A bony sequestrum in the dental context is a fragment of dead jawbone that has separated from the living bone around it, usually working its way to the surface of the gum where it can be seen or felt as a hard, sharp piece protruding through an ulcer. It develops when the blood supply to a section of jawbone is cut off, causing that segment to die and gradually detach. The causes range from common events like difficult tooth extractions and trauma to the gum lining, to more serious conditions such as medication-related bone damage and radiation therapy for head and neck cancers. Treatment depends entirely on what triggered the bone death and how much jawbone is involved, but it almost always centers on removing the dead fragment and addressing the underlying cause.
What Exactly Happens When a Sequestrum Forms
The word “sequestrum” comes from the Latin for “to set apart,” and that is a good description of the process. When a piece of bone loses its blood supply, the bone cells die. The body then recognizes this dead fragment as foreign material and begins trying to wall it off from the healthy bone nearby. Over weeks to months, a layer of pus or inflamed tissue forms between the dead piece and the living bone, gradually loosening the fragment. In the jaw, the sequestrum tends to migrate toward the surface of the gum, eventually poking through the soft tissue and creating a persistent ulcer that will not heal on its own. The presence of that dead bone keeps the wound open by preventing normal tissue from growing over the site.
This pathological definition differs from how the term is used in radiology. On imaging, a sequestrum shows up as a dense, calcified fragment sitting inside a dark area of bone destruction, clearly separated from the bone around it. A radiologist looking at a jaw scan identifies the sequestrum by that characteristic appearance, but the image alone does not tell you whether the fragment is truly dead or just isolated. Clinical context fills in that gap.1PubMed. Bony sequestrum: a radiologic review
The Major Causes of Dental Bone Sequestration
Several distinct conditions can kill a section of jawbone and produce a sequestrum. They share the same endpoint but arrive there by different routes.
Tooth Extraction and Surgical Trauma
The most straightforward cause is damage during or after a tooth extraction. A difficult extraction can injure the thin layer of tissue (the periosteum) that wraps the jawbone and delivers its blood supply. If a patch of bone is stripped of that blood flow, it dies. In one documented case, a tooth extraction led to chronic suppurative osteomyelitis, with cone beam CT revealing a sequestrum that required surgical removal, bone debridement, antibiotics, and 20 sessions of hyperbaric oxygen therapy before the bone healed.2Europe PMC / ORL. A complication following tooth extraction: chronic suppurative osteomyelitis This is not a routine complication of extractions, but it is one that dentists and oral surgeons watch for, particularly in patients with other risk factors.
Medication-Related Osteonecrosis of the Jaw
Certain medications, especially bisphosphonates and denosumab used to treat osteoporosis and bone metastases from cancer, can impair the jaw’s ability to remodel and heal. This condition, known as medication-related osteonecrosis of the jaw (MRONJ), is one of the most common settings in which sequestra develop. The drugs work by slowing bone turnover throughout the skeleton, which is exactly what you want for preventing fractures elsewhere, but the jaw is a uniquely high-turnover bone that depends on constant remodeling. When that process stalls, any insult to the jawbone, even a routine extraction, can trigger a patch of necrosis that progresses to sequestrum formation.
