Objective: The aim of this study was to observe the effect of decreased bite force on type I collagen mRNA in periodontal ligament (PDL) and probe into the molecular mechanism of the change in type I collagen mRNA.
Methods: Animal models were established by extracting left maxillary molars of rats. In situ hybridization was applied.
Results: The results showed that under decreased bite force, the expression level of type I collagen mRNA decreased at the sixth hour (49.7 +/- 11.1) (P < 0.05), reached the nadir on the second day (23.7 +/- 8.6), began to get over on the third day (43.1 +/- 10.3), and reached a relatively high level at the second week(56.3 +/- 9.8), but it was still lower than that of the normal bite force group (91.4 +/- 16.0)(P < 0.05); the expression of type I collagen mRNA near the cementum was higher than that near the alveolar bone.
Conclusion: These results indicate that the expression level of type I collagen mRNA is closely related to bite force.