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Biomedical subjects

A Della Bona

Publications and source records attributed to A Della Bona.

7 recordsLinked to original sources
PubMed1998

Ceramic surface preparations for resin bonding.

PURPOSE: To evaluate the effects of hydrofluoric acid (HF) and acidulated phosphate fluoride (APF) primers on differently prepared leucite-containing feldspar ceramic surfaces. MATERIALS AND METHODS: Discs of a leucite-containing feldspar ceramic were prepared following the manufacturer's instructions. Surfaces were either polished, grit blasted or prepared with a diamond bur and then subjected to a range of etching procedures using HF or APF. The surface topography was examined using scanning electron microscopy (SEM). Back-scattered imaging, EDS and X-ray diffraction (XRD) were used for microstructural and compositional analysis. RESULTS: The etching process with HF consisted of a preferential attack of the leucite phase relative to the glass but also removed all features of the previous surface preparation. In contrast, APF etching resulted in the formation of surface deposits, superimposed on the surface roughness created by the prior surface preparations. It was not possible to identify the deposits after APF etching using XRD.

Acid Etching, Dental↗
PubMed1998

The effect of amalgam bonding on resistance form of Class II amalgam restorations.

OBJECTIVE: This study evaluated the load required to produce failure in Class II bonded amalgam restorations. METHOD AND MATERIALS: Five groups of 12 maxillary molars were mounted. Class II mesio-occlusal preparations were cut: group 1, extension through central grooves, without retention grooves; group 2, proximal slot preparation, without retention grooves; groups 3 and 5, slot preparation with long facial and lingual retention grooves; group 4, slot preparation without grooves, with unsupported proximal enamel allowed to remain. Groups 1 to 4 were restored with an amalgam-bonding system and amalgam; in group 5, no amalgam-bonding material was used. RESULTS: Mean (SD) failure loads: group 1, 281 (77) N; group 2, 246 (101) N; group 3, 238 (84) N; group 4, 254 (100) N; and group 5, 191 (66) N. CONCLUSION: Although there was a trend toward greater resistance to dislodgment or fracture when an amalgam-bonding technique was used, its use did not significantly increase the resistance to failure when compared to retention grooves alone.

Analysis of Variance↗
PubMed1995

Shear vs. tensile bond strength of resin composite bonded to ceramic.

Since the mode of failure of resin composites bonded to ceramics has frequently been reported to be cohesive fracture of either ceramic or resin composite rather than separation at the adhesive interface, this study was designed to question the validity of shear bond strength tests. The reasons for such a failure mode are identified and an alternative tensile bond strength test evaluated. Three configurations (A, conventional; B, reversed; and C, all composite) of the cylinder-on-disc design were produced for shear bond strength testing. Two-dimensional finite element stress analysis (FEA) was carried out to determine qualitatively the stress distribution for the three configurations. A tensile bond strength test was designed and used to evaluate two ceramic repair systems, one using hydrofluoric acid (HF) and the other acidulated phosphate fluoride (APF). Results from the shear bond strength tests and FEA showed that this particular test has as its inherent feature the measurement of the strength of the base material rather than the strength of the adhesive interface. In the tensile test, failure invariably occurred in the adhesive layer, with HF and APF showing a similar ability to improve the bond of resin composite to ceramic. It is concluded that the tensile bond strength test is more appropriate for evaluating the adhesive capabilities of resin composites to ceramics.

Acidulated Phosphate Fluoride↗
PubMed1994

Shear bond strength of resin bonded ceramic after different try-in procedures.

Final cementation of porcelain laminate veneers may require a previous colour match try-in. The purpose of this in vitro study was to evaluate the effect on shear bond strength of resin bonded to porcelain after the application of different try-in procedures. Forty porcelain specimens were fabricated, flattened with 600 grit SiC, etched with hydrofluoric acid and silane treated. After 24 h the specimens were divided into four groups at random and prior to bonding of a dual cure resin composite button were treated as follows: Group 1, no treatment (control); Group 2, non-activated resin applied for 5 min, cleaned in acetone for 3 min; Group 3, as for Group 2, with silane reapplied; Group 4, as for group 3, but re-etched for 30 s before reapplication of silane. After bonding the specimens were stored in water at room temperature for 7 days. Shear bond strength data were as follows: Group 1, 18.6 +/- 1.6; Group 2, 15.9 +/- 1.7; Group 3, 16.7 +/- 2.6; Group 4, 15.3 +/- 3.0 MPa. Fractured surfaces examined, under light microscopy and scanning electron microscopy (SEM), showed cohesive failure within the porcelain in all cases. The reduction in mean bond strength after application of a try-in resin was significant in Groups 2 and 4 compared with the control (ANOVA P < 0.05). No other significant differences were measured. In conclusion a single reapplication of silane maintained the bond strength of resin to porcelain when final cementation was preceded by a try-in procedure and cleaning.

Acetone↗
PubMed1994

The strength of Class II composite resin restorations as affected by preparation design.

This study evaluated the load, applied to the marginal ridge, required to produce failure in Class II posterior composite resin restorations with four different preparation designs. In group 1, the preparation had an extension through the occlusal groove. The other three groups employed a proximal box-only (slot) preparation. Group 2 preparations had facial and lingual retention grooves that extended from the gingival floor to the occlusal surface; group 3 preparations were slots without grooves; and group 4 preparations were slots without grooves and with unsupported proximal enamel. After the restorations were thermocycled, their marginal ridges were flattened and loaded to failure. Mean (SD) failure loads were 438 (73) N in group 1; 383 (52) N in group 2; 297 (72) N in group 3; and 281 (63) N in group 4. Mean failure loads of groups 1 and 2 were not significantly different from each other but were significantly greater than failure loads for groups 3 and 4. Mean failure loads of groups 3 and 4 were not significantly different.

Analysis of Variance↗