A theoretical model of loading and eminence development of the postnatal human temporomandibular joint.

The objectives of the present study were to characterize the loading of the immature TMJ, and to develop a theoretical model to explain the relationship between joint loading and development of the eminence of the human TMJ. The osteological remains of forty individuals, ages ranging from birth to twenty years, were used to provide metric coordinates of the three-dimensional relationships of the anatomy of the biting apparatus. The data were used, in a numerical model of TMJ loading (Smith et al., 1986), to calculate the magnitudes and directions of condylar loading. The following conclusions were drawn: (i) static equilibrium cannot be satisfied unless the immature TMJ is loaded; (ii) in the neonate, the direction of condylar loading is approximately vertical but, as the child matures, the angle of condylar loading becomes more oblique; and (iii) evidence is given in support of the hypothesis that early development of the eminence is consequent upon the stimulation of bone growth by the appropriate position and timing of loading of the immature condyle on the temporal component of the joint.