Histological study and evaluation of cytocompatibility of collagenous matrix derived from xenogeneic dermis used for gingival grafting

Background

Recently, porcine acellular dermal matrix has become an alternative to connective tissue autografts in periodontal surgery. For the experimental purpose of using an alternative material to autologous connective tissue we selected a case of keratinized gingival augmentation. The expected results had been disappointing, which led us to ask the problem of the evolution in situ of this matrix and the reality of its bio-integration. We investigated in vivo human biopsy taken from patient .

Aim/Hypothesis

The use of acellular dermal matrices has recently been proposed, for filling the bone defect, and avoiding the trauma induced by autogenous connective tissue removal. We present a clinical case that was treated by guided tissue regeneration using this membrane. 11 months after the graft, the regenerated site was satisfactory in volume, but the gingiva exhibited atypical redness. To prevent a future peri-implant complication, a biopsy was performed to histologically determine the state of the graft.

Material and Methods

Clinical examination of a 35-year-old man, present for the restoration of his first left upper premolar non-smoker, no general health problems, revealed the presence of a thin periodontium associated with a reduced amount of keratinized gingiva in height and thickness. An implant has been installed to replace the extracted tooth. And to compensate the bone loss, a xenogenic membrane with a thickness varying from 1.7 to 2 mm cut and prepared according to the implanted site was put in place and fixed by implant screw. At 2 months postoperatively, a satisfactory result clinically, with persistent redness of the gingiva at the surgical site. Concomitantly with the placement of the healing screw, a biopsy was performed- a small 3 mm fragment at the graft area was removed, and fixed in 4% formaldehyde and sent for pathology examination. A prosthesis was made and sealed 15 days later.

Results

Biopsy was performed at 11 weeks. The borderline between ADM and gingival connective tissue was very distinct. Anatomo-pathological examination (hematoxylin eosin staining) showed the presence of inflammatory cells, plasma cells, lymphocytes and macrophages in the gingival connective tissue. This is comparable to an inflammatory reaction in response to the presence of a foreign body. Within the ulceration, structures stained in red are identified that may be xenogenic membrane residues, as well as many elongated cells reminiscent of fibroblasts. In the ulceration, there are numerous giant cells with foreign bodies forming a granuloma. The blood vessels, which come from both flap and periosteum, have been observed penetrating the peripheral portion of the ADM+ they are well defined, signing a vascular neogenesis. Newly formed collagen fibers are present. Very dense collagenic bundles suggest fibrotic tissue.

Conclusion and Clinical Implications

In this case presentation the redness persistence may be related to chronic inflammation. infiltration, with a multinucleate giant cells, the function of this type of reaction is the difficulty to eliminate the material by phagocytosis or enzymatic destruction. The presence of giant cells and the persistence of clinical redness may be the cause of poor integration of this material. The presence of a fibrotic tissues is not physiologic. Larger and longer-term studies will support our conclusions