IADR Abstract Archives
Biomechanics of Bruxism Determine the Sites of Severe TMJ Osteoarthritis.
Objectives: The objective of this study was to assess the osteoarthritis (OA) disease severity in a cohort of 47 temporomandibular joints (TMJs) using a validated scale for OA gross symptoms while noting the specific sites for profound disease severity on the donor condyle and fossa.
Methods: The donor population was approximately 50% males and 50% females and between the ages of 69-107 years old. The TMJs were removed from cadaveric skulls using classical dissection techniques and were disarticulated with reflection of the capsular ligaments. A disease severity score of Grade 0-4, representing absent to severe disease, was awarded to each specimen’s condyle and fossa by two blinded investigators who have demonstrated interrater reliability by evaluation using Krippendorff’s alpha (Kα).
Results: The mandibular fossa was significantly more pathological compared to the mandibular condyle in this population (*p=0.001). When the deepest focal lesions were qualitatively assessed for presentation and visual surface area coverage it was demonstrated that the mandibular fossa was more severely degenerated than the articular eminence in 58% of donors. In this subpopulation, 74% of the severe mandibular fossa pathology was seen on the deep articular surface opposed to the medial or lateral periphery of the fossa. When the articular eminence was the most severely degenerated region of the fossa, it was equivalently likely to see severe focal lesions on the lateral eminence (35%) or equally distributed across the entire eminence (35%).
Conclusions: In normal chewing, and to a greater degree in patients with bruxism, there are significant lateral, translational movements occurring in the upper joint compartment. Clenching, also seen with bruxism, amplifies pressure and potentially inflammation in the deepest regions of the mandibular fossa. In a population with such a high average disease severity score (3.4/4) for TMJ OA, it is understandable why deep and lateral fossa degeneration is a trend.
Methods: The donor population was approximately 50% males and 50% females and between the ages of 69-107 years old. The TMJs were removed from cadaveric skulls using classical dissection techniques and were disarticulated with reflection of the capsular ligaments. A disease severity score of Grade 0-4, representing absent to severe disease, was awarded to each specimen’s condyle and fossa by two blinded investigators who have demonstrated interrater reliability by evaluation using Krippendorff’s alpha (Kα).
Results: The mandibular fossa was significantly more pathological compared to the mandibular condyle in this population (*p=0.001). When the deepest focal lesions were qualitatively assessed for presentation and visual surface area coverage it was demonstrated that the mandibular fossa was more severely degenerated than the articular eminence in 58% of donors. In this subpopulation, 74% of the severe mandibular fossa pathology was seen on the deep articular surface opposed to the medial or lateral periphery of the fossa. When the articular eminence was the most severely degenerated region of the fossa, it was equivalently likely to see severe focal lesions on the lateral eminence (35%) or equally distributed across the entire eminence (35%).
Conclusions: In normal chewing, and to a greater degree in patients with bruxism, there are significant lateral, translational movements occurring in the upper joint compartment. Clenching, also seen with bruxism, amplifies pressure and potentially inflammation in the deepest regions of the mandibular fossa. In a population with such a high average disease severity score (3.4/4) for TMJ OA, it is understandable why deep and lateral fossa degeneration is a trend.