Comparison of proliferation, apoptosis and expression of syndecan-1 and α-SMA in edentulous ridge oral mucosa of successful and early failed submerged dental implants--An immunohistochemical study.

Aims: Pathogenic mechanisms involved in early submerged implant failure are poorly understood. In this study we immunohistochemically analyse differences in proliferation, apoptosis and inflammation in edentulous ridge oral mucosa (ERM) of successful and early failed submerged implants.

Materials And Methods: 30 samples of ERM covering successful and early failed submerged implants were obtained at the end of osseointegration period along with control samples of healthy ERM. Sections were stained with Ki-67 (proliferation), caspase-3 (apoptosis) and syndecan-1 (epithelial marker). Percentage of positive cells was analysed by Kruskal-Wallis test and Dunn's post hoc test. Co-localization of Ki-67 and caspase-3 with α-SMA, CD68 and TGF-β was done by double immunofluorescence.

Results: There was no significant difference in number of Ki-67 positive cells within surface epithelium (SE) in all groups. Proliferation was significantly higher in underlying connective tissue (UCT) of ERM of early failed submerged implants (26%) compared to ERM of successful submerged implants (3%) and controls (4%). More apoptotic cells appeared in UCT of early failed submerged implants (8%) compared to UCT of successful submerged implants (4%) and UCT of control ERM (3%). Co-localization of Ki-67 and α-SMA in ERM of early failed submerged implants disclosed proliferating fibroblasts and pericytes of blood vessels. Macrophages and cells expressing TGF-β appeared in UCT of failed implants. Expression of syndecan-1 was significantly weaker in SE of early failed submerged implants.

Conclusions: Imbalance between proliferation and apoptosis, changes in syndecan-1 expression and inflammation are histopathological features of ERM of early failed submerged implants.