29 April 2020

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Implant surgery and implant presence are both trigger for MJORN?

Giulia Palandrani

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Bisphosphonates BPS are powerful inhibitors of osteoclastic activity suppressing bone turnover. They have also antiangio-genic properties and have direct tumoricidal effects. Bisphosphonates-related osteonecrosis ( BRONJ) of the jaws was defined in 2007 as an area of exposed bone in the maxillofacial region that does not heal within 8 weeks after identification, in a patient who received BPT and had not received radiation therapy to the craniofacial region.
However, other antiresorptive and antiangiogenic therapies could cause osteonecrosis, for this reason the American Association of Oral and Maxillofacial Surgeons (AAOMS) changes the term in medication-related osteonecrosis of the jaw MRONJ.  
Dentoalveolar surgery including tooth extractions and dental implants placement is considered the major risk factor for developing MRONJ. Jacobsen and Kwon hypothesize that not only surgical implant placement but also existence of implant itself, can be associated with osteonecrosis.  

Material and Methods
In this study, 15 patients with BRONJ around dental implants were divided into 2 groups :
- Group 1 (G1) defined as ‘‘implant surgery-triggered’’ included 6 patients who developed necrosis immediately after implant surgery (from 2 to 10 months);
- Group 2 (G2) defined as ‘‘implant presence-triggered’’ included 9 patients who developed necrosis distant (from 1 to 15 years) from implant placement.  

Results  
In Group 1 five patients (83.4%) were treated with oral BPs (alendronic  acid and ibandronic acid )  for osteoporosis and one patient (16.6%) with intravenous BPS ( zoledronic acid ) for breast cancer. Mean duration of BPT was 83.7 months . Dental implants involved in the MRONJ lesions were 12, with mean number for patient of 2.
One patient (16.67%) had an osteonecrosis site without dental implant and 3 patients (50%) had dental implants (n = 5) without osteonecrosis.  
In Group 2  eight patients (88.89%) received intravenous BPS (zoledronic acid  and pamidronic acid) for malignant disease (4 breast cancer, 3 multiple myeloma, and 1 kidney cancer) and 1 patient (11.11%) was treated with oral BPS (alendronic  acid) for osteoporosis. Mean duration of BPT  was 27.8 months. dental implants involved in the MRONJ lesions were 22 with a mean number for patient of 2.4.
Two patients (22.22%) had an osteonecrosis site without dental implant and 4 patients (44.44%) had dental implants without osteonecrosis (n = 13).  

Conclusions  
Guidelines concerning implant placement in patients under BPT are ambiguous. Different studies showed that not only implant surgeryMRONJ. In fact there are evidences that bone tissue around loaded osteo-integrated dental implant is subjected to continuous remodeling, this can be consider like a local risk factor for developing MRONJ. It is necessary to explain the potential risk of ONJ not only to patients under BPT who will undergo implant surgery but also to patients who have already osteointegrated implants and have to start BPT.  
 The risk for MRONJ is lower for patients receiving oral BPS than intravenous BPS. In particular, it seems to be higher if the implant is located in the posterior areas of jawbones, if the duration of BPT is more than 3 years, and if the patient is under corticosteroid therapy.

For additional information: Medication-Related Osteonecrosis of the Jaw Around Dental Implants: Implant Surgery-Triggered or Implant Presence-Triggered Osteonecrosis?