Histologic Changes in Rabbit Temporo Mandibular Joint Following Local Injection of Recombinant-Bone Morphogenetic Protein-2 (rBMP2) during Mandibular Advancement by Bite Jumper

Mandibular deficiency is one of the most common malocclusions that is treated with functional appliances during growth periods. The aim of this study was to evaluate the histologic changes of the single local injection of rBMP2 in combination with bite jumper therapy in a rabbit model TMJ.

Eighteen 8-week old Albino New Zealand white male rabbits were divided into three groups: The first group served as control and in the second and third groups rBMP2 and normal saline were injected respectively. The second and third groups had bite jumper appliance. After 8-weeks of bite jumper therapy, in the second group 12.5gr rBMP2 powder plus 2.5cc normal saline and in the third group only 2.5 cc normal saline was injected in the TMJs on both sides. After 16-weeks of treatment, the animals were sacrificed and the joints were examined histologically.

The rBMP2 group showed greater cartilage cells and maximum condylar cartilage thickness (in the form of cartilage hyperplasia) than control and normal saline groups. The control group had the lowest disc deformity histologically and the rBMP2 group showed lower disc deformity than normal saline group.

rBMP2 is able to accelerate condylar cartilage growth in the form of cartilage hyperplasia.