Abstract
To elucidate the mandibular bone mass changes due to occlusal and masticatory alterations in addition to aging, 66 Donryu male rats (30-74 weeks old) were divided into three groups, a control group (fed with a solid diet), a soft diet group (fed with a powder diet containing the same components as the solid one, from the 43rd week) and a molarless group (all molar were removed at 43 weeks and then fed with a powder diet).
The bone mineral densities (BMDs) were measured by quantitative methods using soft roentgenograms and image analyzing system, and the data were compared with each other. The results obtained are as follows.
1. The BMD of condyles in control increased with age to the 43rd week, and then decreased gradually. The BMD of the same area in soft diet and molarless groups decreased depending on age after the 47th week. There were significant decrease in the BMD of experimental groups (p<0.01).
2. The BMD of the attachment area of the masseter muscle in control increased with age to the 60th week, and then decreased. The BMD of the same area in the soft diet and molarless groups decreased depending on age after the 60th week. There were significant decrease in the BMD of the experimental groups (p<0.05).
3. The BMDs of condyles showed lower values in the experimental groups than in the control group at all ages.
These findings suggested that the bone remodeling in the condyle and the attachment of the masseter muscle in aged rats were considerably influenced by occlusal and masticatory alteration in addition to aging.
