The changes of the periodontal tissues irritated mechanically by small active elastic rings on the survival portion of the right first molar were observed microscopically in germfree and conventional JCL: SD strain rats.
The results obtained were as follows:
1. Pocket formation, slight infiltration of inflammatory cells into the periodontal tissues and hyaline degeneration or disappearance of the gingival fibers in some degree were noticed in germfree rats.
2. More sever inflammatory changes of the periodontal tissues such as epithelial acanthosis, ulceration, disappearance of the gingival fibers, wide spread inflammatory cell infiltration, alveolar bone destruction and abscess formation in the bifurcation of the teeth in conventional rats were distinctly recognized than in the germfree rats.
3. The depth of the pockets in conventional rats was 0.8mm to 0.9mm and about twice of the depth in germfree rats.
