Objective      To study the expression of IGF-1 in bony class Ⅲ malocclusion patients and its relationship with growth of mandible.       Methods      Twenty-four bony class Ⅲ malocclusion patients and 27 bony class Ⅰ malocclusion patients were included in this study. Expression of IGF-1 in mandible tissue was detected by RT-PCR and ELISA

respectively.       Results      RT-PCR showed that the expression level of IGF-1 mRNA was significantly higher in bony class Ⅲ malocclusion patients than in bony class Ⅰ malocclusion patients (5.541 0±2.044 7 μg/μl vs 1.282 1±0.273 1 μg/μl

P0.05) . The regression factor was 0.998

which was calculated according to the correlation curve for IGF-1 optical density value and its concentration. ELISA showed that the expression level of IGF-1 protein was significantly higher in bony class malocclusion patients than in bony class Ⅰ malocclusion patients (84.125 9±29.294 7 ng/L vs 22.406 4±4.931 2 ng/L

P0.05).       Conclusion      The more the mandible grows

the higher the expression level of IGF-1 is

which indicates that IGF-1 plays an important role in growth of mandible condyloid cartilage.