Temporomandibular joint disc: a proposed histopathological degeneration grading score system

The purpose of this study was to draw up a TMJ disc histopathological score that is a semi-quantitative 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.

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.

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.

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.