Soft tissue reactions to bioactive glass 13-93 combined with chitosan.

The aim of this study was to evaluate rabbit soft tissue reactions to bioactive glass 13-93 mesh by using a histological and immunohistochemical analysis. Bioactive glass (13-93) mesh fixed with 3 wt % chitosan was implanted into the dorsal subcutaneous space of New Zealand White rabbits (n=18) for six, 12, and 24 weeks, respectively. After 6 weeks the bioactive glass remnants were surrounded by foreign-body granuloma with eosinophilic granulocytes. After 12 and 24 weeks the implanted material was mainly absorbed, but, if any particles still remained the foreign-body reaction was notably milder. Yet, a mild chronic inflammatory infiltrate was present. Matrix metalloproteinase (MMP) -2, -3, -13 and tissue inhibitory protein (TIMP-1 and -2) expressions were studied by immunohistochemistry. MMP-3, -13, TIMP-1, and -2 positivity were detected throughout the follow-up period. MMP-2 positivity was only occasionally seen in the 24 week samples, which is constitutively expressed but is not related to inductive MMP-3 and -13 cascade. The presence of eosinophilic granulocytes in some of the samples raises the possibility of an allergic reaction to the materials. MMP-3 and -13 are suggested to participate in the host reaction to either bioactive glass or chitosan.

Tyrosine derived polycarbonate membrane is useful for guided bone regeneration in rabbit mandibular defects.

Standardized bilateral through-and-through defects (12x6 mm) were created extraorally in the mandibular angle of 18 New Zealand White rabbits. Animals were divided in to three groups (n=6) according to the intended healing time. On the left side, defects were covered with a poly(desaminotyrosyl-tyrosine-ethyl ester carbonate) (PDTE carbonate) membrane wrapped around the inferior border of the mandible and fixed with bioabsorbable sutures. On the right side, the defects were filled with a mesh made of bioactive glass 13-93 and 3 wt% chitosan. The defects were covered with the same membranes. Periosteal flap was sutured over the membrane. Radiographically, bone ingrowth was seen in all specimens at 12 weeks postoperatively. At 24 weeks, completely ossified area remained approximately at the same level as at 12 weeks, but the non-ossified area decreased to almost zero. However, the bioactive glass mesh did not improve the results. Nevertheless, enveloping the defect with PDTE carbonate membrane seemed to play a crucial role in new bone formation. Based on these results, we conclude that tyrosine polycarbonate is a promising new material for guided bone regeneration.