Temporomandibular joint disc; a proposed histopathological degeneration grading score system

Abstract

Summary. Aims: The purpose of this study was to draw up a TMJ disc histopathological score that is a semiquantitative transcription of the entire spectrum of TMJ disc degenerative diseases related to changes in disc tissue, and then validate the proposed grading, in order to contribute to a standardized histopathological diagnosis. Methods: Sections from sixty two temporomandibular joint disc specimens affected by tissue degenerative changes and stained with Hematoxylin & Eosin (H&E) were collected from among those found in the archives of the Department of Dentistry at Catania University. Specimens, included anterior, intermediate and posterior disc bands. Based on a literature search regarding the most frequent histopathological changes detected in TMJ disc tissue a grading score was designed. This score takes into account pathological disc tissue transformation i.e. collagen bundles, non-specific degenerative changes and the presence of blood vessels. This grading system results in a score ranging from 0 up to 8 for heavily degenerated disc tissue. Two observers performed the assessment of the TMJ disc H&E stained sections. Each specimen was scored twice by each observer after a minimum interval of 1 week. Results: The average TMJ disc degeneration score of the TMJ disc sample was 3.89±1.37. There was an almost perfect agreement, between the two observers, and degeneration scores from the two observers were highly correlated. Conclusions: The introduction of this validated degeneration score system may be of major importance for future research and collaboration between different centers in order to improve knowledge in TMJ disc histopathology.