A bony sequestrum is a fragment of dead or detached bone that separates from the surrounding healthy tissue, most often occurring in the jawbone. This condition results from the death of bone tissue, known as necrosis, which is usually triggered by a disruption in the local blood supply. The body recognizes this non-living bone as a foreign object and begins a natural process to expel it, often pushing it through the overlying gum tissue. This article explains the pathology, primary causes, and clinical methods dentists use for diagnosis and treatment.
What is a Dental Bony Sequestrum?
A bony sequestrum is a piece of bone that has become necrotic, meaning it has died due to a loss of blood flow (ischemia) to that specific area of tissue. Bone requires a continuous supply of oxygen and nutrients carried by blood vessels; when this supply is cut off, the bone cells cannot survive. The body’s immune system then attempts to isolate the non-viable piece from the living bone structure.
This dead fragment separates and acts as a physical irritant, often migrating toward the surface of the gum. Clinically, a sequestrum may present as a hard, white, sharp-edged piece poking through the gum or as a painful, firm bump underneath the soft tissue. The most common locations are the mandible (lower jaw) and the maxilla (upper jaw), particularly following dental procedures.
The sequestrum is typically a smaller, isolated shard of dead cortical bone that the body is actively trying to exfoliate. This foreign body prevents the overlying gum tissue from healing completely, often leading to chronic inflammation and delayed wound closure.
Primary Causes of Bone Death in the Jaw
The detachment of a bony sequestrum is caused by localized bone necrosis, initiated by several distinct mechanisms. One common cause is a severe bacterial infection, such as osteomyelitis, which infects the bone marrow and restricts blood flow. The resulting inflammatory pressure further compresses blood vessels, leading to bone death. Trauma, such as a complicated tooth extraction or a physical injury to the jaw, can also sever the small blood vessels that supply the bone.
A significant modern cause is Medication-Related Osteonecrosis of the Jaw (MRONJ), often associated with anti-resorptive medications like bisphosphonates. These drugs treat conditions like osteoporosis by inhibiting osteoclasts, the cells that break down old bone. This suppression of bone turnover drastically reduces the jawbone’s capacity for self-repair and healing after injury or dental surgery.
When remodeling mechanisms are impaired, bone exposed to the oral environment after an extraction cannot heal and becomes necrotic. Another cause is Osteoradionecrosis (ORN), which occurs in patients who have undergone radiation therapy for head and neck cancer. High-dose radiation damages the blood vessels and bone cells, resulting in reduced blood flow, fewer living cells, and a lack of oxygen.
This radiation-induced damage leaves the jawbone fragile and unable to recover from minor trauma, leading to the formation of sequestra. Both MRONJ and ORN compromise the bone’s natural ability to maintain vitality, making it highly susceptible to becoming non-viable fragments.
How Dentists Diagnose and Treat Sequestra
Patients often first notice a sequestrum due to persistent localized pain, swelling, or the sensation of a sharp, foreign object irritating their tongue or cheek. The overlying gum tissue frequently appears red, inflamed, or ulcerated because the fragment is pressing against or piercing the mucosa. In some cases, a whitish, hard bump or exposed bone surface is visible at the site of a recent tooth extraction or chronic irritation.
Diagnosis begins with a thorough clinical examination, where the dentist visually inspects the area and gently probes the lesion. The characteristic finding is a hard, gritty texture that confirms the presence of bone rather than a soft tissue abscess. Dental imaging, typically a periapical X-ray or a Cone-Beam Computed Tomography (CBCT) scan, is then used to confirm the diagnosis, revealing the size, shape, and exact location of the detached fragment.
Treatment depends heavily on the size and mobility of the fragment. Small, mobile sequestra may be left to naturally exfoliate, or work their way out. The dentist often prescribes an antimicrobial rinse, such as chlorhexidine, to manage any secondary infection and keep the area clean. Larger or painful fragments require a minor surgical procedure called a sequestrectomy, usually performed under local anesthesia in the dental office.
During a sequestrectomy, the dentist makes a small incision to access the fragment and carefully removes the dead bone using specialized instruments. The goal of the surgery is to remove the non-healing tissue completely to allow the healthy gum and bone underneath to finally close and repair. Following the procedure, soft tissue healing typically occurs within a few days to a week. Patients are advised to use warm salt water rinses, adhere to soft foods, and manage discomfort with prescribed pain relief.