Osteoradionecrosis and medication-related osteonecrosis of the jaw: similarities and differences


The purpose of this study was to compare medication-related osteonecrosis of the jaw (MRONJ) with osteoradionecrosis (ORN). Group 1 comprised 74 MRONJ patients (93 lesions) and group 2 comprised 59 ORN patients (69 lesions). Patient characteristics, clinical presentation of the lesions, the presence of complications, and the relationship with previous dental extractions were analyzed for both groups. Significant differences were found between the groups with regard to the characteristics of the patient populations, extraction as the precipitating event, the type of initial complaint, the prevalence of pain, and the location of the lesions. In the ORN group, significantly more patients complained of pain ( P = 0.0108) compared with the MRONJ group. Furthermore, significantly more pathological fractures ( P < 0.0001) and skin fistulae ( P < 0.0001) occurred in the ORN group. The treatment was more often conservative in the MRONJ group than in the ORN group (61.3% vs. 36.2%). Despite similarities in terms of imaging, risk factors, prevention, and treatment, MRONJ and ORN are two distinct pathological entities, as highlighted by the differences in patient characteristics, the initial clinical presentation, course of the disease, and outcome.

In 2003, Marx reported the first cases of medication-related osteonecrosis of the jaw. Initially, osteonecrosis was reported only after treatment with bisphosphonates and was referred to as bisphosphonate-related osteonecrosis of the jaw (BRONJ). Since 2014, the American Association of Oral and Maxillofacial Surgeons (AAOMS) has recommended the use of medication-related osteonecrosis of the jaw (MRONJ) in the nomenclature. The change is justified to accommodate the growing number of osteonecrosis cases associated with other anti-resorptive (denosumab) and anti-angiogenic therapies in patients without any prior use of bisphosphonates.

Radiation therapy is a frequently used treatment modality for head and neck cancer. One of the most comprehensively documented complications of radiation therapy in the head and neck region is osteoradionecrosis (ORN). The first descriptions date back to 1922 and 1926.

Both ORN and MRONJ have been described extensively in the literature. By definition, a lesion cannot be named a MRONJ lesion if it has occurred in a previously irradiated jaw. In this study, ORN and MRONJ were compared.

Materials and methods


All patients registered with ORN or MRONJ at university hospitals in Leuven, Belgium between 2005 and 2014 were included in the initial study population. None of the patients in the MRONJ group were being treated for osteoporosis or osteopenia. All MRONJ patients had been treated with intravenous (IV) bisphosphonates; none had been treated with oral bisphosphonates.

Radiographic documentation of the lesions was available for all patients. Patient characteristics and treatment and follow-up data were recorded from the medical files. The first group consisted of 74 patients (93 lesions) who had developed MRONJ. The accepted criteria of the AAOMS were used to establish the diagnosis of MRONJ. The second group consisted of 59 patients (69 lesions) with ORN. All patients in both groups were treated in the department of oral and maxillofacial surgery of the university hospitals between 2005 and 2014.

The following data were collected: identification number, date of birth, sex, tobacco use as noted in the medical records, the patient’s first complaint, number of areas with osteonecrosis and localization of the lesions, size of the exposed bony area, relationship with previous dental extractions, oro-antral communications, intraoral and extraoral fistulae, and the presence of severe complications.

Statistical analysis

The groups were compared by means of the t -test for continuous variables and the χ 2 test for categorical variables. In the case of any of the counts for the categorical variables being less than 5, Fisher’s exact test was applied instead of the χ 2 test.


Most of the patients in the MRONJ group had metastatic breast carcinoma or multiple myeloma ( Table 1 ). Fifty-nine patients (79.7%) had been treated with zoledronic acid, while 14 patients (18.9%) had been treated with denosumab and one with pamidronate.

Dec 15, 2017 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Osteoradionecrosis and medication-related osteonecrosis of the jaw: similarities and differences
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