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Biomedical subjects

A D Wilder

Publications and source records attributed to A D Wilder.

31 records · Page 2Linked to original sources
PubMed1989

Comparison of direct and indirect methods for analyzing wear of posterior composite restorations.

The vast majority of recent clinical research involving wear analyses of posterior composite resin restorations have used either the direct evaluation method (USPHS) or the indirect cast comparison (Leinfelder) method. However, there has never been any established correlation of the two wear scales. The objective of this study was to determine the amount of wear for the USPHS alfa-bravo transition on the basis of cast comparison data. Clinical wear data were collected over five years by both the direct method and the indirect method. Three materials were used involving a total of 221 restorations in 61 patients. Each restoration was evaluated at baseline, six months, one, two, three, and five years by each method. Then, for those restorations which underwent a transition from an alfa to a bravo clinical rating, the absolute wear at the transition was determined by averaging the indirect ratings just before and just after the transition. The mean wear corresponding to the alfa-bravo transition was 192 +/- 60 microns. Because of the large width of the alfa category up to the alfa-bravo transition, extensive early changes and high initial wear rates cannot be detected by the USPHS system.

Bicuspid↗
PubMed1989

Three-year clinical evaluation of a self-cured posterior composite resin.

A study was conducted to determine whether the wear resistance of a posterior composite could be improved by maximizing filler particle-to-particle contacts. This was expected to reduce stress concentrations on the resin matrix and thus reduce occlusal wear. A self-curing quartz-filled composite with this design, P-10, was used to restore 90 Class I and II cavity preparations in adult teeth. Restorations were recalled after baseline at six months, one year, two years, and three years to measure wear by direct and indirect evaluation methods. There was no apparent advantage for this material compared with other previously evaluated posterior composites. The average cumulative wear for P-10 after three years was 145 microns. In addition, the restorations were evaluated for color-matching, interfacial staining, secondary caries, marginal adaptation, surface texture, and postoperative sensitivity. This material was not significantly different in those ways from other posterior composite products except in terms of more rapid color change, because it is self-cured.

Bicuspid↗
PubMed1988

Twelve-month clinical study of dentinal adhesives in class V cervical lesions.

Recently, numerous resin systems claiming dentinal adhesive properties have been introduced. This study evaluated the clinical performance of two such adhesive resins in seven various material and technique combinations without conventional cavity-retention features. To identify potential risk factors in regard to retention, nonmaterial- and technique-related variables such as patient age and occlusion were also evaluated.

Adhesives↗
PubMed1986

Wear rates of posterior composite resins.

The wear rates of nine posterior composite resins were determined for a period of up to 3 years. The wear rates observed depended on the method used for evaluation. A quantitative method of evaluation showed that the wear rates decreased with time. With the use of the quantitative measurements obtained at the end of 6 months after insertion, it was possible to predict the average annual rates of wear at the end of 3 years.

Bicuspid↗
PubMed1983

Three-year clinical study of UV-cured composite resins in posterior teeth.

Four proprietary composite resins cured with ultraviolet light were inserted into Class I and II cavity preparations. The restorations were evaluated over a 3-year period for color match, interfacial staining, secondary caries, loss of anatomic form, marginal adaptation, and surface texture. The percent of restorations exhibiting no generalized loss of anatomic form ranged from 47% to 93%.

Color↗
PubMedDate not supplied

The effect of depth of dentin demineralization on bond strengths and morphology of the hybrid layer.

Previous studies have shown that different phosphoric acid-based etchants do not penetrate intertubular dentin to the same depth. The purpose of this study was to determine the effect of different phosphoric acid-based conditioners on dentin shear bond strengths of three one-bottle bonding systems and to evaluate the corresponding interfacial ultramorphology. The null hypothesis to be tested was that no correlation could be established between the depth of intertubular demineralization and dentin shear bond strengths. The labial surface of 90 bovine incisors was polished to expose middle dentin. The specimens were randomly assigned to three one-bottle adhesive systems (n = 30): OptiBond SOLO, Permaquick PQ1, and Single Bond. For each adhesive system the specimens were divided into three subgroups of different silica-thickened etching gels (n = 10): 37.5% phosphoric acid gel (Kerr Gel Etchant), 35% phosphoric acid gel (Ultraetch), and 35% phosphoric acid gel (Scotchbond Etching Gel). After 24 hours in water at 37 degrees C, the specimens were thermocycled for 500 cycles in baths kept at 5 degrees C and 55 degrees C and the shear bond strengths measured. The data were analyzed with one-way and two-way ANOVA. Further, the adhesives were applied to 800 microns-thick bovine dentin disks (two per subgroup), which were restored with a low-viscosity composite resin. Six small dentin/resin sticks with a cross-section of 1.0 mm x 1.0 mm were obtained from each bonded disk. They were then decalcified in a buffered solution of EDTA, fixed, stained, and sectioned in 90 nanometer-thick slices to observe under the Transmission Electron Microscope (TEM). The mean shear bond strengths were not statistically different at a confidence level of 95%. When the means were pooled for dentin adhesive and for etching gel, the number of cohesive failures was greater for Permaquick PQ1 and for Ultraetch, respectively. Pearson's correlation coefficient showed no correlation between hybrid layer thickness and bond strengths. The ultramorphological observation showed that all materials penetrated the dentin and formed a hybrid layer, regardless of the etching gel used.

Acid Etching, Dental↗
PubMedDate not supplied

Shear bond strengths of one-bottle dentin adhesives using multiple applications.

This study evaluated the effect of multiple applications of the one-bottle adhesives Prime & Bond, One-Step, and Tenure Quik on the shear bond strength of composite to dentin. In addition, the study examined the effects of surface moisture and dual-cure composite on bond strengths of One-Step and Tenure Quik respectively. The adhesive systems were bonded to the occlusal dentin of extracted human teeth. Control group specimens received only two applications of adhesive, as recommended by the manufacturers. Two experimental groups of each system received a greater number of adhesive applications. Additional experimental groups using only two adhesive applications were made to test modifications in surface moisture and composite type for One-Step and Tenure Quik. Shear bond strengths were determined using an Instron Universal Testing Machine. The mean shear bond strength of the Prime & Bond control group was significantly greater than that of the other two control groups. Multiple applications of adhesive decreased the bond strength of each system, but the difference was significant only for four applications of One-Step. The method of moisture removal (compressed air or blotting) had no effect on shear bond strength of One-Step. The shear bond strength of Tenure Quik was not affected by the type of composite used. Prime & Bond had significantly higher shear bond strengths to dentin than either One-Step or Tenure Quik. Both Prime & Bond and One-Step had significantly higher bond strengths than Tenure Quik.

Analysis of Variance↗