Multiple Myeloma (MM) is a cancer of plasma cells, a type of white blood cell found primarily in the bone marrow. This malignancy involves the uncontrolled growth of these cells, often leading to the destruction of bone tissue throughout the skeleton. Since the jawbones are part of this skeletal system, MM and its powerful treatments pose serious risks to a patient’s oral health. Understanding these specific dental complications is important for patients and care teams to manage risk and maintain overall well-being during treatment.
Direct Oral Manifestations of Multiple Myeloma
Cancerous plasma cells can directly infiltrate the bone marrow within the maxilla and mandible, causing damage independent of drug treatment. This process interferes with bone turnover by stimulating osteoclasts (cells that break down bone) while inhibiting osteoblasts (cells that build new bone). This imbalance results in characteristic osteolytic lesions, which appear as distinct “punched-out” holes on X-rays.
These lytic lesions, sometimes called plasmacytomas, affect the jaw in approximately 30 to 35% of symptomatic patients. The lower jaw (mandible) is more frequently involved than the upper jaw, particularly the body, angle, and ramus. Direct bone involvement can lead to symptoms such as unexplained pain, swelling, and increased tooth mobility. Swelling may be painless, but it can also cause numbness or a tingling sensation in the lower lip if the tumor compresses nearby nerves.
MM can also be associated with systemic amyloidosis, where abnormal protein deposits accumulate in organs and tissues. When amyloidosis affects the oral cavity, it can manifest as macroglossia (an enlarged tongue). Waxy papules or nodules on the tongue or buccal mucosa may also signal amyloid deposition, sometimes serving as the first clinical signs leading to an MM diagnosis.
Medication-Related Jaw Complications
The most serious dental complication from MM treatment is Medication-Related Osteonecrosis of the Jaw (MRONJ), often linked to bone-strengthening drugs. MM patients frequently receive antiresorptive medications, such as intravenous bisphosphonates (e.g., zoledronic acid or pamidronate) and the RANK-ligand inhibitor denosumab. These drugs prevent skeletal-related events like fractures and spinal cord compression caused by the cancer’s bone destruction.
The mechanism of MRONJ involves potent suppression of osteoclast activity, severely inhibiting the jawbone’s ability to heal and remodel. This lack of healing is problematic because the jaw is constantly exposed to the oral environment and risk of trauma or infection. MRONJ is defined by an area of exposed, necrotic bone in the maxillofacial region that persists for more than eight weeks after exposure to antiresorptive agents. While it can occur spontaneously, the condition is significantly more likely to follow invasive dental procedures, such as tooth extractions or implant placement.
Other MM treatments, including chemotherapy and immunomodulatory drugs, can cause distinct oral side effects. Cytotoxic chemotherapy targets rapidly dividing cells, including the mucosal lining of the mouth. This can lead to oral mucositis, presenting as painful inflammation, redness, and ulcerations. High-dose chemotherapy, such as that used before a stem cell transplant, carries a high risk of inducing severe mucositis.
Chemotherapy can also cause xerostomia (severe dry mouth) by damaging the salivary glands. Reduced saliva flow compromises the mouth’s natural cleansing capacity, significantly increasing the risk for dental decay and fungal infections like candidiasis. Immunosuppression caused by the disease and treatment can also lower the platelet count, resulting in bleeding gums and heightened susceptibility to severe oral infections.
Maintaining Oral Health During Treatment
Preventative dental care is the most effective strategy for mitigating oral complications in MM patients. A comprehensive dental evaluation and treatment of any existing disease must be completed before a patient begins anti-resorptive therapy. This pre-treatment phase should prioritize removing all active or potential sources of infection, including teeth with a poor prognosis or periodontal disease. Invasive procedures like extractions require sufficient time, typically four to eight weeks, to heal completely before the first dose of bone-modifying medication is administered.
Once treatment has begun, the primary objective shifts to minimizing trauma and infection risk. Patients on anti-resorptive drugs should strictly avoid elective invasive procedures, such as extractions, dental implants, and major periodontal surgery. If a tooth requires extraction, the oncologist and dentist must coordinate closely to determine the safest approach, which may involve a temporary discontinuation of the drug, known as a drug holiday.
Meticulous daily oral hygiene is mandatory to reduce the bacterial load and prevent infections that can trigger MRONJ. This includes gentle but thorough brushing and flossing, often supplemented by antimicrobial rinses recommended by the dental team. Proactive management of xerostomia is also important, involving the use of artificial saliva substitutes, moisturizing gels, and frequent sips of water to prevent decay.
Routine, non-invasive procedures like fillings, root canal therapy, and crown placement are generally considered safe and should be encouraged to preserve the teeth. Open communication between the patient’s oncology team and their dentist is necessary to ensure care decisions account for the patient’s MM status and current treatment effects.