Osteomyelitis

Osteomyelitis of the jaws is an inflammatory condition of bone and bone marrow caused by infectious organisms, resulting in progressive bone destruction, necrosis, and sequestrum formation.[1][2] The mandible is affected far more frequently than the maxilla, attributable to its denser cortical bone, relatively limited blood supply, and end-artery vascular pattern.[3] The disease arises predominantly through contiguous spread from odontogenic infections (periapical abscesses, periodontitis, pericoronitis), with less common routes including post-traumatic, post-surgical, and hematogenous seeding.[3][4] Radiographically, the hallmark is a mixed lytic-sclerotic pattern with ill-defined margins, often accompanied by sequestra, periosteal new bone formation, and cortical disruption.[5][6] Management combines prolonged antibiotic therapy with surgical debridement; the extent of intervention depends on disease chronicity, host factors, and response to initial treatment.[4][7]

Current Classification

The Zurich classification divides jaw osteomyelitis into three categories:[4]

• Acute osteomyelitis (AO) — suppurative infection of recent onset, typically days to weeks
• Secondary chronic osteomyelitis (SCO) — chronic suppurative disease evolving from an acute episode or persistent infection
• Primary chronic osteomyelitis (PCO) — chronic nonsuppurative disease without a preceding acute phase, encompassing diffuse sclerosing osteomyelitis and chronic recurrent multifocal osteomyelitis

The Waldvogel classification (hematogenous vs. contiguous vs. vascular insufficiency) and the Cierny-Mader staging system (anatomic type I–IV combined with host physiology A–C) are widely used in orthopedic practice and occasionally applied to jaw disease.[1][8]

Synonyms and Obsolete Terms

• Garré osteomyelitis (periostitis ossificans, osteomyelitis with proliferative periostitis) — a specific chronic variant with lamellated periosteal new bone, primarily in children[9][10]
• Chronic diffuse sclerosing osteomyelitis (DSO) — a primary chronic, nonsuppurative form with extensive medullary and cortical sclerosis[11]
• Neuralgia-inducing cavitational osteonecrosis (NICO) / fatty degenerative osteonecrosis of the jaw (FDOJ) — a controversial and poorly validated entity; current evidence is insufficient to support it as a distinct diagnosis[12][13]

Osteomyelitis of the jaws is uncommon in the era of modern antimicrobials.[4] The mandible accounts for the vast majority of cases. Mean age at presentation ranges from 43 to 53 years across large series, with a broad age range (pediatric to elderly).[4][7] Sex distribution is approximately equal in mandibular series, though some suppurative cohorts report a slight female predominance.[4][7]

Odontogenic infection is the most common etiology, followed by trauma and post-surgical causes.[4] Key predisposing host factors include diabetes mellitus, cardiovascular disease, tobacco use, immunosuppression, and psychiatric comorbidities associated with poor oral hygiene.[1][7] Antiresorptive medication use is an important risk factor that may alter the clinical and radiographic presentation.[14]

The predominant microbiology reflects oral flora rather than classic skin organisms. Streptococcus milleri group and coagulase-negative Staphylococcus species are the most frequently isolated organisms in jaw osteomyelitis, often with polymicrobial cultures.[7] Actinomyces species should be considered, particularly in chronic cases, and require prolonged anaerobic culture.[15] Less virulent organisms are significantly more common in secondary chronic disease compared with acute osteomyelitis.[4]

Presentation and Symptoms

• Pain is the most common presenting symptom, reported in approximately 90% of suppurative cases[7]
• Swelling of the affected jaw region, often with overlying erythema and induration, is present in most patients[7]
• Neurosensory disturbance (paresthesia or anesthesia of the inferior alveolar nerve distribution) occurs in roughly half of mandibular cases and is a clinically important finding[7]
• Purulent drainage — intraoral or extraoral fistulae with suppuration are characteristic of chronic suppurative disease[1]
• Trismus may develop when infection involves the masticatory space
• Fever and malaise are more prominent in acute disease; chronic forms may present with low-grade or absent systemic symptoms[1]

Tempo and Complications

Acute osteomyelitis presents over days to weeks with prominent pain, swelling, fever, and regional lymphadenopathy. Without adequate treatment, it progresses to chronic disease characterized by persistent or recurrent symptoms, sequestrum formation, and fistulous tracts.[1] Pathologic fracture is an uncommon but serious complication of advanced disease.[5] In children, Garré osteomyelitis presents as a painless or mildly painful hard swelling of the mandible, typically in the molar region.[16][17]

Red Flags

Rapidly progressive swelling with systemic toxicity, elevated white blood cell count, or neurosensory changes warrants urgent evaluation and aggressive intervention.[7]

Location and Distribution

The mandibular body and posterior mandible are the most commonly affected sites, consistent with the predominance of odontogenic etiology.[4][7] Maxillary involvement is uncommon. Disease may be focal or extend diffusely along the mandibular body, occasionally crossing the midline in chronic forms.[11] The alveolar process is typically involved first, with variable extension into the basal bone.

