Immunohistochemical analysis of blood vessels in peri-implant mucosa: a comparison between mini-incision flapless and flap surgeries in domestic pigs

Aim The aim of this experimental study is to compare the effect of mini-incision flapless versus flap technique of implant placement on the amount of vascular structures and blood vessel elements in peri-implant soft tissue, using immunohistochemical analysis. Method The experiment was conducted on five domestic pigs. Each animal received six implants in mandible according to the split-mouth design. On one randomly chosen jaw side, mini-incision flapless surgery was performed, whereas on the opposite jaw side, flap was raised. After 3 months of implant healing through submerged approach, the experimental animals were sacrificed and samples for immunohistochemical analyses were taken from the buccal side of peri-implant mucosa next to the neck of implants, from three levels. The study outcome was the presence of vascular structures and elements of the blood vessels in the peri-implant mucosa per microscopic field, estimated through ordinal scores from 0 to 2. Effects of surgical approach, site of implantation, and their interaction on vascular scores of peri-implant mucosa were assessed by Brunner and Langer nonparametric analysis of longitudinal data. Results Statistically significant effect of surgical approach on vascularity of peri-implant mucosa has been revealed in the second mucosal layer, where flapless approach provided higher vascularity compared with flap approach (P = 0.002). In the remaining two layers, surgical approach did not affect mucosal vascularity significantly (layer 1: P = 0.071; layer 3: P = 0.433). Conclusion The flapless surgical implant placement approach using mini-incision provides better vascularization of peri-implant mucosa after 3 months of healing compared with flap surgery.