Periodontal microbiota of mobile and non-mobile teeth.

The mechanism of accelerated periodontal destruction around teeth with occlusal trauma and increased mobility remains unclear. One possibility is that tooth mobility creates a subgingival environment conducive to overgrowth by periodontal pathogens. This study compared the subgingival microflora in mobile and non-mobile teeth of 35 adults on supportive maintenance therapy and 15 with untreated adult periodontitis. In each subject, subgingival paper-point samples were obtained from a mobile tooth with a probing depth of 4 mm or greater and from a non-mobile tooth with similar probing depth and gingival index. Samples were transported in VMGA III medium. Pockets around mobile teeth harbored significantly higher proportions of Campylobacter rectus (P = 0.001) and Peptostreptococcus micros (P = 0.05) than pockets with non-mobile teeth. Mobile teeth also tended to show elevated levels of Porphyromonas gingivalis, but this did not reach statistical significance. This study suggests that tooth mobility may constitute a risk for periodontal breakdown due to an increased subgingival occurrence of specific periodontopathogens. This hypothesis needs to be verified in longitudinal clinical and microbiological studies.

The influence of trauma from occlusion on the bacterial repopulation of periodontal pockets in dogs.

Pockets were surgically created in the two upper external incisors of four beagle dogs, and a copper band adapted to prevent reattachment. After 4 weeks the copper bands were removed, the teeth scaled and root-planed and crowns placed on both experimental teeth in such a way that one of them was forced bucally when the teeth occluded. An orthodontic appliance anchored in bands cemented to the cuspid teeth brought the tooth back to its original position when disclusion occurred. Experimental time was 12 weeks. Clinical indices and bacterial samples for darkfield examination were taken at baseline and weekly thereafter. The dogs were fed a diet that favored plaque accumulation and no oral hygiene was performed. Surgically created pockets initially became populated by cocci (65%-75%) and small amounts of motile bacteria (12%-15%) including 3% to 4% spirochetes. In 4 weeks the percentage of cocci declined steadily (42%-45%) and motile bacteria increased to 37% to 43% with spirochetes representing 24% to 27%. After scaling and root planing, the number of cocci increased again and motile bacteria declined although the baseline values were not reached. This decline persisted for 2 weeks after scaling. Repopulation of the pocket in traumatized and nontraumatized teeth followed the same initial pattern, taking again 5 weeks to return to prescaling levels. No difference was found between traumatized and nontraumatized teeth. Clinical measurements, however, revealed a statistically greater loss of attachment in traumatized teeth as compared with nontraumatized teeth.