Subgingival plaque and loss of attachment in periodontosis as evaluated on extracted teeth.

The correlation between downgrowth of subgingival plaque and loss of attachment was evaluated on 27 teeth which had to be extracted because of advanced bone loss in 16 patients between ages 12 and 22. The diagnostic criteria were those used for periodontosis. The teeth were stained and examined under the stereomicroscope. There was a very high degree of congruence between the subgingival plaque front and the line of lost attachment on all the teeth, thus showing that plaque is strongly involved in the destruction of the attachment apparatus. On some of the vestibular and lingual surfaces where efficient supragingival plaque control had been maintained, there was no subgingival plaque and no loss of attachment, showing that subgingival plaque develops from supragingival plaque. The highest speed of apical growth of the subgingival plaque front in any one case was estimated to be about 5 mu per day, or about 1,8 mm per year. Such an unusually rapid advancement must be the combined effect of an extremely high invasiveness of some inhabitants of the plaque and some deficiency in the host's defense mechanism against the same organisms. The subgingival plaque was found to be very thin and only occasionally calcified to form calculus. Symptoms of inflammation, if any, were only seen at the gingival margin, giving the clinical impression of a noninflamatory, degenerative condition. This explains why the concept of diffuse atrophy has developed. The observations made in this material indicate that what has been diagnosed as periodontosis, in fact is a highly destructive juvenile periodontitis which should be so named. The high destructiveness depends on a host parasite imbalance rather than on a degenerative condition.