Selective inhibition of condylar growth in the rabbit mandible using intra-articular papain

The purpose of this study was to clarify the relative importance of the condyle in mandibular growth. Activated papain, a protease which inhibits endochondral growth, was injected for 4 weeks into the left temporomandibular joints of growing rabbits. Histologic and morphologic changes were evaluated microscopically and by measurement of dried skulls and serial cephalometric radiographs. The injected condyles showed a rapid but temporary depletion of the cartilage matrix. Repeated injections produced severe arthritic changes in some cases. The papain caused a significant decrease in vertical ramal growth. Mandibular length was unaffected. The unilateral injections also produced vertical asymmetry characterized by a canting of the mandibular plane superiorly toward the injected side. It was concluded that, in the rabbit, condylar growth is essential for normal vertical growth of the ramus but has little influence on the length of the mandible.