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 mobi lity of teeth that occurred during resolution of experimentally induce d periodontitis lesions in the dog. 5, 1-year-old, beagle dogs were us ed in the study. The left and right 4th, 3rd, and 2nd mandibular premo lars (P-4(4), P-3(3), P-2(2)) served as experimental teeth. Periodonta l tissue breakdown was initiated by placing plaque-collecting cotton-f loss ligatures around the neck of the experimental teeth. The ligature s were replaced to the level of the receding gingival margin 1 x every month. On Day 120, the ligatures were removed and debridement was per formed. A groove, parallel to the long axis of the mesial root, was pr epared 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 roo t of 2P and P2 and the surrounding hard and soft tissues were harveste d. 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 4t h (P-4(4)) and 3rd (P-3(3)) premolar regions. After fixation, decalcif ication and sectioning, the biopsy material was exposed to histometric and morphometric measurements. Assessment of the mobility of the expe rimental teeth was performed on Days 120, 135 and 225 using the Periot est system. The amount of remaining bone at the experimental teeth was evaluated in radiographs obtained in a standardized manner. The findi ngs of the present experiment disclosed that in dogs allowed to form p laque, the placement of cotton-floss ligatures at the neck of mandibul ar premolars initiated a process that resulted in (i) the formation of an inflammatory lesion which extended deep into the supracrestal conn ective tissue; (ii) extensive loss of alveolar bone; (iii) markedly in creased tooth mobility. It was also observed that, within a 4-month pe riod 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 t issue. The alterations in the soft supracrestal tissue were accompanie d by a marked decrease in the mobility of the experimental teeth and a reduced probing pocket depth. It was suggested that the reduced penet ration of the probe was the result of the change in the size and posit ion of the infiltrate as well as of a reduced mobility of the experime ntal teeth.