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Biomedical subjects

R W Phillips

Publications and source records attributed to R W Phillips.

At least 307 records · Page 17Linked to original sources
PubMedDate not supplied

In vitro wear response of composite resin, amalgam, and enamel.

A two-body, wear-testing method was developed and the test results were used for comparing and ranking the rate of wear for an amalgam, an experimental composite resin, and a commercial composite resin. The ranking of wear found by this method was the same as that shown by clinical research for the rate of wear of amalgam and commercial composite resin.

Composite Resins↗
PubMedDate not supplied

Thermal diffusion through amalgam and cement base: comparison of in vitro and in vivo measurements.

Thermal diffusion was measured in vitro and in vivo through amalgam and amalgam underlaid with bases of zinc phosphate, zinc oxide-eugenol, and calcium hydroxide cements. Although the magnitudes differed, there generally was good agreement between in vitro and in vivo data with respect to the relative rates of thermal diffusivity through amalgam restorations underlaid with bases of each of the three materials. In all tests, both in vitro and in vivo, the zinc oxide-eugenol base proved to be the best thermal insulator. Calcium hydroxide was the next best thermal barrier and was followed by zinc phosphate cement. In vitro tests indicated dentin to be a better thermal insulator than zinc phosphate cement but inferior to the zinc oxide-eugenol and calcium hydroxide base materials used here. Although a method has been presented here for the in vivo assessment of the efficacy of thermal insulating bases and a number of in vivo experiments were conducted, much research remains to be done in this area. Additional investigation is needed to better define the parameters of thermal change beneath various types of restoratives and also to establish more exactly the role of base thickness in providing thermal protection beneath clinical metallic restorations.

Calcium Hydroxide↗
PubMedDate not supplied

Addition of fluoride to pit and fissure sealants--a feasibility study.

The data obtained in this in vitro study indicate that contact with pit and fissure sealants to which NaF has been added in amounts ranging from 2 to 5% substantially increases the fluoride content of the enamel and reduces its solubility in acid. The properties of the materials do not seem to be impaired by the addition of fluoride in these amounts. It thus appears that this approach to providing a backup anticariogenic mechanism may, indeed, be feasible. However, further investigation must be done to confirm the anticariogenic effect and to establish the most efficacious means of fluoride incorporation in the materials.

Acrylic Resins↗
PubMedDate not supplied

Clinical performance and physical properties of twelve amalgam alloys.

An assessment of the marginal failure rate of 1,041 restorations of twelve alloys was made at one year. In addition, physical property tests were conducted. A correlation was found between the clinical performance and creep (.79), flow (.62) and 24-hour compressive strength (.60).

Chemical Phenomena↗
PubMedDate not supplied

Comparison of two tests to determine the castability of dental alloys.

This study compared castability values in the Whitlock test with those obtained from a new castability monitor based on a dental restoration. Five metal ceramic casting alloys were induction cast with both a carbon-containing and a noncarbon phosphate-bonded casting investment to assess the reliability of the Whitlock mesh test in predicting alloy castability. Alloy performance in the Whitlock test did not parallel that of the replica coping test for all alloy-investment pairs, as would be anticipated for a reliable monitor of castability. In addition, the variability of the Whitlock castability values for some alloys was sufficient to question the test's usefulness in refining the casting process with a specific alloy.

Analysis of Variance↗
PubMedDate not supplied

Comparative study: bond strength and microleakage with dentin bond systems.

Four commercial bond agent-composite systems were tested with respect to the strength of the bond to bovine dentin and their ability to seal class 5 erosion lesions without cavity preparation. At seven days there was no significant difference in the bond strengths of the four bonding agents, Scotchbond, Gluma, Tenure, and Scotchbond 2. Restorations placed with Gluma had significantly less leakage than those placed with other bond agents. At 90 days the bond strength of Tenure was reduced and was significantly less than that of the other systems, while Gluma and Scotchbond 2 restorations exhibited significantly less leakage than Scotchbond and Tenure. There was an inverse correlation (r2 = .5460) between bond strength and marginal leakage of class 5 restorations.

Animals↗