Objective: to histologically and histomorphometrically evaluate the effect of ALN on the mandibular condyle of healthy growing animals.
Methods: healthy male Wistar rats weighing 82±7 g and aged 30 days were divided into two groups (n=4): ALN, receiving a 0.3 mg/kg/body weight weekly i.p. dose of ALN; and Sham (Sh): receiving vehicle. After 8 weeks-treatment, the animals were anesthetized and blood samples were obtained to determine calcemia (Ca), phosphatemia (PH) and total alkaline phosphatase (TAP). Following euthanasia, the hemimandibles were resected and processed histologically to obtain histological cross-sections, which were stained with: 1) H&E and 2) PAS. The following histomorphometric parameters were measured on digitalized microphotographs of both condyles: 1) number of osteoclasts per mm (N.Oc/mm), number of blood vessels (N.Bv/mm2), and volume occupied by the vessels (BvV/MV)(%); 2) trabecular volume (TbV/TV)(%), and bone tissue (BV/TbV)(%) and cartilage tissue volumes (CV/TbV)(%). The results were statistically analyzed using Student’s t test; a value of p<0.05 was considered statistically significant.
Results: there were no significant differences in serum determinations between groups. N.Oc/mm: Sh 0.84±0.20, ALN 1.69±0.35, p<0.01; N.Bv/MV(vessels/mm2): Sh 104.81±20.9, ALN 107.9±25.5, NS; BvV/MV(%): Sh 17.8±6.3, ALN 19.0±5.0, NS; TbV/TV(%): Sh 52.9±3.4, ALN 63.6 ± 0.9, p<0.001; BV/TbV(%): Sh 77.1±5.1, ALN 55.22±7.38, p<0.01; CV/TbV(%): Sh 22.9±5.1, ALN 44.78±7.38, p<0.01. Giant osteoclasts exhibiting apoptotic morphology were observed in the ALN group.
Conclusion: the present study shows that the ALN-related osteoclast dysfunction alters endochondral ossification at the level of the mandibular condyle. This finding should be taken into account when treating growing patients who take bisphosphonates.