title: In-vitro mechanics of intrusive loading in porcine cheek teeth with intact and perforated root apices.
abstract: Cyclic intrusive loads were applied to deciduous cheek teeth and monitored by radiography in dissected mandibles in three successive states: (A) intact, (B) vertically bisected in a bucco-lingual plane, (C) with perforation of the apices by lateral drilling of the mandible subsequent to (B). Loading was in a compression cage in an Instron mechanical testing-machine utilizing cross-head speeds of 0.5 and 5 mm/min, leading to loading rates of approximately 2 and approximately 20 N/s. Peak loads were approximately 100 N, causing an intrusion of approximately 200 microns. Load/recovery curves for each tooth in the three states were recorded and the data treated assuming: (a) a simple shear on the periodontal ligament, (b) tensile loading on the fibres of the collagen fraction of the ligament alone. Treatment (b) gave the best agreement with published mechanical data on isolated mammalian periodontal ligament. The small effect of apicectomy on the mechanical behaviour indicates that a mobile fluid-like support mechanism is unlikely to operate for major loads in vitro and tensile support by the collagen fibres of the periodontal ligament is the most likely dominant mechanism.
mesh_terms: D000539:Alveolar Process / Q000502:physiology; D000818:Animals; D004548:Elasticity; D010513:Periodontal Ligament / Q000502:physiology*; D013314:Stress, Mechanical; D013552:Swine; D014092:Tooth Root / Q000293:injuries / Q000502:physiology*