Changes in bone mass in rat mandibles after tooth extraction.

An experimental study concerning changes in bone mass in trabecular bone of mandibles on rats after extractions of upper molars has been carried out. The material consisted of 32 SPF Wistar rats, fed on Nafag-184 only. Experimental and control groups consisted of eight females and eight males, each group having same average weight with respect to sex at the age of 16 weeks. At this age the upper right molars were extracted on all rats in the experimental group. The rats were sacrificed after 16 weeks. Identical increase in weight within each sex group was found. Microradiograms of two buccal-lingual 100-mu-thick ground sections at a distance of 0.5 mm through the first molar in each side of the mandible were used. Quantitation of bone mass (bone area in percent) of a trabecular bone was done by electronic point counting. No significant difference in bone mass was found between left and right sides in the control group (P greater than 0.50), whereas a significant difference was found between left and right sides in the experimental group (P approximately 0.0001) with lowest mean value in right sides. Conclusively the analysis shows that local reduction in bite force causes osteoporotic changes in trabecular bone of the jaw.