Bone Abstracts

Introduction: Bisphosphonates gain increasingly greater significance in treatment oncologic diseases with bone metastasis. However, a lot of articles have lately been published in dental and oncological journals on jaw osteonecrosis (ONJ) associated with long-term ingestion of bisphosphonates. Besides extension of clinical recommendations for zolendronate use, most commonly referred to in connection with ONJ, for treatment of Paget’s diseaseand other disturbances of bone metabolism calls for further research to determine a poisonous dosage of bisphosphonates causing ONJ.

Materials and methods: 30 Wistar female rats (age 0.5–1 year, average weight 399±0.2 g) were randomly taken for investigation.

Rats were divided in three groups: 1st group (average weight 431±0.23 g), 15 rats were subject to ovariectomy; 2nd group (average weight 389±0.3 g), 15 rats, surgery was imitated; 3rd group (average weight 379 g), controls. Rats were kept in big cages at 20 °C, in good hygienic condition and were isolated from any infection that could interfere with experiment results.

1st and 2nd groups were given an i.v. injection of Aclasta (zoledronate), 0.04 ml. In 10 months i.v. injection of Aclasta was repeated to 1st and 2nd groups. Saline was injected to controls.

Results: In 2 months after the 2nd injection four out of ten spayed rats in 1st group had foci of osteonecrosis in ramus area. Mucosa was covered with fibrinous pellicle in necrotic area. Other six rats didn’t have signs of necrosis. 2nd group and controls didn’t have any signs of ONJ.

Conclusion: Necrosis rate in spayed rats composed 25% that corresponds to epidemiological evidence. Besides in our study we determined an i.v. dosage of Aclasta – 0.4 ml – which causes spontaneous development of ONJ in female rats.