Causes and Stages of Osteonecrosis of the Jaw

What Does Osteonecrosis of the Jaw Mean?

Osteonecrosis of the jaw is a condition or jaw disease that is mainly characterized by the formation of a sequestrum (refers to a piece of dead bone that has separated or become detached from the surrounding healthy bone tissue) or debris in the affected part of the jaws. As the name of the condition itself implies, osteo means bone, and necrosis means cell death. Poor healing or non healing of the jaw occurs when the underlying cause of bone death in the jaw is still persistent and when left untreated, the cells that have initially only weakened eventually die out completely, leading to a cut off of blood supply to the affected area of the jaw (ischemia). For instance, if an extraction socket does not heal properly and has several post-operative complications in the healing process, then the area may be prone to osteonecrosis. Similarly, any area of the jaw exposed to the numerous causes will be capable of delaying healing and interfering with the local or regional blood supply to the jaw. In the oral cavity, medical research shows that the areas which are affected by ONJ will not tend to be covered by gingiva or soft tissue that protects it such as the oral mucous membranes that wear out because of lack of blood supply and nourishment, eventually exposing the underlying jaw bone to the external temperature or the oral environment.

What Is the Pathogenesis of Osteonecrosis of the Jaw?

This is typically caused by a fragment of avital bone that can become separated from the healthy or sound adjacent jaw bone. This jaw pathology results from focal bone necrosis, indicating a restricted blood supply to the affected jaw region, leading to cell death in that area. Osteonecrosis, the condition at hand, is primarily associated with cell death in the affected jaw region due to ischemia or inadequate blood supply. While oral research indicates a higher probability of osteonecrosis of the jaw (ONJ) in certain individuals undergoing systemic medications or cancer therapies, various local and general factors contribute to the onset of this condition.

What Are the Causes of Osteonecrosis of the Jaw?

In most of the affected patients, the oral surgeon detects the local and systemic factors which are the causatives of the jaw osteonecrosis. These factors are:

• Cancer and Radiation Therapies: In systemically induced osteonecrosis of the jaws, the reasons commonly would be an impact of irradiation or due to the radiation therapy or treatment as seen in cancer patients (head and neck cancers specifically). In certain malignancies like multiple myelomas, osteonecrosis of the jaw would be a common finding.

• In Immunocompromised Patients or Patients On Drug Therapies: In individuals on systemic drug therapies or in immunocompromised patients, osteonecrosis of the jaw would occur due to bisphosphonate therapies, corticosteroid therapies, or drugs that affect the blood clotting.

• In Substance Abusers: In individuals who are substance abusers of Methamphetamine or Cocaine, osteonecrosis would be a possible finding (because of cell damage and eventual cell death caused due to a poor blood supply in the oral cavity).

• Systemic Conditions: Patients presenting or affected with several systemic conditions listed below would reportedly be prone to or develop osteonecrosis of the jaw. These are:

  • Paget’s bone disease (a chronic disorder that disrupts the normal bone remodeling process. It leads to the overgrowth and weakening of bone tissue).

  • Fibrous dysplasias (a rare bone disorder where normal bone is replaced with fibrous tissue).

  • Malnutrition diseases or malabsorption syndromes.

  • In patients presenting with heavy metal poisoning.

  • Osteomyelitis of the jaw.

  • In coagulopathy conditions.

  • Osteopetrosis (also known as marble bone disease or Albers-Schönberg disease, is a rare genetic disorder characterized by the abnormal thickening and hardening of bones).

  • Gorham's disease (also known as Gorham-Stout syndrome or vanishing bone disease, is an extremely rare condition characterized by the progressive loss of bone mass).

  • Infectious diseases such as HIV (Human Immunodeficiency Virus) patients, herpes zoster infections, tuberculosis, and many more.

• Dental Conditions or Treatment: Necrosis of the jaws is now known to be as per dental research directly linked to trauma to the affected area of the jaw. For instance, iatrogenic-induced lesions or trauma would result in osteonecrosis too such as improper intraosseous anesthesia, prolonged rotation of any perforator or surgical drills in the bone (during oral surgical procedures), severe trauma on the jaw bone during extraction of third molars, injuries caused to the jaw by either misuse or improper use of endodontic materials, incorrect placement of rubber dam or injuries due to chemicals used in dentistry.

• Bulimia or Self-Inflicted Lesions: These individuals may traumatize their own jaw because of psychological disturbances and that injury repeatedly may lead to osteonecrosis of the jaw.

• Medical Procedures: Laryngoscopy or endotracheal tube placement during surgery is a procedure that, according to documented case reports, may also lead to the development of osteonecrosis.

What Are the Stages of Osteonecrosis of the Jaw?

Treatment of the disease depends upon the staging and this includes:

• Stage 1 of Osteonecrosis of Jaw: This is the asymptomatic stage (without any clinical symptoms) in patients, where the exposed bone, either dead or forming a fistula, arises from the jawbone. Additionally, at this stage, there are no signs of infection. Treatment by the oral surgeon during this stage should involve regular follow-up of the ONJ lesion, followed by the elimination of the bone in the case of possible sequestration observed in the jawbone.

• Stage 2 of Osteonecrosis of Jaw: In this stage, patients who present with clinical symptoms of dead or necrotic bone such as pain in the affected area of the jaw need immediate antibiotic prophylaxis or treatment. The ONJ lesions are also clearly visible during clinical examination by the dentist or oral surgeon. After the initial antibiotic therapy, one’s dentist or surgeon may further perform debridement procedures once the inflammation subsides in the jaw to eliminate all dead bone.

• Stage 3 of Osteonecrosis of Jaw: In this stage, it is not only the visible necrotic bone or bone fistula with acute inflammation and infectious signs, but there is also the initiation of pathologic jaw fractures that can take place due to the erosion and destruction of the bone borders. Surgical elimination or resection of dead bone alongside antibiotic prophylaxis and management of post-operative complications is also needed for affected patients. Facial or jaw reconstruction surgeries should be considered by the maxillofacial surgeon to restore the jaw form and functions.

Conclusion

Osteonecrosis of the jaw (ONJ) is a condition with various local or systemic factors that affect a non-healing jaw bone, where the bone cells undergo necrosis or cell death. This condition can lead not only to moderate to severe jaw pain in the affected region but also to a life-threatening sequelae of infection if left untreated by the dental or maxillofacial surgeon.