Temporomandibular joint condyle changes after surgically induced non-reducing disk displacement in rabbits: a macroscopic and microscopic study

Experimentally induced displacement of the temporomandibular joint (TMJ) di sk has previously been shop to induce shortening of the mandibular ramus on the ipsilateral side. The aim of this investigation was to reveal whether this shortening develops due to primary influence on condyle growth or by s econdary loss of condyle mass due to degenerative tissue breakdown. Disk di splacement was created in the right TMJ in seven 3-month-old rabbits, the p osterior disk attachment kept intact. Seven rabbits underwent surgical open ing of the TMJ without disk intervention. Seven additional animals served a s references. After a 3-month experimental period, the animals were sacrifi ced. Previous analysis revealed shortening of mandibular height and length caused by ipsilateral TMJ disk displacement. The condyles were examined mac roscopically and by histologic sectioning or scanning electron microscopy. All condyles were covered with smooth articulating soft tissue and without visible signs of degenerative changes. Four condyles from joints with disk displacement demonstrated substantial regressive remodeling resulting in a change of condyle shape with forward/downward rotation of an enlarged artic ulating surface. It was concluded that TMJ disk displacement in a growing i ndividual can induce reduction of mandibular height and length before a sta ge where visible osteoarthrotic changes develop. It implies a primary adver se effect on condyle growth.