Soft tissue response to plaque formation at different implant systems. A comparative study in the dog.

The aim of the present experiment was to study the location and composition of plaque associated lesions in the mucosa adjacent to implant systems that differed with respect to both geometry and dimension. At day 0 extraction of the mandibular premolars were performed. After a healing period of 3 months, fixtures of the Astra Tech Implants, Dental System, the Brånemark System and the ITI Dental Implant System were installed. In each mandibular quadrant 1 fixture of each implant system was installed in a randomized order. A period of plaque control was initiated. Following another 3 months of healing, abutment connection was performed in the 2-stage systems (the Astra Tech Implants, Dental System and the Brånemark System). After 1 month, the plaque control measures were abandoned and plaque formation was allowed for 5 months. The animals were killed and biopsies representing each implant region obtained. The tissue samples were prepared for light microscopy and exposed to histometric and morphometric measurements. The present study demonstrated that plaque formation resulted in the establishment of an ICT lateral to a pocket epithelium. The lesion was found to be similar regarding extension and composition in the peri-implant mucosa of the 3 implant systems tested. The vertical extension of the ICT was in all systems within 91-99% of the vertical dimension of the junctional epithelium. The marginal bone level, measured from the abutment/fixture (PS) border, did not differ between the three systems.