GTR TREATMENT OF DEGREE-III FURCATION DEFECTS FOLLOWING APPLICATION OF ENAMEL MATRIX PROTEINS - AN EXPERIMENTAL-STUDY IN DOGS

The aim of the present study was to evaluate the effect of enamel matr ix proteins (EMD) on periodontal wound healing in degree III furcation defects in dogs. The experiment was performed in 5 foxhound dogs. 2 m onths prior to the start of the experiment, the 2nd and 4th lower prem olars were extracted. Degree III furcation defects were created in the 3rd mandibular premolars (P-3(3)) The furcation defects were subseque ntly exposed to reconstructive surgery. Buccal and lingual full thickn ess flaps were elevated in the lower premolar regions. The exposed roo t surfaces of the experimental teeth were planed. A notch was placed i n the roots at the base of the defect. In one side of the mandible (Te st group), phosphoric acid gel was applied over the root surfaces for 15 s. The acid was removed by flushing the root surfaces with sterile saline. Subsequently, a gel of EMD was applied to cover all instrument ed root surfaces. Following gel application, a resorbable barrier memb rane was adjusted to cover the buccal and lingual entrances of the fur cation defect. The flaps were repositioned to cover the barrier and su tured. The contralateral premolar (Control group) received the same tr eatment, but acid etching was not performed and EMD was not applied pr ior to barrier installation. 4 months after reconstructive surgery, th e animals were sacrificed and biopsies from the P-3(3) regions harvest ed. The biopsies were placed in a fixative, demineralized in EDTA, deh ydrated and embedded in paraffin. 3 mesiodistal sections, representing the central portion of the furcation site, were selected for histolog ical analysis of the defect. The furcation defects of both the Test an d Control groups were clinically closed and mere found to harbor bone and periodontal ligament tissue which appeared to be in structural con tinuity with a newly formed root cementum. The relative amounts of min eralized bone, bone marrow and periodontal ligament tissue that had fo rmed were similar in the Test and the Control group. In the Test group , however, the cementum that had formed in the apical portion of the f urcation defect was different from the corresponding tissue in the cor onal portion, and also different from the cementum observed in the Con trol group. In the apical portion of the test defect a thin (12 mu m) acellular cementum had been laid down, while in the coronal portion a thick (32 mu m) cellular cementum, similar to the cementum found in th e Control group, could be observed. The current observation, hence, se ems to confirm that EMD when applied onto an instrumented and acid etc hed dentine surface may create an environment conducive for the format ion of acellular cementum.