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Biomedical subjects

R D Davis

Publications and source records attributed to R D Davis.

151 records · Page 9Linked to original sources
PubMedDate not supplied

The influence of matrix use on microleakage in Class 5 glass-ionomer restorations.

This in vitro study examined the relationship of matrix use to microleakage in class 5 Ketal-Fil glass-ionomer restorations. Class 5 glass-ionomer restorations were placed on the facial and lingual surfaces of 40 extracted human molars. The occlusal margin was located on enamel, and the cervical margin was located on cementum or dentin. Each tooth had one restoration placed with and without the aid of a soft metal matrix. Specimens were thermocycled (1234 cycles, 6 degrees C -60 degrees C, 30-second dwell time) and immersed in 5% methylene blue dye for four hours. The teeth were sectioned occlusogingivally through the center of each restoration, viewed with an optical microscope (X10), and each restoration was scored for dye penetration around the cavity walls. The enamel and cementum margins were scored separately for the extent of marginal leakage. No difference in leakage was found between restorations placed with or without a matrix (P > 0.05). Enamel restorations leaked significantly less than nonenamel margins, regardless of matrix use (P > 0.05).

Dental Cementum↗
PubMedDate not supplied

Platinate toxicity: past, present, and prospects.

Using traditional toxicologic methods, four species were studied for their qualitative and quantitative predictiveness of the toxic effects of cis-dichlorodiammineplatinum(II) in man. Of the four species studied, mouse, monkey, rat, and dog, the latter two gave the best overall results. Using an in vivo rat model, it was found that except for chloroplatinic acid, eight of the tested analogs were less nephrotoxic than the parent drug, cis-dichlorodiammineplatinum(II). The in vitro renal toxicity screen using flounder tubules showed that of the 26 compounds studied, about half were less toxic than the parent compound. This in vitro mini-tox system can be performed about 30 times faster and at one fiftieth the cost of the in vivo model. The in vitro studies also provided evidence that the biochemical site of toxicity of platihates is on ATPases. The latter studies suggested a basis for unifying the mechanistic interpretation of the toxic actions on such disparate target organs as the kidney, nerve, stomach, and inner ear.

Adenosine Triphosphatases↗
PubMedDate not supplied

Microleakage associated with resin composite-cemented, cast glass ceramic restoration.

Resin cements are the preferred luting media for ceramic restorations, but manufacturers have traditionally made no recommendations concerning the use of dentin bonding agents in the luting process. This in vitro study evaluated the microleakage associated with several luting agents for ceramic inlays. One hundred twenty Class V inlays (occlusal margins in enamel and gingival margins in dentin) were luted in extracted teeth using zinc phosphate cement, two resin cements without a bonding agent, and two resin cements with three dentin bonding agents. This study suggests that the use of a dentin bonding agent with a resin cement will reduce microleakage in cast glass-ceramic restorations.

Acrylic Resins↗
PubMedDate not supplied

Evaluation of tin plating systems for a high-noble alloy.

The tensile bond strength of Panavia EX to a high-noble alloy prepared by abrasive spraying and tin plating was measured. Two different intraoperatory tin plating systems were compared. Disk-shaped specimens were cast in type III gold, abrasive sprayed with aluminum oxide, and divided into three groups of 30 specimens each. Specimens in one group were tin plated by using a Kura Ace Mini unit, those in the second group were tin plated by using a Micro Tin unit, and those in the third group were not tin plated and served as the control group. Disks within each group were luted to each other with Panavia EX. The specimens were thermocycled and tested in tension. There was no significant difference between the two tin plated groups; however, the luting bond of both experimental groups was significantly stronger than was that of the control (P < .05).

Analysis of Variance↗