QUANTITATIVE ASSESSMENT OF TEMPOROMANDIBULAR-JOINT DISK STATUS

The purpose of this study was to quantify temporomandibular joint disk -slice information produced by magnetic resonance imaging by means of a stepwise discriminant analysis. One hundred ninety-four adolescents consented to magnetic resonance imaging evaluation of their temporoman dibular joints. Sagittal magnetic resonance imaging slices of each joi nt were assigned to one of six subjective categories of disk position by an experienced maxillofacial radiologist. Standardized reference pl anes transferred to each magnetic resonance image from corresponding l ateral cephalometric radiographics facilitated the measurement of disk length and disk displacement and the computation of ratio values of t hese measurements. Discriminant analysis revealed that all three quant itative variables were descriptive and discriminant for grouping slice data into pre-established subjective categories. Cross-validation and misclassification error calculations showed a 69.3% agreement between subjective and discriminant classification. Therefore quantification of disk displacement can be used in place of subjective evaluation. In addition,discriminant analysis disclosed a reduction in disk length a ssociated with increased severity of disk displacement.