Histologic and Ultrastructural Findings of Gingival Circular Ligament Surrounding Osseointegrated Nonsubmerged Loaded Titanium Implants

Eight nonsubmerged titanium implant screws were placed in monkey maxillary bone, restored 1 month after surgery, and kept under occlusal forces for 14 months. Block biopsy specimens were processed for light and electron microscopy. In all samples, the implant surface appeared integrated to both hard and soft peri-implant tissues. The supracrestal peri-implant connective tissue included densely packed collagen fibers free of inflammatory cells. The fibers originated from the alveolar bone crest, radicular cement of adjacent teeth, and gingival mucosa, and migrated towards the implant neck. Near to the implant surface, the fibers merged together and constituted a circular ligament. Thin histologic sections of the circular ligament showed collagen fibrils with diameters similar to those of the ligaments of natural teeth. Moreover, histochemical observations disclosed that the fibrils near the metal surface were immersed in a matrix containing highly sulfated proteoglycans. Keywords: gingival connective tissue, histochemistry, SEM, TEM, titanium implants