Centric relation definitions taught in 7 dental schools: results of faculty and student surveys.

PURPOSE: The purpose of this investigation was to assess the level of consensus regarding the definition of centric relation and its clinical use in 7 US dental schools. MATERIALS AND METHODS: The preclinical and clinical faculty in the departments of prosthodontics, operative, and general dentistry (n = 137) at 7 dental schools and a convenience sample of fourth year students (n = 150) at the same schools were invited to complete 2-page surveys regarding the definitions and use of centric relation at their institutions. The faculty and student survey included 6 commonly used centric relation definitions from the 1994 Glossary of Prosthodontic Terms, and provided space for writing in definitions not listed on the form. The participants were asked to identify which definition was used at their school. RESULTS: Return rate was 85% for faculty and 75% for students. Both faculty and students identified a low level of consensus regarding the definition and clinical use of centric relation at their dental school. Numerous definitions are in use at each institution. Extramural practice participation and the number of years since dental school graduation were variables associated with the faculty's choice of definition. The faculty who did not participate in an extramural practice chose older definitions. Dental educators graduating before 1975 selected either the oldest or the most recent centric relation definition, whereas the more recent graduates frequently selected the newer definitions. There were no statistical differences between prosthodontic specialists and nonspecialists in choice of definitions. Three courses identified by the students as having the most influence on their understanding of centric relation were preclinical removable prosthodontics, preclinical occlusion, and clinical removable prosthodontics. CONCLUSION: The results of this survey suggest that the controversy will continue, because to date there is no consensus regarding the definition of centric relation within the 7 dental schools surveyed.

Educating a patient with dental implants.

A functional dentition can be restored for edentulous and partially edentulous patients through the placement of dental implants. Dental assistants have a significant role in the education of implant patients so that meticulous oral self-care can be accomplished. Only through the combined team efforts of the dental office staff and patients themselves will the continued success of dental implantology be insured.

The effects of chlorhexidine on the attachment and growth of cultured human periodontal cells.

The purpose of this investigation was to evaluate the effects of chlorhexidine (CHX) on the attachment and growth of human gingival fibroblasts and periodontal ligament cells using an in vitro system where periodontal cells were grown on root surfaces treated previously with CHX. Our results indicate that the attachment of periodontal cells onto root surfaces was not adversely affected when roots were treated for 15 minutes with up to 0.12% CHX. However, cell attachment and morphology were adversely altered with prior 0.2 to 2.0% CHX treatment. The cells appeared round and retracted from roots treated with 0.2% CHX. With 2% CHX treatment, the cells exhibited a foamy appearance in which most of the cytoplasm seemed to have been extracted from the cells. Although 0.12% CHX treatment did not adversely affect the attachment of periodontal cells onto roots, direct exposure to as little as 0.01% CHX caused a 90% reduction in 3H-thymidine incorporation by cultured gingival fibroblasts. We conclude that although 0.12% CHX did not inhibit the attachment of cultured periodontal cells to pretreated roots, direct exposure of cells to much lower concentrations of CHX (0.0025 to 0.01%) caused a dose-dependent inhibition of growth.

Prostaglandin E2 is a positive regulator of adrenocorticotropin receptors, 3 beta-hydroxysteroid dehydrogenase, and 17 alpha-hydroxylase expression in bovine adrenocortical cells.

The maintenance of optimal steroidogenesis in adrenocortical cells primarily depends on the chronic action of cAMP. Herein we examine the effects of prostaglandin E2 (PGE2) on the differentiated functions of bovine adrenocortical (BAC) cells in primary culture. PGE2 (10 microM) treatment for 3 h stimulated steroidogenesis and cAMP production by over 100-fold. In addition, the cAMP antagonist Rp-cAMP (1 mM) inhibited PGE2 stimulation of steroidogenesis by 60%. This observation suggests that the cAMP second messenger system is responsible for much of the PGE2-activated steroid hormone synthesis. Chronic treatment of BAC cells with PGE2 caused induction of 3 beta-hydroxysteroid dehydrogenase and steroid 17 alpha-hydroxylase cytochrome P-450 expression as determined by the examination of enzyme activity, enzyme levels by immunoblotting, and specific messenger RNA (mRNA) levels by Northern analysis. The positive effects of PGE2 on expression of 3 beta-hydroxysteroid dehydrogenase and 17 alpha-hydroxylase cytochrome P-450 were similar to the effects seen after ACTH treatment of BAC cells. In addition, treatment of BAC cells with PGE2 for 3 days caused a 3-fold induction of ACTH receptors as determined by increased cell binding of [125I]ACTH. Finally, we determined that BAC cells produced PGE2 and that the level of synthesis increased 10-fold after treatment with the hormone angiotensin II. Taken together these data indicate that PGE2 is a positive regulator of BAC cell differentiation acting on ACTH receptors, steroid metabolizing enzymes, and steroidogenesis. The ability of BAC cells to produce PGE2 leaves open the possibility for paracrine and autocrine regulation within the adrenal.