Histological analysis of regeneration of temporomandibular joint discs in rabbits by using a reconstituted collagen template.

The aim of this study was to design a biodegradable implant, in the form of a reconstituted collagen template in order to promote and support regeneration of the temporomandibular joint disc. Bovine collagen (Major Type I) was pepsinized, reduced by beta-mercaptoethanol, and reconstituted by glutaraldehyde. The reconstitution of the collagen increased the resistance to biological degradation by collagenase, optimized the pore size and possessed maximum biological activity for tissue regeneration. Forty-four New Zealand rabbits underwent either sham surgical procedures or partial temporomandibular joint discectomy. In animals that underwent partial discectomy, the discs were replaced by either reconstituted collagen templates or subdermal grafts. Some of the surgerized animals did not receive any type of implant or disc substitute. Gross and histological examination of the surgerized temporomandibular joints was carried out at 1-, 2-, and 3-month intervals after surgery on the selected groups of animals. Marked arthritic changes were observed after 3 months in the partially discectomized joints without implantation. In contrast, the discs, which received a reconstituted collagen template or subdermal graft exhibited regeneration and nearly normal morpology. No foreign body response was observed in experimental groups 3 months after implantation. This study demonstrated that the reconstituted collagen did as well as subdermal grafts in supporting and facilitating regeneration of the disc and the former was found to have some advantages over the latter.

MRI and histology of collagen template disc implantation and regeneration in rabbit temporomandibular joint: preliminary report.

INTRODUCTION: We aimed to evaluate regeneration of injured temporomandibular joint (TMJ) discs following reconstituted collagen template implantation in rabbits using contrast-enhanced magnetic resonance imaging (MRI) and to correlate these findings with histology. METHODS: Twenty-four adult rabbits were divided into five groups: group A, partial discectomy without implantation (n = 6); group B, partial discectomy with collagen template implantation (n = 6); group C, partial discectomy with subdermal graft implantation (n = 6); group D, sham operation (n = 4); and group E, control (n = 2). All rabbits received baseline MRI scans before surgery and follow-up MRI studies at 3 months after surgery. All rabbits were sacrificed for histologic analysis after the follow-up MRI. RESULTS: In group A, follow-up MRI showed marked joint effusion in all six injured TMJs, which was accompanied by bony erosion at the tympanic fossa and mandibular condyle. In group B, MRI showed a homogenous low signal intensity in five of six discs, suggestive of regeneration. One disc showed higher signal intensity at its lateral portion than that of the original disc, indicating partial regeneration. MRI of group C depicted a low signal intensity, bandlike regenerative structure in four of the six discs. One disc with partial regeneration demonstrated relatively high signal intensity. The disc in the sixth animal of this group showed no evidence of regeneration. All of the MRI findings were in agreement with the histologic findings. CONCLUSION: TMJ discs can regenerate following implantation of a reconstituted collagen template in discectomied rabbits. Contrast-enhanced MRI can be used to monitor and determine the degree of disc regeneration.