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Biomedical subjects

R DeVitre

Publications and source records attributed to R DeVitre.

6 recordsLinked to original sources
PubMed1985

Biometric comparison of bur and electrosurgical retraction methods.

A biometric comparison of two retraction methods was made on 20 adult patients who received complete crowns. Free gingival tissue height was recorded after 4, 8, and 12 weeks. The conclusions were (1) the electrosurgical method showed more tissue loss at each time interval than the bur method, (2) electrosurgical retraction showed more subject variability than the bur method, (3) clinically, the tissue appearance of both groups was indiscernable at the time intervals tested, and (4) the electrosurgical method provided for a greater bulk of impression material at the margin than the bur method.

Adult↗
PubMed1984

Effect of the dentin smeared layer on tensile strength of cemented posts.

The tensile strengths for post lengths of 4 and 7 mm were compared in vitro with 3 different cementing media. In one group, the post preparation was rinsed with 5.25% NaOCl and in the other with 17% EDTA followed by 5.25% NaOCl. The EDTA-NaOCl flush had a profound effect when unfilled resin was used to cement the posts. A 4 mm post cemented with resin in the EDTA-NaOCl group was one and one-half times as retentive as a 7 mm post cemented with zinc phosphate and twice as strong as the 7 mm post with polycarboxylate cement. The 7 mm post cemented with the resin after the EDTA-NaOCl rinse was twice as resistant to displacement as the 7 mm post cemented with zinc phosphate and three times stronger than the polycarboxylate cement.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1984

An SEM study of posts cemented with an unfilled resin.

Post preparations in two groups of endodontically treated anterior teeth were completed. In Group I, the preparation was rinsed with 2 ml of 5.25% NaOCL. In Group II, the preparation was rinsed with 1 ml of 17% EDTA, followed by 1 ml of 5.25% NaOCl. A plastic post was fitted and cemented with an unfilled resin. After polymerization, the teeth were decalcified in 5% nitric acid. The decalcified structured was dissolved away with 5.25% NaOCl, leaving a model of the cemented post. This was examined by SEM to determine the extent of resin penetration into the dentinal tubules. In Group I, most of the post was smooth, and there was penetration only in small, random areas. In Group II, there was penetration into the tubules the full length and circumference of the post. Such penetration provides a very strong mechanical lock that enhances the tensile strength of the cemented post. Removing the smeared layer and then cementing a post with a Bis-GMA resin results in greatly increased tensile strength, even with shorter posts.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1984

Cement distribution and bond strength in cemented posts.

Rods of lucite were drilled to receive a No. 5 parapost to a depth of 4 mm and 7 mm. Posts were fitted and cemented either by coating the post with cement or by placing the cement in the prepared hole with a lentulo spiral in a low-speed hand-piece and then inserting the pre-coated post. Photographs were taken to determine the distribution of the cement. The lentulo spiral distributed the cement along the entire length of the preparation, but coating alone did not distribute the cement evenly. The tensile strength with these two methods of post cementation was also compared in four groups of extracted teeth. In Groups IA and IIA, the post preparation was rinsed with 2 ml of 5.25% NaOCl and dried with paper points and blasts of air. In Group IA, the post was coated with zinc phosphate cement and seated. In Group IIA, the cement was placed into the post space with a lentulo spiral in a slowly rotating hand-piece; the post was then coated and seated. In Groups IB and IIB, the post preparation was rinsed with 1 ml of 17% Na2 EDTA followed by 1 ml of 5.25% NaOCl to remove the smeared layer at the dentin-cement interface. The posts were then cemented as in IA and IIA. Under the conditions of this experiment, the following conclusions can be drawn: Placing cement into the preparation with a lentulo spiral increased the tensile strength and the overall cement distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Cementation↗