A retrospective study of over 200 MRONJ patients who underwent dental procedures found that the average time from the triggering procedure to detectable sequestrum formation was roughly seven months. Patients being treated for osteoporosis developed sequestra sooner, at around six months on average, compared to roughly ten months in patients with cancer.3PubMed. Timing and Associated Factors to Formation and Detection of Sequestrum in Patients With Medication-Related Osteonecrosis of the Jaw Imaging studies of MRONJ sites consistently show more bone thickening, bone destruction, and sequestrum formation compared to healthy extraction sites.4Dentomaxillofacial Radiology. Three-dimensional clinical assessment for MRONJ risk in oncologic patients following tooth extractions
Radiation Therapy to the Head and Neck
Osteoradionecrosis (ORN) is a feared complication in cancer patients who have received radiation to the head and neck region. Radiation damages the small blood vessels in bone, leaving the tissue with reduced blood flow, fewer living cells, and lower oxygen levels. This triple hit makes the irradiated jaw fragile and slow to heal.5PubMed Central. Osteoradionecrosis of the jaw: A mini review Any subsequent dental procedure, infection, or even denture-related pressure can set off a cascade of bone death. In severe ORN cases, extensive bone destruction and sequestrum formation can develop alongside fistulas connecting the mouth to the skin surface.6PubMed Central. Osteoradionecrosis of Jaw in Head and Neck Cancer Patient Treated with Free Iliac Bone and Umbilical Fat Pad Graft
Osteomyelitis Without a Medication or Radiation Trigger
Chronic osteomyelitis of the jaw, a deep bone infection, can also produce sequestra. The infection itself cuts off local blood supply and kills bone tissue. Microbiological studies of chronic jaw osteomyelitis patients have found that the presence of a sequestrum and exposed bone directly shapes the microbial community colonizing the site, which in turn makes the infection harder to resolve without removing the dead bone.7PubMed. Analysis of the factors affecting the formation of the microbiome associated with chronic osteomyelitis of the jaw
Spontaneous Sequestration From Mucosal Trauma
A less well-known cause is oral ulceration with bone sequestration (OUBS), where minor trauma to the gum lining over a bony prominence leads to a small piece of jawbone dying and working loose. This tends to happen in areas where the bone sits close to the surface and the overlying tissue is thin, like the lingual (tongue-side) ridge of the lower jaw, bony bumps called tori, and exostoses. The thin tissue in these spots is easily scraped or bitten, and the periosteal blood supply is already sparse. When an ulcer forms, bacterial colonization and inflammation further compromise the limited blood flow, leading to localized ischemia, bone death, and eventually a tiny sequestrum that keeps the ulcer from healing.8PubMed Central. Oral Ulceration with Bone Sequestration: Key Insights for Clinicians and Their Relevance in Contemporary Clinical Practice—A Narrative Systematic Review Trauma to the underlying periosteum, combined with the anatomy of the site and possibly systemic factors, drives this particular type of focal bone necrosis.9PubMed. Oral ulceration with bone sequestration
How It Presents and Gets Diagnosed
The typical presentation is a painful, non-healing ulcer in the mouth with hard bone visible or palpable at its base. In OUBS cases, a review of clinical series found the most common scenario was a painful ulcer with exposed bone that had been present for about six to twelve weeks, often along the inside surface of the lower jaw.10PubMed. Spontaneous oral ulceration with bone sequestration: its relevance in current clinical practice In MRONJ and ORN cases, the presentation can be more dramatic: larger areas of exposed white or yellowish bone, pus drainage, foul taste, loosening of nearby teeth, and sometimes numbness of the lip if the nerve running through the lower jaw is involved.
Cone beam computed tomography (CBCT) is the workhorse imaging tool for dental sequestra. It provides a three-dimensional view of the jaw and can clearly show the dense sequestrum fragment sitting within a zone of bone destruction. CBCT studies of MRONJ and ORN have identified consistent features: mixed areas of bone hardening and bone loss, the sequestrum itself, and often perforation of the outer jawbone surface. Periosteal reaction (the body’s attempt to lay down new bone around the damage) tends to be more prominent in MRONJ than in ORN.11PubMed Central. CBCT imaging and histopathological characteristics of osteoradionecrosis and medication-related osteonecrosis of the jaw CBCT also allows clinicians to measure bone density values and score the severity of necrosis and sclerosis across the affected region.12PubMed. Cone beam computed tomography for diagnosis of bisphosphonate-related osteonecrosis of the jaw: evaluation of quantitative and qualitative image parameters
Getting the diagnosis right matters because a sequestrum on imaging can look similar to other conditions. The dense fragment within a lucent lesion can mimic certain tumors or unusual infections. A careful assessment of the sequestrum’s shape, surrounding bone changes, and clinical history usually narrows the possibilities quickly.1PubMed. Bony sequestrum: a radiologic review
Treatment Approaches
Treatment runs along a spectrum, from watchful waiting in mild cases to major reconstructive surgery in severe ones. The underlying cause and the extent of bone involvement dictate where on that spectrum a given patient falls.
