Meeting Abstract

10.9  Sunday, Jan. 4  XROMM analysis of mastication in miniature pigs METZGER, KA*; BAIER , DB; LIN, A; HARPER, CJ; HERRING , SW; BRAINERD, EL; Touro University College of Medicine; Brown University; Brown University; Brown University; University of Washington; Brown University Keith.Metzger@touro.edu

XROMM (X-ray Reconstruction of Moving Morphology) is a newly developed technique for visualization and analysis of 3D skeletal kinematics. In XROMM, accurate animations of skeletal movement are generated by combining 3D morphological data from CT scans with biplanar videofluoroscopy. The goals of this study are to: (1) assess precision of radiopaque marker-based XROMM under typical in vivo experimental conditions, and (2) compare results of XROMM analysis of the kinematics of minipig mastication with previously published studies. Precision of XROMM is assessed through analysis of inter-marker distances between pairs of markers implanted in the same bone and recorded under typical experimental conditions at 250 Hz. The mean standard deviation of inter-marker distance for 13 chewing sequences is 0.084 mm, and there is no significant difference between manual and automatic tracking methods for marker centroids (p=0.82). Results of the XROMM analysis of minipig mastication are consistent with previous studies (e.g. Herring, 1976, Arch. Oral. Biol. 21: 473), including bilateral grinding and frequent reversal of grinding direction with each stroke. The 3D rigid body kinematics of the mandible confirm the importance of lateral grinding, and show for the first time that grinding results primarily from rotation of the mandible about a dorsoventrally oriented axis, with little contribution from lateral translation of the whole jaw. Substantial dorsoventral and rostrocaudal translations were found, resulting from jaw protrusion and retrusion. Rotation about a rostrocaudally oriented axis was negligible, likely due to soft tissue constraints and low amounts of tensile strain at the TMJ.