Histologic investigation of gingival epithelium implantation and the nonincision placement of miniscrews.

Purpose: This study investigated whether the nonincision placement of miniscrews could lead to ectopic implantation of epithelium at the bone-implant interface and, if so, whether the epithelial cells could survive. The fate of grafted epithelial cells was also investigated.

Materials And Methods: Ten healthy male beagle dogs were included in the study and were divided into three groups. Group 1 dogs (n = 3) were implanted with miniscrews without any other procedures. In group 2, epithelial cells were collected, infected by adeno-associated virus-2 containing green fluorescent protein (GFP), and injected into pilot holes drilled before miniscrew implantation in three dogs, and one dog was injected with epithelial cells as a negative control. In group 3, tiny gingival tissue pieces were injected into pilot holes drilled before miniscrew implantation. In group 1, hematoxylin-eosin and fluorescent immunohistochemical (IHC) staining of cytokeratin were performed on both undecalcified and decalcified slices. In groups 2 and 3, IHC staining of cytokeratin and apoptotic testing were performed.

Results: No ectopically implanted epithelial cells were found at the bone-implant interface of the miniscrews in group 1. In group 2, fluorescence emitted by cytokeratin antibody and by GFP was observed in specimens at 0 days, had decreased by 3 days, and had disappeared by 7 days. In group 3, areas of fluorescent cytokeratin-positive tissues were much smaller at 7 days than at 0 days, and none were found at 28 days. In groups 2 and 3, there were many apoptotic epithelial cells at the bone-implant interface at 3 days and 7 days, respectively.

Conclusion: There was little possibility of implantation of epithelium into alveolar bone though placement of miniscrews with a nonincision procedure. Furthermore, even when epithelial cells or tissue was ectopically implanted, it was soon cleared through an apoptotic process.