Conservative Management
For small sequestra, particularly those from OUBS, the body sometimes handles the problem on its own. The dead bone fragment gradually loosens and can be lifted out with minimal intervention once it has fully separated. The clinician keeps the area clean, manages pain, prescribes antibacterial rinses, and monitors for signs that the condition is worsening rather than resolving. For osteomyelitis-related cases, broad-spectrum antibiotics are used alongside any surgical debridement to eradicate the causative bacteria.13SciELO Brazil. Differential diagnosis and clinical management of periapical radiopaque/hyperdense jaw lesions
However, conservative therapy alone has clear limits in medication-related cases. In one study comparing treatment approaches for MRONJ patients with sequestra, seven out of nine patients managed conservatively or with simple curettage (scraping) failed to heal, while all nine patients who underwent formal sequestrectomy healed successfully.14PubMed Central. Usability of surgical treatment in cases of bisphosphonate-related osteonecrosis of the jaw stage 2 with sequestrum That stark difference drove the conclusion that when a sequestrum has formed in a bisphosphonate-treated patient, waiting and hoping is considerably less effective than getting the dead bone out surgically.
Sequestrectomy
Sequestrectomy, the surgical removal of the dead bone fragment along with debridement of the surrounding damaged tissue, is the definitive treatment for most clinically significant sequestra. The goal is to remove all non-vital bone, clean the wound margins back to healthy, bleeding bone, and then close the soft tissue over the defect to restore blood supply to the area. In the upper jaw, sequestrectomy can create a communication between the mouth and the sinus cavity. To address this, surgeons have used tissue flaps, including the pedicled buccal fat pad, to seal the defect and promote healing. Case series using this technique have reported uneventful healing without dehiscence, infection, or sinus communication afterward.15PubMed Central. The use of pedicled buccal fat pad combined with sequestrectomy in bisphosphonate-related osteonecrosis of the maxilla
Hyperbaric Oxygen Therapy as an Adjunct
For osteoradionecrosis cases, where the fundamental problem is oxygen-starved bone, hyperbaric oxygen therapy (HBOT) is sometimes used before and after surgery. HBOT involves breathing pure oxygen under higher-than-normal atmospheric pressure, which drives more oxygen into the damaged tissues and stimulates new blood vessel growth. Institutional experience has found it to be a useful add-on to surgery for ORN management, and in some post-radiation wounds where surgery is not feasible, it can be therapeutic on its own.16PubMed Central. Role of Hyperbaric Medicine for Osteoradionecrosis and Post Irradiation Wounds: an Institutional Experience One case report described a patient with ORN who also had osteoporosis and was on bisphosphonates: a challenging combination. The treatment team used 35 sessions of HBOT followed by conservative sequestrectomy rather than a more aggressive jaw resection, and the patient healed completely with confirmed bone regeneration on follow-up CT and no recurrence at four years.17Bulletin of the National Research Centre. Hyperbaric oxygen therapy as a conservative approach for osteoradionecrosis of the jaw in an osteoporotic patient receiving oral bisphosphonate therapy: a case report
Bone Regeneration After the Sequestrum Is Removed
Once the dead bone is out, the question becomes whether the jaw can rebuild what was lost. In small defects from OUBS, the body typically fills in the gap without help. In larger defects from MRONJ or ORN, the bone’s compromised healing capacity means regeneration does not always happen on its own. Researchers have explored using growth factor technologies to give the bone a boost. One study used a bone-growth protein (rhBMP-2) on an absorbable collagen sponge placed into the defect after sequestrectomy in MRONJ patients. The experimental group showed a statistically significant increase in bone fill over six months, with the radiographic bone density index climbing about eleven percentage points, compared to about three percentage points in the control group that received sequestrectomy alone.18J Korean Assoc Oral Maxillofac Surg. Regenerative effect of recombinant human bone morphogenetic protein-2/absorbable collagen sponge (rhBMP-2/ACS) after sequestrectomy of medication-related osteonecrosis of the jaw (MRONJ)
In the most severe cases, where large sections of the jaw are lost, reconstruction with bone grafts from elsewhere in the body becomes necessary. Free bone grafts from the hip, combined with soft tissue coverage, have been used to rebuild mandibles devastated by ORN.6PubMed Central. Osteoradionecrosis of Jaw in Head and Neck Cancer Patient Treated with Free Iliac Bone and Umbilical Fat Pad Graft The functional stakes are high: when a sequestrum and surrounding necrosis are extensive enough, patients can lose the ability to chew and may need prosthetic rehabilitation afterward to restore oral function. One reported case involved a large sequestrum spanning the entire upper jaw in a pattern resembling a surgical fracture line, requiring resection and subsequent prosthetic work to recover quality of life.19European Journal of General Dentistry. Extensive Maxillary Medication-Related Osteonecrosis of the Jaw Treated with Surgical Resection and Prosthetic Rehabilitation: Functional Recovery and Improved Quality of Life
Prevention for At-Risk Patients
If you are taking bisphosphonates or denosumab, or if you have received radiation to the head and neck, prevention centers on minimizing jaw trauma and ensuring meticulous dental care before and during treatment. A dental evaluation before starting antiresorptive medications or radiation allows any necessary extractions or other invasive procedures to be completed while the bone still has normal healing capacity.
