Faculty Bibliography

Surface microgeometry plays a role in tissue-implant surface interactions, but our understanding of its effects is incomplete. Substrate microgrooves strongly influence cells in vitro, as evidenced by contact guidance and cell alignment. We studied "dot" colonies of primary fibroblasts and bone marrow cells that were grown on titanium-coated, microgrooved polystyrene surfaces that we designed and produced. Rat tendon fibroblast and rat bone marrow colony growth and migration varied (p < 0.01) by microgroove dimension and slightly by cell type. We observed profoundly altered morphologies, reduced growth rates, and directional growth in colonies grown on microgrooved substrates, when compared with colonies grown on flat, control surfaces (p < 0.01). The cells in our colonies grown on microgrooved surfaces were well aligned and elongated in the direction parallel to the grooves and colonies. Our "dot" colony is an easily reproduced, easily measured and artificial explant model of tissue-implant interactions that better approximates in vivo implant responses than culturing isolated cells on biomaterials. Our results correlate well with in vivo studies of titanium dioxide-coated polystyrene, titanium, and titanium alloy implants with controlled microgeometries. Microgrooves and other surface features appear to directionally or spatially organize cells and matrix molecules in ways that contribute to improved stabilization and osseointegration of implants.

PURPOSE: The purpose of this study was to examine the crestal bone, connective tissue, and epithelial cell response to a laser microtextured collar compared with a machined collar, in the dog model. MATERIALS: Six mongrel dogs had mandibular premolars and first molars extracted and after healing replaced with BioLok implants 4 x 8 mm. Each dog had 3 control implants placed on one side of the mandible and 3 experimental, laser microtextured, implants placed contralaterally. After 3 months, 1 dog was killed. Bridges were placed on the implants of 4 of the dogs. The sixth dog served as a negative control for the duration of the experiment. Two of the dogs were killed 3 months after loading, of the dogs were killed 6 months after loading as was the negative (unloaded) control. Histology, electron microscopy, and histomorpho-metric analysis was done on histologic sections obtained from block sections of the mandible containing the implants. RESULTS: Initially the experimental implants showed greater bone attachment along the collar. With time the bone heights along the control and experimental collars were equivalent. However, the controls had more soft tissue downgrowth, greater osteoclastic activity, and increased saucerization compared with sites adjacent to experimental implants. There was closer adaptation of the bone to the laser microtextured collars. CONCLUSION: Use of tissue-engineered collars with microgrooving seems to promote bone and soft tissue attachment along the collar and facilitate development of a biological width.