Periphery and Shape

• Acute osteomyelitis: Radiographic changes may be absent or subtle in the first 10–14 days. Early findings include poorly defined radiolucency with a permeative, moth-eaten pattern of bone destruction and indistinct margins. Soft tissue swelling may be the only initial radiographic sign.[2][18]
• Chronic suppurative osteomyelitis: Margins remain ill-defined, with a characteristic mixture of lytic and sclerotic changes producing an irregular, ragged periphery. The transition zone is typically wide.[6][19]
• Diffuse sclerosing osteomyelitis: Extensive, poorly marginated sclerosis without a discrete lytic focus.[11]

Internal Architecture

The internal pattern varies with disease stage and subtype:

• Lytic changes — Trabecular destruction producing radiolucent areas with a moth-eaten or permeative pattern is common in suppurative forms. Loss of normal trabecular architecture with internal round radiolucent resorptive tracts may be identified on cross-sectional imaging.[5][6][19]
• Sclerosis — Reactive sclerosis is common, particularly in chronic disease. In diffuse sclerosing osteomyelitis, extensive medullary and cortical sclerosis is the dominant finding. Sclerosis surrounding lytic foci produces the characteristic mixed lytic-sclerotic pattern.[11]
• Sequestra — Fragments of devitalized bone appearing as radiopaque bodies separated from surrounding viable bone by a radiolucent zone are a hallmark of chronic osteomyelitis. Sequestra are occasionally seen in suppurative forms and are identified more readily on cross-sectional imaging than on panoramic radiographs.[5][6][14][20]
• Non-healing extraction sockets — Persistent radiolucency at extraction sites with irregular, sclerotic margins is a common finding when the disease follows tooth removal.[5]

Periosteal Reaction and Cortical Involvement

• Periosteal new bone formation occurs in a subset of cases and is more common in medication-related osteomyelitis than in medication-unrelated forms. When present, it may appear as a single-layer, lamellated ("onion-skin"), or irregular pattern.[14]
• Garré osteomyelitis is characterized by a distinctive lamellated (onion-skin) periosteal reaction along the inferior border or buccal cortex of the mandible, producing visible cortical thickening and facial asymmetry.[9][21]
• Cortical disruption — Erosion or perforation of the buccal, lingual, or inferior cortical plates is common in chronic suppurative disease. Cortical bone resorption is less frequently observed in osteomyelitis compared with osteoradionecrosis or MRONJ on cross-sectional imaging.[5][6][22]
• Involucrum — A shell of reactive new bone surrounding necrotic bone may be identified, particularly on cross-sectional imaging.[6][20]

Effects on Teeth and Adjacent Structures

• Widening of the periodontal ligament space around teeth in the affected region
• Thickening of the lamina dura — significantly more prevalent in osteomyelitis compared with osteoradionecrosis[22]
• Root resorption is uncommon
• Tooth displacement may occur with progressive disease
• Inferior alveolar canal involvement — loss of definition or disruption of the canal walls may be seen[5]
• Pathologic fracture is a rare but recognized complication of extensive disease[5][23]

Recognized Variants

• Garré osteomyelitis (proliferative periostitis): Lamellated periosteal new bone formation producing cortical thickening and expansion, typically along the inferior mandibular border in children and adolescents. The underlying bone may show only mild lytic changes or a periapical lesion at the causative tooth.[9][17][21]
• Diffuse sclerosing osteomyelitis: Extensive cortical and medullary sclerosis with subperiosteal bone formation, condylar process deformation, and absence of sequestra or pathologic fractures. Associated masticatory muscle hypertrophy and edema may be apparent.[11]
• Chronic fibrosing osteomyelitis of the jaws (CFOJ): Minimal or undetectable abnormalities on conventional radiographs but dramatic radiolucencies on cross-sectional imaging, corresponding to empty or blood-filled cavities at surgery.[24]

MRI

MRI is highly sensitive for early detection of osteomyelitis, demonstrating bone marrow edema before radiographic changes become apparent.[2][18] Characteristic findings include:

• Low signal on T1-weighted sequences and high signal on T2-weighted/STIR sequences within the affected marrow, reflecting edema and inflammation[25]
• Gadolinium enhancement of inflamed marrow and periosteum; rim enhancement may indicate abscess formation[25]
• Soft tissue inflammatory changes, including abscess and fistulous tracts, are well delineated[18]
• In diffuse sclerosing osteomyelitis, MRI demonstrates masticatory muscle edema and hypertrophy alongside marrow signal changes[11]

MRI is limited in assessing treatment response, as marrow edema may persist for months despite microbiological cure.[2]

Nuclear Medicine

• Bone scintigraphy (Tc-99m MDP) is highly sensitive for early detection of osteomyelitis, showing increased uptake at sites of active bone turnover, but has limited specificity[2][26]
• SPECT/CT combines the high sensitivity of scintigraphy with the anatomic detail of CT and is valuable for both initial diagnosis and therapy monitoring; low-grade residual uptake is common in clinically resolved disease and reflects ongoing remodeling[23][26]
• 18F-fluoride PET/CT demonstrates markedly increased uptake in affected jawbone and may provide a more objective assessment of disease extent and activity than morphologic imaging alone[27]
• 18F-FDG PET shows moderately increased uptake and is primarily useful for follow-up assessment rather than initial diagnosis[26][27]

Medical CT

CT provides excellent cortical bone detail and is particularly useful for identification of sequestra, cortical defects, and periosteal reaction.[2][14] Trabecular sclerosis with increased Hounsfield units is characteristic of affected jawbone.[27]

The mixed lytic-sclerotic pattern, ill-defined margins, and periosteal reaction of jaw osteomyelitis overlap with several conditions. Clinical history — particularly medication use, radiation exposure, and the presence of suppuration — is essential for narrowing the differential.

