TOOTH MOBILITY AND RESOLUTION OF EXPERIMENTAL PERIODONTITIS - AN EXPERIMENTAL-STUDY IN THE DOG

The aim of the present experiment was to study alterations in the mobility of teeth that occurred during resolution of experimentally induced periodontitis lesions in the dog. 5, 1-year-old, beagle dogs were used in the study. The left and right 4th, 3rd, and 2nd mandibular premolars (P-4(4), P-3(3), P-2(2)) served as experimental teeth. Periodontal tissue breakdown was initiated by placing plaque-collecting cotton-floss ligatures around the neck of the experimental teeth. The ligatures were replaced to the level of the receding gingival margin 1 x every month. On Day 120, the ligatures were removed and debridement was performed. A groove, parallel to the long axis of the mesial root, was prepared in the mesio-buccal surface of the crowns Of 2P and P2. Guided by the groove and with a probing force of 0.5 N, a probe was inserted into the buccal gingival pocket of the mesial root and was attached to the buccal surface. Biopsies including both the mesial and distal root of 2P and P2 and the surrounding hard and soft tissues were harvested. The biopsy procedure was repeated in a similar manner 15 days (i.e. Day 135) and 3 months (i.e. Day 225) after ligature removal in the 4th (P-4(4)) and 3rd (P-3(3)) premolar regions. After fixation, decalcification and sectioning, the biopsy material was exposed to histometric and morphometric measurements. Assessment of the mobility of the experimental teeth was performed on Days 120, 135 and 225 using the Periotest system. The amount of remaining bone at the experimental teeth was evaluated in radiographs obtained in a standardized manner. The findings of the present experiment disclosed that in dogs allowed to form plaque, the placement of cotton-floss ligatures at the neck of mandibular premolars initiated a process that resulted in (i) the formation of an inflammatory lesion which extended deep into the supracrestal connective tissue; (ii) extensive loss of alveolar bone; (iii) markedly increased tooth mobility. It was also observed that, within a 4-month period the removal of the ligature and, as a consequence, a substantial portion of the subgingival microbiota, reduced the size and the apical extension of the inflammatory lesion in the supracrestal connective tissue. The alterations in the soft supracrestal tissue were accompanied by a marked decrease in the mobility of the experimental teeth and a reduced probing pocket depth. It was suggested that the reduced penetration of the probe was the result of the change in the size and position of the infiltrate as well as of a reduced mobility of the experimental teeth.