Presence or absence of plaque on subgingival restorations.

One hundred and eight extracted teeth with restorations placed below the gingival margin were stained and examined under the stereomicroscope with the aim of scoring presence or absence of subgingival plaque. Individual observations showed that a subgingival restoration can be completely covered with plaque in as short a time as 6 weeks and it can be free of plaque for as long as 2 years. In the material as a whole about 9 out of 10 of the restorations were covered with plaque subgingivally. Since the material is selected, these proportions cannot be claimed to be valid for the population as a whole, but the observations suggest that plaque sooner or later will accumulate on most if not all subgingival restorations. Rough surfaces and or inadequate marginal adaptation are likely to facilitate a more rapid adherence of bacteria to the restorations than to the smooth tooth surface. It is concluded that restorations placed below the gingival margin indirectly are stongly involved in the etiology of destructive periodontal disease and the cause of many extractions.