INFLUENCE OF AMALGAMS, BASES, AND VARNISH ON SEAL COMPOSITION AT RESTORATION TOOTH INTERFACES

Eighty extracted, noncarious premolars were restored with one of 20 di fferent combinations of restorative materials: a high- or low-copper a malgam, unlined or lined with one of five bases, and varnished or unva rnished. The teeth were aged in 1% NaCl and after 3 months and 1 year the seal material deposited on the cut tooth cavity surface and the su rface of the amalgam restoration was analyzed by use of energy dispers ive x-ray analysis. Atomic weight percentages of marginal seal element s were statistically examined with ANOVA and Tukey's test with signifi cance set at p < 0.05. The results indicated that only one type of sea l was formed centered around tin. More marginal seal material was pres ent in the 1-year specimens. Restoration materials used affected the d eposition rate of marginal seal material. Low-copper amalgam-restored teeth formed more seal material with significantly greater amounts of chlorine and tin. Less marginal seal material was found in varnished c avities. A calcium hydroxide base produced a thick marginal seal with a significantly different composition of elements compared with the un lined and zinc-based specimens. Tin in Poly-F Plus polycarboxylate cem ent did not significantly increase the tin content of the marginal sea l. Base materials can play a role in determining crevice pH. The findi ngs have bearing on improved longevity of amalgam restorations.