Temporary restorations: advantages and disadvantages.

The reaction of tissue to temporary restorations was studied in four young dogs and four young monkeys. A total of 56 cavities were prepared and filled with gutta percha, self-curing acrylic resin, or zinc oxide and eugenol cement. Attempts were made to finish the preparations at the deepest point of the existing clinical pocket, which invariably was found to coincide with the cemento-enamel junction. All the animals had the teeth on the left side brushed every day. The observation periods varied between 13 and 283 days. Immediately before the animals were killed by an overdose of Nembutal, the presence or absence of gingivitis was recorded. A series of sections were cut in the area of the cavity, as well as just outside it. The following observations were made: Examination of the sections from outside the cavities verified that the preparations had been made in pockets with soft walls made up of the junctional epithelium. The cavities ended shortly above the cemento-enamel junction (Figs. 3, 4, 6, and 8) or below it (Figs. 1, 2, 5, 7, and 9 to 11). The adaptation of the fillings was never perfect in all parts of the cavity at the same time. The pocket epithelium was regenerated within 13 days. Plaque formation first started in the open spaces between the preparation and the fillings. Subsequently, the plaque spread over the surfaces of the fillings and eventually over the tooth surface below them. The fillings invariably induced submarginal gingivitis, even in the absence of plaque. Presence of plaque exacerbated the inflammatory reaction, but the loss of attachment was limited to less than 0.2 mm as long as the plaque was confined to the fillings. Significant loss of attachment was always associated with apical growth of the subgingival plaque. The submarginal gingivitis was not manifested clinically if the fillings were brushed daily, because vigorous tooth brushing had an effect as far as 0.7 mm below the gingival margin.