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Tractional Forces on Porcine Temporomandibular Joint Discs

¹ University of Missouri-Kansas City, School of Dentistry, Departments of Orthodontics & Dentofacial Orthopedics and Oral Biology, 650 East 25^th St., Kansas City, MO 64108-2784, USA;
² University of Nebraska Medical Center (UNMC), College of Dentistry, Departments of Adult Restorative Dentistry and Oral Biology, P.O. Box 83740, Lincoln, NE 68583-0740, USA; and
³ University of Nebraska, Department of Statistics, 340 Hardin Hall North, Lincoln, NE 68583-0963, USA

Correspondence: ^* nickeljc{at}umkc.edu

Tractional forces on the temporomandibular joint (TMJ) disc predispose tissue fatigue. This study tested the hypotheses that tractional forces: (1) increased with stress-field velocity (V) and aspect ratio (AR, contact area diameter/cartilage thickness), and compressive strain (); and (2) varied depending on cartilage thickness. Porcine TMJ discs (n = 187) received a 10-N vertical static load via an acrylic indenter for 1, 5, 10, 30, or 60 sec, followed by movement. Physical data were recorded and analyzed by quadratic regression relations and a likelihood ratio test. Results showed non-linear increases in tractional forces that were positively correlated with increased V, AR, and when the stress-field moved onto relatively thicker (R² = 0.83) and thinner cartilage (R² = 0.86). When V was > 27 mm/sec and AR·³, was > 0.09, tractional forces were significantly higher ( 12% of peak) when the stress-field moved onto thicker cartilage. Stress-field dynamic mechanics and cartilage thickness significantly affected TMJ disc tractional forces.

Key Words: TMJ • cartilage • traction • velocity • strain

Abbreviations: LVDT = linear voltage differential transformer • PBS = phosphate-buffered physiological saline solution • TMJ = temporomandibular joint • V = velocity • AR = aspect ratio • = compressive strain • UNMC = University of Nebraska Medical Center • µ_T = tractional coefficient • µ_S = static coefficient of friction

Journal of Dental Research, Vol. 88, No. 8, 736-740 (2009)
DOI: 10.1177/0022034509340161


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