The temporomandibular joint disc: Cellular, biochemical and molecular biological characterizations

Abstract

Session I: TMJ The Temporomandibular Joint Disc: Cellular, Biochemical and Molecular Biological Characterizations Regina Landesberg, DMD, MS, Univ. of Rochester, Depts. of Orthopaedics and Oral and Maxillofacial Surgery, Box 665, Rochester, NY 14642 (Rosier, R.N., Chomczynski, P., Sacchi, N.: Single-step method isolation by acid buanidinium theocyanage-phenol-chloroform extraction. Analytical Biothem, 1987 Vol 162:156-159 Funding provided by the NIH Felter, M.E., Puzas, J.E.) The limited knowledge of the composition and cellular dynamics of normal and diseased temporomandibular joint (TMJ) disc tissue has restricted our ability to understand underlying disease processes. Our goal in this study was to apply cellular, biochemical and molecular techniques to the characterization of the cellular activity and composition of this tissue. For cell isolation, bovine TMJ discs were cleaned of adherent tissue, minced into 1 mm3 pieces and enzymatitally digested. Cells were placed into primary culture and assayed for rates of proliferation, alkaline phosphatase activity, collagen and non-collagen protein synthesis, DNA content and proteoglycan production. Messenger RNA levels for different collagen types (I, II and III) and autocrine growth factors (transforming growth factor beta, TGF B) were determined by cDNA hybridization to total mRNA extracts. The effect of transforming growth factor beta and prostaglandin E, on cellular proliferation was also determined. The disc tissue used for collagen typing was extracted by acetic acid/pepsin digestion of Polytron homogenates. The typing techniques included polycrylamide gel electrophoresis, Western blot analysis and cyanogen bromide clevage product analysis. The TMJ disc cells 1) proliferate rapidly in primary culture with approximately 10% of the cells participating in DNA synthesis, 2) demonstrate very low levels of alkaline phosphatase activity as compared to chondrocytes and bone cells, 3) produce approximately 12% of total protein as collagen, 4) synthesize a mixture of collagen types consisting of predominantly type I colla- gen, 5) synthesize substantial amounts of proteoglycan, 6) respond to TGF B, but not prostoglandin EZ, with an increase in proliferation rate, 7) contain high levels of collagen message transcripts and low but demonstrable levels of TGF B transcripts and 8) maintain a polygonal morphology in sub-confluent primary culture. Our results should allow us to begin to understand the composition, synthetic activity and regulation in TMJ disease. Such information will ultimately be applied to human samples and will be valuable for directing treat- ment modalities and rational replacement therapies of the TMJ disc. References LongTerm Performance of Temporalis Muscle Flap When Used as a Disc Replacement William Purdy, DDS, The Ohio State Univ., Oral and Maxillofacial Surgery, 305 West 12th Ave., Columbus, OH 43210 (Feinberg, S., Larsen, P.) When removal of the articular disc is required in the surgical management of internal derangement of the temporomandibular joint, a substitute interpositional ma- terial is often used. Most alloplastic materials have significant shortcomings, and therefore, most contempo- rary surgeons use some type of autogenous material such as dermis. We have reported on the use of a muscle flap from the temporalis muscle which is pedicled from the coronoid process and is sutured posteriorly to the retrodis- cal tissue. The purpose of the abstract is to present long-term (two year) follow up on the first 9 patients upon whom this operation was performed. All 9 patients presented with chief complaint of severe pain and limitation of function. Preoperative maximum incisal opening ranged from 5mm to 33mm with an average of 20mm. Five of the nine patients had had previous surgery which included procedures such as plications, and teflon-proplast implants. Three patients had disc subluxation without reduction (closed lock). The temporalis muscle flap procedure was decided upon when previously placed implants needed to be removed or when the disc was so severely damaged that it needed removal. The surgical procedure has been described in detail elsewhere, but consists of an anteriorly based flap which is passed anteriorly and inferiorly to the root of the zygo- matic arch into the area of the joint. The posterior aspect of the muscle flap is sutured to the retrodiscal tissue. Of the 9 patients in this study, 3 had bilateral muscle flap procedures and 6 unilateral, for a total of 12 joints. On long-term follow-up, all patients have a dramatic decrease in their pain, and an overall generalized improve- ment in their function. The maximum incisal opening for the entire group of patients increased from 20mm to 35mm. Five patients had preoperative opening of less than 20mm (14mm Avg) and increased their opening to an average of 36mm, for an average increase of 160%. No patients have required re-operation during the follow-up Webber, R.J., Zitaglio, T. and Hough, A.J.: Serum-free culture of period. rabbit meniscal fibrochondrocytes: Proliferative Response. J Ortho In summary, we believe that the temporalis muscle flap Research, 1988 Vol. 6: 13-23 procedure is a viable technique for routine use as a disc