Introduction
Nitrogen-containing bisphosphonates (N-BP) are prescribed for the treatment of bone diseases such as osteoporosis, multiple myeloma, cancer metastases, and Paget’s disease. However, bisphosphonate-related osteonecrosis of the jaws (BRONJ) has been reported as a rare complication. BRONJ occurs at a much higher rate in patients receiving intravenous N-BPs for cancer treatment versus oral N-BPs. The incidence of BRONJ in patients treated for osteoporosis is low at 0.1 %, but the incidence of BRONJ in cancer patients treated with high doses of intravenous N-BP is higher at 3 to 10 % [
1].
Currently, conservative treatment is recommended for BRONJ, in accordance with the American Association of Oral and Maxillofacial Surgeons (AAOMS) Position Paper [
2]. Recently, however, it has been reported that daily parathyroid hormone treatment is effective for BRONJ. Weekly teriparatide (TPTD; human parathyroid hormone peptide 1–34) injections have been used to treat osteoporosis in Japan [
3], but there are no reports describing the effectiveness of weekly TPTD injections for the treatment of BRONJ. Management of BRONJ is challenging and controversial, and there is currently no established drug treatment for this condition. We report two patients with stage 3 BRONJ. One patient was successfully treated with weekly PTD injections, and the other with daily TPTD injections. Changes in the levels of serum N-telopeptide of type I collagen (s-NTX) and serum N-terminal propeptide of type I collagen (P1NP) were studied.
Discussion
BRONJ is a rare condition than can be debilitating. The most frequent presentation of BRONJ is a small amount of bare bone that is not painful or inflamed, which may heal quickly, slowly, or not at all. Most cases are not as severe as in the patients presented above. Recently, it has been suggested that N-BP treatment may cause BRONJ [
4]. BRONJ is much more frequent in patients receiving intravenous N-BP for the treatment and prevention of cancer-related skeletal conditions than in patients receiving oral N-BP for the treatment of non-malignant disease [
5]. BRONJ may be associated with the type and total dose of N-BP treatment, and with a history of trauma, dental surgery, and dental infection [
6]. We described an 87-year-old female with stage 3 BRONJ that persisted after control of the bone and soft tissue infections, who required tooth extractions 3 months after the withdrawal of N-BP treatment.
The main effects of N-BP are at the lumbar spine and proximal femur, where they stop bone loss, reduce fracture risk, and increase bone mineral density. Local trauma and infection in the jaw increase the demand for bone repair, which may exceed the low turnover rate of the bone, resulting in the accumulation of necrotic bone that is recognized as osteonecrosis of the jaw.
There are some previous reports of TPTD treatment in patients with osteonecrosis of the jaws associated with N-BP therapy [
7‐
9]. Additionally, several patients treated with daily TPTD injections have now been reported, but the number of reports is limited and the evidence to date is mostly anecdotal [
10‐
12]. TPTD injection is a unique pharmacological treatment for patients with primary osteoporosis. TPTD treatment stimulates bone formation and increase bone mineral density [
13]. TPTD may counteract the mechanisms causing BRONJ by stimulating bone formation. An increase in the number of remodeling units and increased bone formation within each unit may promote healing and the removal of damaged bone. In case
2, the mandibular fracture and bone necrosis were successfully treated with daily TPTD injections, without the need for surgery, which is similar to the patient reported by Cheung and Seeman [
8], who received the administration of TPTD for osteonecrosis of the jaw in association with alendronate therapy. In both our patients, TPTD treatment was effective and achieved soft tissue coverage of exposed bone. This is the first report describing successful treatment of BRONJ with weekly TPTD injections.
In conclusion, the outcomes of the cases presented suggest that weekly TPTD injections can be effective for the treatment of stage 3 BRONJ. If weekly and daily TPTD injections are both effective, we can choose the TPTD treatment regimen according to the condition of the patient. In our patients, stage 3 BRONJ was successfully treated by either weekly or daily TPTD injections, thereby improving their quality of life. This indicates that weekly TPTD injections might result in resolution of stage 3 BRONJ by increasing the rate of bone remodeling. Our data indicate that when it is determined that a stage 3 BRONJ patient’s condition does not improve under conservative therapy and there are no other medical contraindications, daily, or weekly TPTD treatment should be considered. Our data also suggest that it may now be appropriate to initiate limited investigation of the response to weekly PTH treatment, of uncomplicated stage 2 BRONJ cases with persistent bare bone.
Open Access This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.