Abstract
To examine the bone mineral changes on the human mandibular condyle during development of the child,100 human dry skulls classified according to Hellman's dental age were selected from the collection held by the Department of Pediatric Dentistry of Meikai University, School of Dentistry. In order to evaluate the bone mineral density of the cortical and trabecular bone, frontal and lateral Xray images were obtained from the mandibular condyle, attaching an aluminum step-wedge to the film to give a reference image. Optical bone mineral density was scanned at the point of constriction of the condylar neck using a microdensitometer PDS-15 (Konishiroku Photo Ind Co., Ltd) The effective slit width was 10μm, with an aperture of 50×500μm2; the specimens were traversed at a speed of 0.2 mm/sec. The bone mineral density of the cortical bone was measured from the true profile plot by conversion the thickness of aluminum expressed as mm Al eqs. The mineral density of the trabecular bone was obtained from a power spectrum profile and it was then calculated to square centimeters.
The cortical and trabecular bone of the condylar neck showed different patterns of mineral density. Cortical bone resembled the Scammon growth curve for general somatic tissues during two period of increase; initial (IA-II A) and final (IVA-VA), with a middle period of small increases (IIC-III C). The bone matrix showed the highest period of increase during the initial stages (IA-IIA), followed a period of small increases.
This study indicates th at the trabecular bone tends to show changes in mineralization much earlier than the cortical bone. Supporting trabecular patterns need to be adapted to transmit and distribute mastication loading, while, the cortical bone mineralization is principally influenced by general growth.
