Metric evaluation of partially displaced temporomandibular joint disc

The objective was to determine the quantitative relationship between the condyle and disc position in the glenoid fossa between two different slices of the same temporomandibular joints (TMJs) with partial anterior disc displacement (DD). The study was conducted on 40 patients with DD of TMJs (mean age, 35.5 years). The clinical diagnosis of DD was confirmed by magnetic resonance imaging. Joints from the patient groups were analyzed according to the laterality and depending on disc displacement (a total of 80 joints). Comparison was made between two different slices of 9 joints with partial DD with reduction: partial DD was analyzed in the representative centrolateral or centromedial parasagittal slice of the TMJ (TMJ partial DD--slice DD). The contralateral slice of the same joint was without DD (TMJ partial DD--slice NDD). The analysis also included 34 healthy joints without DD (TMJ NDD) of the same patients. The position of the condyle and disc was calculated using the Kurita et al. method on the parasagittal view of the TMJ. A statistically significant difference was recorded for different slices of the same TMJs with partial DD (TMJ partial DD--slice DD and TMJ partial DD--slice NDD) (p < 0.01), but no difference was found in condyle positions depending on the existence of partial DD (p > 0.05). The compared values between slice TMJ partial DD--slice NDD with the group of TMJ NDD showed no significant difference in either disc position or condyle position (p > 0.05). There were differences of disc position in various slices of the same joint with visually confirmed partial DD. The dorsocranial condyle position could not indicate partial anterior DD.