Experimental peri-implant mucositis in man

Objectives: The purpose of this study was to examine reactions of gingiva a nd peri-implant mucosa (PiM) to de novo plaque accumulation in humans. Material and Methods: Prior to the start of the study, which included 12 pa rtially edentulous subjects, a 3-week plaque control program was performed. Ethical approval was granted by the local ethics committee. On day 0, 2 so ft tissue biopsies were harvested, 1 from a tooth and 1 from an implant sit e in every subject. After 3 weeks of undisturbed plaque accumulation (day 2 1), 2 additional biopsies were obtained from the gingiva and PiM in each su bject. The tissue samples, each 4x4 mm in size, were snap frozen and prepar ed for immunohistochemical analysis. Results: The size of the infiltrate (ICT) in the day 0 biopsies, was about 0.03 mm(2) in both the gingiva and PiM. At the end of the plaque accumulati on period, the size of the lesion had significantly increased in both group s and occupied an area of 0.26 mm(2) in the gingiva and 0.14 mm(2) in PiM. In the biopsies presenting day 0, the proportions of the various cell popul ations examined were similar in the gingiva and in PiM. The tissue fraction s of almost all types of cells increased during the 3 weeks, but the mean c hange for each cell type was greater in the gingiva than in PiM. The CD3/CD 19 ratio decreased in the gingiva between day 0 and 21, but increased in PI M. Conclusion: The results of the present study indicated that plaque accumula tion induced an inflammatory response characterized by increased proportion s of T-and B-cells in the ICT of both the gingiva and the PiM. Although not statistically significant, the host response in the gingiva tended to be m ore pronounced than in the peri-implant mucosa.