THE EFFECT OF ANTIMICROBIAL THERAPY ON PERIIMPLANTITIS LESIONS - AN EXPERIMENTAL-STUDY IN THE DOG

The objective of the present study was to evaluate the effect of syste mic antibiotics and local debridement in the treatment of experimental ly induced periimplantitis lesions. 5 Labrador dogs, about 1-year old, were included in the study. In order to establish bilateral recipient sites for implants the mandibular right and left Ist molars, 4th and 3rd premolars were removed. 6 titanium fixtures (Branemark System(R) N obelpharma AB, Goteborg, Sweden) were installed and standard abutments were connected 3 months after fixture installation. Cotton floss liga tures were placed in a submarginal position around the neck of the abu tments and the animals were placed on a diet which allowed plaque accu mulation. After 6-8 weeks, when the tissue destruction amounted to abo ut 20% of the fixture length, the ligatures were removed. 1 month afte r ligature removal, an antibiotic regimen (amoxicillin and metronidazo le) was initiated and maintained for 3 weeks. In the left side of the mandible, buccal and lingual mucoperiosteal flaps were elevated, the g ranulation tissue within the bone craters adjacent to the implants was curetted, and the abutments were removed. The exposed outer surface, the internal part of the fixtures, as well as the abutments were treat ed with a detergent, delmopinol. The cleaned abutments were autoclaved , and connected to the cleaned fixtures. The mucoperiosteal flaps were replaced to their original position, adapted to the abutments and sut ured. A careful plaque control program was initiated for the left jaw quadrants. In the right side of the mandible no local treatment was gi ven to the fixtures and the abutments following ligature removal. Furt hermore, no plaque control was provided to the implant segments in the right jaws. After 4 months of healing block biopsies including one im plant with adjacent hard and soft tissue were harvested and prepared f or light microscopy. It was observed that systemic antimicrobial thera py, combined with implant cleaning, curettage of the bone defect and r egular plaque control resulted in (i) resolution of the periimplantiti s lesion, (ii) a significant recession of the marginal periimplant muc osa, and (iii) a minor additional apical shift of the base of the bone defect. In the untreated sites the plaque associated infiltrate remai ned and was in several sites examined in contact with the adjacent bon e tissue.