990

[Study on the porcelain veneer restoration. 3. Effect of various treatments of porcelain surface on the bonding strength at porcelain-resin interface].

In a previous report, observations were made on the apporopriate concentrations of hydrofluoric acid and durations of application in treating porcelain surfaces to improve the bonding strength at the porcelain-resin interface. Particular concentrations and durations were found, such as 4%, 6 min. for Supper Porcelain AAA, 8%, 6 min. for VMK 68, and 6%, 3 min. for Cosmotech Porcelain, and it was clearly shown that hydrofluoric acid treatment was the most effective treatment for porcelain-resin micro-mechanical bonding. However, because of its strong corrosive action, the use of hydrofluoric acid is very dangerous, and it must be handled with extreme care even in the laboratory. Accordingly, there is a need to find a safer and more effective way of treating porcelain surfaces, particularly in the field of interoral repairs to fractured porcelain restoratives by means of porcelain-resin micro-mechanical bonding. In the present study, 2% acidulated phosphate fluoride (APF), which corrodes the surface of porcelain restoratives, PorceLock (PL), which is a 2.5% buffered hydrofluoric acid made by DenMat Co. and a 6% hydrofluoric acid (HF) preparations were applied to the surface of porcelain specimens and the resulting effects on treated porcelain surfaces were examined by means of SEM observations and shear bonding strength tests. The following results were obtained: 1. In comparison with control specimens which were not treated with any acids or fluoride, a much higher bonding strength at the porcelain-resin interface was obtained in the specimens treated with 2% APF, PL and 6% HF. 2. Regarding to SEM observations, both of the specimens treated 6% HF or PL showed extremely micro-porous surfaces.2+ surfaces of the

Acidulated Phosphate Fluoride↗

PubMed1988