the effect of local injection of the human growth hormone on the mandibular condyle growth in rabbit

background: the aim of this study was to evaluate the effect of local injection of human growth hormone (gh) in stimulating cartilage and bone formation in a rabbit model of temporomandibular joint (tmj). materials and methods: in an experimental animal study, 16 male albino new zealand white rabbits aged 12 weeks were divided into two groups: in the fi rst group (7 rabbits) 2 mg/kg/1 ml human gh and in the control group (9 rabbits) 1 ml normal saline was administered locally in both mandibular condyles. injections were employed under sedation and by single experienced person. injections were made for 6 times with 3 injections a week in the all test and control samples. rabbits were sacrifi ed at the 20th day from the beginning of study and tmjs were histologically examined. anova (two-sided) with dunnett post hoc test was used to compare data of bone and cartridge thickness while chi-square test was used to analyze hyperplasia and disk deformity data. p < 0.05 was considered as signifi cant. results: cartilage layer thickness was greater in the gh-treated (0.413 ± 0.132) than the control group (0.287 ± 0.098) (p value = 0.02). although bone thickness and condylar cartilage hyperplasia were greater in the gh-treated group, these differences were not statistically signifi cant (p value = 0.189 and 0.083, respectively). there was no statistically signifi cant difference between two groups regarding the disc deformity (p value = 0.46). conclusion: local injection of human gh in the tmj is able to accelerate growth activity of condylar cartilage in rabbit. key words: growth, human growth hormone, mandibular condyle, rabbits