Clinical aspects of restorative treatment in the primary dentition.

The failure rate of restorative treatment in primary teeth was studied in a cohort of children born in 1981 and related to caries diagnosis, prevalence and distribution on different tooth surfaces, and compared with a cohort of children born in 1971. Concurrently, the longevity of composite resin in modified Class 2 cavities in primary molars was followed up and the resistance of deciduous and permanent enamel to acid adjacent to composite resin and glass polyalkeonate cement (GPA) was tested in vitro. From the 70s to the 80s, diagnostic methods changed and the examination intervals were prolonged. The number of bite-wing radiographs was halved and the participation in all six annual examinations decreased from 89% to 32%. Caries prevalence increased from 1.1 ds in 3-year-olds to 6.3 ds in 8-year-olds in Cohort '71 and, in the same ages, from 0.2 ds to 3.0 in Cohort '81. In Cohort '81, an overall decline of occlusal caries was recorded. The distal surface of the first molars was the proximal surface most often affected in both cohorts. In Cohort '81, 30% had caries-free primary teeth at the age of 8, which can be compared with 17% in the cohort 10 years earlier. In Cohort '81, the proportion of replaced proximal restorations was 14% and that of extracted molars 2%. The corresponding figures for Cohort '71 were 17% and 4%, respectively. In Cohort '81, silver amalgam was used in 65% and GPA cements in 35%. On all surfaces, silver amalgam was replaced in 22% and GPA cements in 6%. Composite resin in modified Class 2 cavities showed a cumulative success rate that declined from 86% after one year to 38% after six years. Fractures occurred early and recurrent caries was found from the second year of the follow-up. Histological investigation of these teeth disclosed bacteria subjacent to the fillings in 75% and recurrent caries in 58%. The restorations in teeth with bacterial invasion showed marginal discolouration, visible crevices or colour mismatch. In an acid environment, the enamel showed artificial caries lesions adjacent to composite resin significantly more often in primary teeth than in permanent teeth. No lesions were seen close to GPA fillings in primary teeth. The improved dental health appeared to be of greater benefit to the children and care-providers than advances in restorative treatment. The properties of GPA cements seem useful in the restorative treatment of primary teeth.