In a randomized controlled trial, self‐teaching booklets and computer media were evaluated for teaching diagnostic testing to dental students as a foundation for further development of clinical decision making skills. Effectiveness was assessed by pre‐ and post‐tests. Reliability of these test instruments was examined by analyzing the pre‐ and post‐test scores of 49 first year dental students who received no instruction. Forty‐one second year dental students were exposed to clinical epidemiological principles applied to endodontic diagnosis through either self‐teaching booklets or computer media. No statistically significant difference was found between the mean test scores of the students through self‐teaching booklets and computer media. Although first and second year students showed a statistically significant improvement between the pre‐test and post‐test, the improvement in the second year class was greater. An addendum was later made to the main trial to compare the self‐teaching booklet to the traditional lecture format in teaching endodontic diagnosis. Seventy‐one third year dental students were exposed to these same materials through either a lecture or the self‐teaching booklet and then similarly tested. There was no significant difference between the self‐teaching booklet and traditional lecture for the third year students.

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Multimedia teaching tools in dental education are still rare. This paper describes the development of an inexpensive yet powerful computer program for instruction in the principles of clinical epidemiology. The application was developed in the context of periodontal diagnostic methodologies at the third year D.D.S. level. Principles of probabilistic thinking are invoked as the student is guided from the application of raw research data to the derivation of likelihood ratios and how they affect clinical decision making. A questionnaire was used to evaluate student satisfaction with the program and the responses indicated good acceptance of the concepts presented in the program and an interest in further computer‐aided instruction.

Bone marrow stromal cells are a mixed population that contribute to the formation of the hematopoietic microenvironment. The osteogenic lineage includes populations of cells that, in culture, form discrete nodules of mineralized tissue when grown in the presence of ascorbic acid and sodium beta-glycerophosphate. We have used nodule formation to assay for the self-renewal capacity of osteoprogenitor cells in chick bone marrow cultures. To examine the regulatory influence of dexamethasone (Dx), first subcultures were grown continuously or split 1:1 at repeated subculture. Cells in continuous culture exhibited less than two population doublings, while cellular proliferation and alkaline phosphatase area were inhibited by 10(-8) mol/L Dx. Cells in split (redistributed) cultures exhibited up to 14 population doublings and cellular proliferation was also inhibited by Dx. In contrast with continuous cultures, redistributed cultures treated with Dx had increased alkaline phosphatase area and 15-fold larger amounts of mineralized tissue formation than controls. Osteogenesis was sustained for up to four subcultures and the ratio of mineralized tissue area to alkaline phosphotase positive cell area was at most 0.55. These data indicate that the osteogenic lineage of bone marrow stromal cells contains self-renewing progenitors that are recruited by Dx in culture and that at a maximum, only 55% of the alkaline phosphatase-positive cell population contributes to osteogenesis.

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