The highest-risk diagnostic pitfall is failure to distinguish osteomyelitis from malignancy, as both may present with permeative bone destruction, pain, and swelling. Biopsy with microbial culture is mandatory when clinical and imaging findings are equivocal.[1][6]

Diagnostic Microscopic Findings

Suppurative osteomyelitis is characterized by necrotic bone with empty osteocytic lacunae and Haversian/Volkmann canals, intense marrow inflammation with polymorphonuclear leukocytes, macrophages, and plasma cells, and marrow vessel thrombosis.[34][35] Viable osteoclasts and periosteum are typically retained, distinguishing it from bisphosphonate-induced osteonecrosis (absent osteoclasts) and osteoradionecrosis (nonviable periosteum).[34] Bacterial colonies may be identified within sequestra.[35]

Variants

• Diffuse sclerosing osteomyelitis: Dense lamellar bone with prominent resting and reversal lines, marrow fibrosis, and minimal inflammatory infiltrate[11]
• Garré osteomyelitis: Layers of reactive periosteal new bone with intervening fibrous tissue[9][16]
• Chronic fibrosing osteomyelitis: Vital lamellar bone with microshards and splaying of trabeculae, rounded trabeculae, marrow fibrosis, and pools of erythrocytes and lipid globules[24]

Radiologic-Pathologic Correlation

Histopathologic examination alone cannot reliably distinguish osteomyelitis from MRONJ or ORN, as necrotic bone, inflammation, reactive bone formation, and bacteria are present in all three conditions.[36] Correlation with clinical history, medication exposure, radiation history, and imaging is essential for definitive diagnosis.[36]

Workup

Initial evaluation includes panoramic radiography, laboratory studies (CBC, CRP, ESR), and cross-sectional imaging (CBCT or CT) to assess disease extent.[1][26] Bone biopsy with aerobic and anaerobic cultures is the gold standard for definitive diagnosis and guides antibiotic selection.[1][15] Cultures should be incubated for 10–14 days when Actinomyces is suspected.[15]

Treatment

• Acute osteomyelitis: Antibiotic therapy for approximately six weeks is sufficient for most cases. Source control (extraction of the causative tooth, incision and drainage of associated abscess) is performed concurrently.[4]
• Chronic suppurative osteomyelitis: Combined surgical debridement (sequestrectomy, saucerization, decortication) with prolonged antibiotic therapy yields the best outcomes. Surgical debridement is performed in the vast majority of cases.[4][7]
• Antibiotic selection: Culture-directed therapy is preferred. Oral penicillins are effective first-line agents; oral antibiotics have demonstrated comparable efficacy to intravenous regimens in jaw osteomyelitis. Antibiotic resistance is commonly encountered but has not been independently associated with treatment failure.[7][37]
• Resection: Reserved for refractory cases unresponsive to debridement and antibiotics; mandibular continuity reconstruction may be required.[7][19]

Prognostic Factors and Outcomes

Successful initial treatment is achieved in approximately 86% of suppurative cases, with most requiring only a single surgical procedure.[7][37] Elevated WBC count at presentation and concurrent psychiatric comorbidities are associated with treatment failure.[7] Diabetes mellitus and penicillin allergy are independently associated with worse outcomes.[37] Persistent cases typically respond to repeat debridement with continued antibiotics.[7]

Surveillance

Clinical and radiographic follow-up is essential to monitor for disease recurrence. SPECT/CT is valuable for objective therapy response assessment; disappearance of osteolysis with residual sclerosis indicates healing, while increasing uptake with new osteolysis signals exacerbation.[23]

Osseous Dysplasia and Secondary Osteomyelitis

Florid osseous dysplasia predisposes to secondary osteomyelitis due to the hypovascular nature of the dysplastic bone.[30][32] Biopsy and surgical intervention in areas of osseous dysplasia should be avoided when possible, as inoculation with oral pathogens may precipitate chronic infection.[32] Radiographic features that distinguish superinfected osseous dysplasia from uncomplicated disease include cortical plate discontinuity, widening and decreased attenuation of the radiolucent rim, and sequestrum formation.[30]

Pediatric Considerations

Garré osteomyelitis (proliferative periostitis) predominantly affects children and adolescents, typically in the mandibular molar region secondary to odontogenic infection.[16][17] Cases lacking an identifiable infectious source may fall within the spectrum of chronic recurrent multifocal osteomyelitis (CRMO), an autoinflammatory condition that may require immunosuppressive therapy rather than antibiotics alone.[16]