Marginal leakage of Class II glass-ionomer-silver restorations, with and without posterior composite coverage: an in vitro study.

The aims of this in vitro investigation were: 1) to assess marginal leakage around three types of class II restorations, using: a) a composite resin with a glass ionomer lining; b) a glass ionomer cerment with composite resin coverage; c) a glass ionomer cermet without composite resin coverage and 2) to study the effect of thermocycling on marginal defects, by means of radiographs and SEM micrographs of the margins. Fifty-eight class II cavities were prepared in extracted primary molars. The teeth were divided into three groups and restored as follows: Group A--Ketac Bond (liner) and P-30; Group B--Ketac Silver and P-30(sandwich); Group C--Ketac Silver only. The restored teeth were thermocycled and marginal leakage was assessed from the degree of dye penetration on the sections. Dye penetration at the occlusal margins increased in the sequence A less than B less than C. The differences between group C and Groups A and B were statistically significant. Severe penetration of the dye was observed at the cervical margins with no statistically differences between the groups. Deterioration of margins due to thermocycling was observed for all groups, but these defects were not evident on the radiographs. Ketac Silver with and without composite coverage did not prevent marginal leakage when utilized in class II restorations in vitro.