The effect of age on the mechanical properties of the periodontal ligament in the incisor teeth of growing young rats.

Mechanical properties of the periodontal ligament of the incisor have been examined by pushing the tooth out of its surrounding alveolar bone in sections of the mandibles of rats from 3 to 24 weeks of age. The maximum load, failure energy in shear and elastic stiffness estimated from the load-deformation curves, showed a tendency to increase with age from 3 to 12 weeks but the maximum deformation did not. Age-related changes were not appreciable in all mechanical measures estimated from the stress-strain curves. It is suggested that increases in the maximum load and elastic stiffness from the load-deformation curves with age are closely related to those in the size of teeth or in the area of the periodontal ligament facing cementum. It is also suggested that qualitative and quantitative changes in the supporting tissues or in the collagen fibres/unit area of the periodontal ligament are minor from 3 to 24 weeks of age in the rat mandibular incisor.