H U Luder1. 1. Institute of Oral Structural Biology, University of Zurich, Switzerland.
Abstract
BACKGROUND: The adult mandibular condyle is reported to be covered by fibrocartilage that develops from growth cartilage present earlier in life. Available data on the organization of condylar fibrocartilage are entirely descriptive or have been derived from young adult individuals. In order to examine the variability in normal appearance, condyles from a representative sample of adult humans were analyzed semiquantitatively. METHODS: With a light microscope, features of the superficial, intermediate, and deep tissue zones subjacent to small contiguous sectors of the articular surface were recorded. The distribution of each feature relative to the total surface was then calculated and respective data obtained from nine predetermined condylar regions and from males and females were compared using analysis of variance. RESULTS: The organization of the articular tissue varied significantly in the anteroposterior direction only. Unlike during growth, the superficial and deep zones in anterior and superior regions mostly contained fibrocartilage, although of markedly different appearance. Furthermore, the intermediate zone along about half of its anteroposterior extension lacked a distinctly visible layer, because the cell density was low and there was dense fibrous tissue or fibrocartilage similar to that of the superficial or deep zone, respectively. In these situations, zonation of the articular tissue was revealed only by the arrangement of collagen fibers. CONCLUSIONS: The appearance of adult condylar articular tissue, in addition to varying considerably within and between putative load-bearing and nonload-bearing regions, bears only a vague resemblance to the layered organization of the growing condyle. Current terminology that refers to that organization, therefore, is inappropriate. It is proposed to designate impartially the three articular tissue zones of the adult condyle as "superficial," "intermediate," and "deep."
BACKGROUND: The adult mandibular condyle is reported to be covered by fibrocartilage that develops from growth cartilage present earlier in life. Available data on the organization of condylar fibrocartilage are entirely descriptive or have been derived from young adult individuals. In order to examine the variability in normal appearance, condyles from a representative sample of adult humans were analyzed semiquantitatively. METHODS: With a light microscope, features of the superficial, intermediate, and deep tissue zones subjacent to small contiguous sectors of the articular surface were recorded. The distribution of each feature relative to the total surface was then calculated and respective data obtained from nine predetermined condylar regions and from males and females were compared using analysis of variance. RESULTS: The organization of the articular tissue varied significantly in the anteroposterior direction only. Unlike during growth, the superficial and deep zones in anterior and superior regions mostly contained fibrocartilage, although of markedly different appearance. Furthermore, the intermediate zone along about half of its anteroposterior extension lacked a distinctly visible layer, because the cell density was low and there was dense fibrous tissue or fibrocartilage similar to that of the superficial or deep zone, respectively. In these situations, zonation of the articular tissue was revealed only by the arrangement of collagen fibers. CONCLUSIONS: The appearance of adult condylar articular tissue, in addition to varying considerably within and between putative load-bearing and nonload-bearing regions, bears only a vague resemblance to the layered organization of the growing condyle. Current terminology that refers to that organization, therefore, is inappropriate. It is proposed to designate impartially the three articular tissue zones of the adult condyle as "superficial," "intermediate," and "deep."