Osteonecrosis of the Jaw: Etiology and Prevention

Recent studies have increased our understanding of the etiology of osteonecrosis of the jaw (ONJ) and its prevention. The bisphosphonates are known to precipitate ONJ and because these medications are known to be toxic to osteoclasts, it was assumed that ONJ was a disease of bone. New knowledge now questions that assumption. In addition to compromising bone, the bisphosphonates have now been found to compromise the mucosa, the vasculature, and stem cells. The findings show that the tissues involved in the maintenance of health and wound healing are directly compromised by bisphosphates. It is now assumed that the bone may not be the precipitating injury but the tissue covering the bone plays a large part in the development of the disease. Damage to the mucosa by bisphosphonates leads to the inability of the mucosa to protect the bone precipitating necrosis of the bone.

Everyone who does oral surgery knows that if bone is left exposed, it becomes necrotic and the surface layer of exposed bone sloughs off in about four weeks. Osteoclasts form under the layer of exposed bone and separate the necrotic surface layer of cortical bone from the underlying healthy bone. However, this does not occur in ONJ, but is not all due to the lack of osteoclasts, but also due to a compromised mucosa that is not able to fight the infection and heal the wound.

With this deeper understanding of ONJ, we can look at how to prevent ONJ in the first place. A recent study out of Germany used minipigs to study the development of ONJ after tooth extraction. The minipigs were divided into four groups with the results as follows:

Group 1: Extraction with no bisphosphonates.
Result: No ONJ developed.

Group 2: Bisphosphonates for 12 weeks, extraction, bisphosphonates for 8 more weeks.
Result: All developed ONJ

Group 3: Bisphosphonates for 12 weeks, extraction, wound coverage with mucoperiosteal flap coverage, antibiotics and bisphosphonates for 8 weeks.
Result: 83% developed ONJ

Group 4: Bisphosphonates for 12 weeks, 6 week holiday, extraction, wound coverage with mucoperiosteal flap, antibiotics for 8 weeks but no more bisphosphonates.
Result: 40% developed ONJ

Title: A Drug Holiday Reduces the Frequency and Severity of Medication-Related Osteonecrosis of the Jaw in a Minipig Model.
November issue of the Journal of Bone and Mineral Research J Bone Miner Res. 2020 Nov;35(11):2179-2192. doi: 10.1002/jbmr.4119. Epub 2020 Aug 10.

The study confirms what we already know. When a wound (socket) is cleaned, closed, covered, and antibiotics are prescribed, the incidence of post-operative pathology is greatly reduced. At SteinerBio, our protocol is to have the patient take a drug holiday during healing (if possible), extract, place a biocompatible bone graft, and cover with a d-PTFE membrane accompanied with antibiotics for week. In our experience, this eliminates the incidences of ONJ associated with tooth extraction. In the study, the best group had wound coverage, a drug holiday, and antibiotics, but no biocompatible bone graft. It is our opinion that if Group 4 would have had a biocompatible bone graft, ONJ would have also been eliminated.

These findings bring us to a broader question: Why is tooth extraction the only surgical procedure, in all of medicine and dentistry, left abandoned to heal without wound care? We all know the documented sequalae of not caring for the extraction socket: collapse of the ridge, dry sockets, post-operative bleeding, and leaving an open portal for any infectious agent that enters the mouth.

This is how we explain it to the patient:

We are going to remove the tooth and then we are going to care to the wound. In all of medicine, you always will have any wound cleaned, closed, and dressed. We are going to treat your extraction socket the same way. I will remove the tooth, clean out the infection, and place a bone graft to maintain the shape of your jaw. There is no animal or human material in the bone graft and everything in the bone graft goes away and leaves healthy bone. I am going to cover your bone graft with a membrane that I will remove in 4 weeks. At that time, I can place your implant without incisions, opening the gums, or sutures. It only takes about 20 minutes and most often no pain medications are needed.

This presentation takes less than one minute. After hearing the presentation, the patients now insist their extraction socket is properly grafted and covered. If they were considering waiting on having their implant placed because of financial concerns, they find the money. If they were planning to postpone the implant for social or business reasons, they rearrange their schedule to have their implant placed without surgery.

For more information on early implant placement and how science-based bone regeneration can help your patients and your practice, please give us a call or send us an email.


American Society for Bone and Mineral Research (ASBMR)

Tissue Engineering and Regenerative Medicine International Society (TERMIS)