Histobacteriological analysis of acid red dye-stainable dentin found beneath intact amalgam restorations.

This study determined histologically the incidence of acid red dye-stainable dentin and its correlation to bacterial presence beneath intact clinically sound amalgam restorations. Fourteen of 16 clinically sound amalgam restorations (88%), serving an average of 11 years, had microscopically evident microorganisms in the subjacent dentin. Eleven of the 14 specimens containing bacteria (79%) exhibited acid red dye-stainable dentin. There was no obvious correlation between dye-stainable dentin and the presence of bacteria on the walls of the cavity preparations studied. The question of how much dye-stainable dentin can be present beneath an amalgam restoration before the restoration fails is still unanswered.

Microleakage of castings cemented with glass-ionomer cements.

When metal copings were luted to prepared, extracted teeth with KetacCem, ChemBond, TempBond, and zinc-oxide-eugenol (ZOE), only thermocycled ZOE exhibited severe leakage. It appears unlikely that postcementation microleakage is the cause of tooth sensitivity associated with the use of glass-ionomer cements.

Histological study of an acid red caries-disclosing dye.

When 20 extracted teeth were examined histologically after using a 1.0% acid red caries-disclosing dye before excavation of carious dentin, 25% showed the presence of bacteria in the dentin. The use of a solution of 1.0% acid red in propylene glycol to identify infected dentin will greatly decrease but not completely eliminate the changes of viable bacteria remaining in a cavity preparation.

Immunohistochemical localization of amelogenins in enameloid of lower vertebrate teeth.

The indirect method of immunofluorescence was used to demonstrate the presence of amelogenins in the enameloid of teeth and dermal denticles of Chondrichthyes; in the enameloid of Teleostei and Amphibia; and in the enamel of Reptilia. Nonmammalian amelogenins are formed in the ectodermal cells of tooth organs and chemically are so similar to mammalian amelogenins that they interact with antiserum prepared from bovine enamel matrix.

Immunofluorescent evidence for the similarity of amelogenins in calf, mouse and pig teeth.

Antiserum was prepared to fetal bovine enamel matrix and was used to localize the amelogenins in developing bovine molars by immunofluorescent microscopy. Amelogenins could be identified to preameloblasts, secretory ameloblasts, stratum intermedium cells, and the newly deposited enamel matrix. Mature enamel matrix did not fluoresce except in a thin line along the DEJ and adjacent to the ameloblasts. Immature enamel matrix of murine and porcine teeth fluoresced when treated with antiserum to bovine enamel matrix. No other portions of tooth buds or other tissues reacted with the specific antiserum.

Re-regeneration of lower jaws and the dental lamina in adult urodeles.

Transverse amputations were carried out through one-third fully regenerated jaw segments and through normal tissue of the mandible on the same and opposite sides of the jaw in adults of Notophthalmus viridescens. Collectively the results suggest that, in adult urodeles, the mandible and the dental lamina can be replaced in an identical manner more than one time. Although the major histological events are the same in jaw regeneration and re-regeneration, regrowth is more rapid in re-regeneration. It appears that recently differentiated tissues of the regenerate have a higher capacity for regeneration than normal tissues amputated for the first time. Re-regeneration of the jaw occurs by growth of the original regenerate cartilage which has undergone reorganization. In re-regeneration, the skeletal elements exhibit no polarity and regrowth occurs in both directions, while the dental lamina possesses an anterior-posterior polarity and can regrow in an anterior direction only. Information concerning the mechanisms involved in the regenerative events remain to be determined.

Proteins and insulin release: a dual role of amino-acids and intestinal hormones.

In two subjects concurrent infusion of amino-acids and the hormones secretin and pancreozymin provoked much higher plasma insulin levels than did administration of amino-acids or hormones individually. It is suggested that this may be a physiological phenomenon, augmenting the release of insulin from the pancreas after a meal containing protein.