Effect of Altered Mastication on the Osteogenesis of Condylar Cartilage

Objectives: To analyze the histomorphometry differences of condylar subchondral bone under altered masticatory loading, and to study the mechanism of masticatory loading on condylar development in growing rabbits.
Methods: sixteen 15-day-old rabbits were randomly divided into two groups and fed different kinds of food, such as solid diet (n=8) and soft diet (n=8). ALL the growing rabbits were weaned at day 14 (28-day-old). Tetracycline (50mg/kg), calcein (20mg/kg) and alizarin red (90mg/kg) were given intramuscularly on the day 14, 19 and 24. One day after the third labeling, the rabbits were sacrificed. The specimens of condyles were embedded in methylmethacrylate. Undecalcified hard tissue slicings (20mm) were then made and observed with a fluorescence microscope. We measured the thickness of the subchondral bone and the histomorphometry parameters of the condyle in two groups and did statistical analysis.
Results: No significant body weight differences were observed between solid diet groups and soft diet groups (P>0.05). The statistical analysis showed that there was significant difference in the subchondral bone thickness, percent trabecular area, trabecular perimeter, trabecular number, trabecular thickness and trabecular separation in the two groups (P<0.05). The solid diet groups exceeded those of the soft diet groups except trabecular separation. The mineral appositeion rate of solid diet groups
[ (3.25±0.02)μm / d ] was higher than soft diet groups [ (2.37±0.02)μm / d ].

Conclusions: A appropriate masticatory loading may promote the osteogenesis of the condylar cartilage.