Anatomic factors related to bisphosphonate osteonecrosis of the jaws: a Portuguese retrospective study

The objectives of this study of bisphosphonate-related osteonecrosis of the jaws (BRONJ) were to determine local distribution, possible anatomically associated or determinant factors and other bone involvement of the disease, contributing with this new data towards the establishment of its prevalence in Portugal.

The authors made a retrospective study of patients presenting BRONJ, at the Department of Stomatology of Santa Maria University Hospital, in Lisbon (42 cases) from 1st January 2004, to April 30rd, 2011. SPSS Statistics was implemented.

There was a higher prevalence of lesions in the lower jaw (66.7%), compared to the upper jaw (26.19%) and a significantly higher occurrence in alveolar bone (95.24%). The molars and premolars were the most affected areas (highest value at 6th sextant = 35.29%). In all cases, the onset of injury occurred after a medication period of up to 90 days, spontaneously in 14.29% of patients.

For severity, BRONJ was a significant anatomoclinical entity in all 42 new cases in this study, and for discomfort (pain) in 81.1% of them. There was an anatomic correlation between the occurrence of the disease and its location in the jaws. There was a clinical association with trauma and type, route and length of administration of the bisphosphonate, with Zoledronate being administered intravenously in 76.19% of the cases. The jaws were the unique place where the disease occurred. Preventive measures should be implemented, avoiding trauma, and performing surgical procedures within 90 days after prescription.