Histological and immunohistochemical analysis of initial and early subepithelial connective tissue attachment at chemically modified and conventional SLA®titanium implants. A pilot study in dogs

The aim of the present pilot study was to histologically/immunohistochemically investigate initial and early subepithelial connective tissue attachment at transmucosal parts of modified (mod) and conventional sandblasted, large grit and acid-etched (SLA) titanium implants. Implantation of modSLA and SLA implants was performed bilaterally in both the mandible and maxilla of four beagle dogs. The implants were submerged to prevent bacterial contamination. The animals were killed after 1, 4, 7 and 14 days. Peri-implant tissue reactions were assessed histologically (Masson Goldner Trichrome stain-MG) and immunohistochemically (IH) using monoclonal antibodies to fibronectin (FN) and proliferating cell nuclear antigen (PCNA). The surgical procedure of implant submerging resulted in the formation of an artificial gap in the transmucosal area of both types of implants. After 14 days of healing, MG stain revealed the formation of well-organized collagen fibres and numerous blood vessels in a newly formed loose connective tissue zone adjacent to modSLA. While some fibres were oriented in a parallel direction, others have started to extend and attach partially perpendicular to the implant surface. In contrast, SLA implants appeared to be clearly separated by a dense connective tissue zone with parallel-running collagen fibres and rare blood vessel formation. First signs of a positive FN and PCNA staining adjacent to both implant surfaces were observed at day 4. Within the limits of a pilot study, it might be concluded that modSLA titanium surfaces might possess the potential to promote subepithelial connective tissue attachment at the transmucosal part of the implant.