Periodontal tissue formation in furcation defects following reconstructive therapy. Experimental studies in the dog

The experimental studies included in the present thesis were performed in dogs and evaluated various aspects of periodontal tissue formation in degree III furcation defects. The third mandibular premolars were used as experimental units and healing was studied in biopsy material sampled at various time intervals following guided tissue regeneration therapy (GTR).In study I, two experiments were performed, a and b. In both experiments, degree III furcation defects were produced and reconstructive surgery was performed. In experiment a, e-PTFE barriers were placed in one side of the mandible while in the contralateral side no barrier was used. In experiment b, defects of different dimensions were produced. Resorbable Resolut® barriers were placed in one side of the mandible while in the contralateral side, non-resorbable e-PTFE barriers were applied. After 5 months of healing, the animals were sacrificed and biopsies were prepared for histological analyses. The findings showed that GTR, using either non-resorbable or resorbable barriers, had resulted in the resolution of both small and large furcation defects. In study II, the new formation of periodontal tissues at different time intervals (2, 4, 8, 20 weeks) was described. The results suggested that the formation and organisation of the periodontal tissues apparently occurred through an orderly sequence of events. In study III, the tissue which had formed 5 months after reconstructive therapy was analysed and compared with the periodontal tissues of pristine furcations. It was demonstrated that the healed furcations differed in many aspects - such as type of cementum and amount of mineralized bone - from the pristine furcations. Study IV evaluated GTR when different types of resorbable barriers were applied; Resolut® and Guidor®. Healing was allowed for 6 months. It was observed that both barriers allowed the formation of a new attachment. The presence of a granulomatous tissue in the apical part of defects at which a Guidor® barrier was applied, however, prevented bone regrowth at such sites. In study V, the effect of enamel matrix proteins (Emdogain®) in conjunction with GTR was evaluated. Healing was allowed for 4 months. The histological examination revealed that Emdogain®, topically applied on the root surface during surgery, may promote the formation of a new acellular cementum in an apical portion of the furcation defect