Comparative quantitative and qualitative assessment of the marginal adaptation and apposition of bonded amalgam restorations using luting glass ionomer and 4-META adhesive liner under a scanning electron microscope. An in vitro study.

The present invitro study was conducted to assess the marginal adaptation and apposition of amalgam restorations bonded to tooth structure, using freshly mixed luting glass ionomer cement (type 1) and compared with the much documented material--Amalgam bond (4-META). Twelve freshly extracted human premolar teeth were used and class V cavities were prepared on the buccal and lingual surfaces of twelve teeth for the experimental groups. Buccal cavities (class V) were prepared on twelve other teeth for the control group. In the control, two coats of cavity varnish was applied as the liner. The experimental groups were lined with freshly mixed luting glass ionomer in twelve buccal cavities and amalgam bond adhesive liner in twelve lingual cavities. The amalgam was then condensed before the liner sets in all the cavities. The teeth were sectioned and mounted on aluminum stubs and then placed in the scanning electron microscope and were observed. The results of the study showed that marginal interface gaps were higher with luting glass ionomer and cavity varnish than with amalgam bond as the liner. The results were statistically not significant. All the three groups were effected by the severe thermal stresses introduced by the microscopy with the glass ionomer cement suffering the worst. The present investigation confirms that glass ionomer cement (type 1) can be effectively used as a bonding agent between amalgam and the tooth when it is painted onto the cavity walls after which the amalgam is condensed immediately, prior to its setting. Its ability to bond amalgam to the tooth structure with minimal gaps is comparable to that of amalgam bond.