For patients already on these medications who need extractions, preventive protocols have been developed. One approach involves removing a margin of the bony socket wall (alveolectomy) at the time of extraction, smoothing sharp bone edges that might poke through the gum, combined with antibiotic coverage and antiseptic rinses.20Journal of Oral and Maxillofacial Surgery. Preventive Protocol for Tooth Extractions in Patients Treated With Zoledronate: A Case Series Another strategy focuses on achieving complete soft tissue closure over the extraction socket, either by advancing a flap of gum tissue or by packing the socket with platelet-rich fibrin, a blood-derived material that promotes healing.21PubMed. Tooth extractions in patients under antiresorptive therapy for osteoporosis: Primary closure of the extraction socket with a mucoperiosteal flap versus application of platelet-rich fibrin for the prevention of antiresorptive agent-related osteonecrosis of the jaw The shared principle is to minimize exposed bone and give the soft tissue every advantage in sealing the wound quickly.
For people not on any of these medications, simple awareness helps. If you notice a sharp piece of bone poking through your gum after a tooth extraction, or a mouth ulcer that is not healing after a few weeks with a hard spot at its center, see your dentist. Most post-extraction bone spicules are small and work themselves out without incident, but a persistent or worsening situation deserves professional evaluation.
Eruption Sequestrum in Children
Not every dental sequestrum is a sign of disease. Children sometimes develop what is called an eruption sequestrum: a small, irregular piece of calcified tissue sitting on the biting surface of a permanent molar as it pushes through the gum. It looks alarming to a parent who spots a hard white speck in their child’s inflamed gum tissue, but it is a self-limiting condition. The fragment is thought to be a remnant of overlying bone that gets trapped during tooth eruption.22PubMed Central. Multiquadrant presentation of eruption sequestrum: a case report and literature review It typically falls off on its own or can be easily removed by a dentist with no lasting consequences. Eruption sequestra are uncommon and primarily affect the first and second permanent molars. They have no connection to the pathological sequestra seen in adults with osteonecrosis, radiation injury, or chronic infection, and they do not indicate any underlying bone disease.
Why OUBS Is Likely Underdiagnosed
Oral ulceration with bone sequestration deserves special mention because it occupies an odd blind spot in clinical practice. Unlike MRONJ and ORN, which have established diagnostic criteria and dedicated clinical pathways, OUBS lacks a universally recognized classification. It tends to show up in patients with no history of medications or radiation, often over bony prominences on the tongue side of the lower jaw. Because it is not linked to a systemic condition, it may be dismissed as a simple ulcer or confused with more serious diseases, leading to unnecessary biopsies or referrals.
The condition is considered underreported in the medical literature, and clinicians have called for more published case experiences to help build a clearer diagnostic framework.23PubMed Central. Oral Ulceration With Bone Sequestration: Diagnostic Challenge, Management Strategy The reassuring part is that OUBS is self-limiting in most cases. Once the tiny sequestrum separates and is removed, the ulcer heals. The danger lies in misdiagnosis: if OUBS is mistaken for a malignant ulcer or early MRONJ, a patient might undergo unnecessary aggressive treatment, or conversely, if early MRONJ is mistaken for benign OUBS, a patient might not receive timely intervention for a condition that can progress.
Distinguishing between the two relies heavily on the patient’s medication and radiation history, the location of the lesion, and imaging findings. OUBS lesions tend to be small, superficial, and located at anatomical sites predisposed to mucosal trauma. MRONJ lesions tend to be associated with extraction sockets, are often larger, and show more extensive changes on CBCT. The clinical takeaway for patients is straightforward: if you have a mouth ulcer that will not heal and you can feel or see bone at its base, tell your dentist about any medications you take and any radiation you have received. That history is the single most important piece of information for getting the right diagnosis.