Effect of Experimental Inhibition of Craniomaxillofacial Growth on the Rat Condyle

Abstract

I investigated effects of the inhibition of unilateral craniomaxillofacial growth on the condyle in 80 male Wistar rats. A spring appliance made of orthodontic wire was inserted in the left infraorbital fissure of the maxilla and occipital bone at 5 days of age, and the rats were sacrificed at ages 4, 6, 10 and 15 weeks. Effects on the condylar cartilage were examined by histological and histometric methods.
      The craniomaxillofacial complex and mandible shifted to the left in the experimental group. Thickness and chondrocyte density of each cartilage layer of the temporomandibular joint decreased with age in the control group and in the anterior region of the experimental group. Thickness of the intermediate and hypertrophic zones and the total thickness of all layers in the central region on the left side (shift side) were greater than those of the controls. Thickness of the hypertrophic zone and the total thickness of all layers in the posterior region on the right side (non-shift side) were greater than those in the controls. In the later stages, cartilage matrix metachromasia was clearly observed in the central region of the shift side and in the posterior region of the non-shift side.
      Sagittal inhibition of the craniomaxillofacial complex on the left side resulted in superior acceleration of condylar growth on the left. Since the craniomaxillofacial complex shifted to the left, posterior growth of the condyle was accelerated on the right side.