The Effect of Age on the Mechanical Properties of the Periodontal Ligament in the Incisor Teeth of Growing Young Rats¹

Abstract

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.

Mechanical Strength and Viscoelastic Response of the Periodontal Ligament in Relation to Structure

“…In order to elucidate the tooth support mechanisms, Chiba's group systematically investigated the effects, on the mechanical properties of the PDL, of various experimental factors [4] such as periodontal disease [10, 22], hypofunction [18, 35, 36], orthodontic forces [37–39], treatment with inhibitors (lathyrogens) of collagen cross-linking and an inhibitor (hydrocortisone) of collagen degradation or turnover [8, 40–43], age [7, 17, 20, 44, 45], and root levels [19, 21]. They found that the mechanical properties were sensitive to both experimental alterations and to differences in the content, direction, and organisation of the collagen fibre components of the PDL.…”

Measurement of the Force Required to Extract the Mandibular First Molar from Its Socket in the Dissected Jaw of Growing Young Rats

“…The forces required to extract the rat mandibular incisor increased markedly with age from 4 to 24 weeks . However, stress values represented as load/unit area of the periodontal ligament of the rat mandibular incisor did not show age-related increases from 3 to 24 weeks of age [Yamane. 1990].…”

Mechanical Properties of the Periodontal Ligament in the Incisor Teeth of Rats from 6 to 24 Months of Age

“…The ultimate load required to extract the rat incisor from its socket increased gradually with age from 4 to 24 weeks [Chiba etal., 1980]. Asimilar tendency was also estimated from the load-deformation curves when the tooth was pushed out of its surrounding alveolar bone in sections of the mandibles of rats from 3 to 24 weeks of age [Yamane, 1990]. However, age-related changes were not appreciable in all mechanical measures estimated from the stress-strain curves in the latter experiment.…”

“…It has been suggested that increases in rat periodontal mechanical strength with age are related to those in the size of teeth and/or that area of the periodontal ligament facing cementum [Chiba et al, 1980;Yamane, 1990]. Furthermore, the qualitative and quantitative changes per unit area of the ligament are minor from 3 to 24 weeks of age [Yamane, 1990].…”