Mandible / maxilla
Other inflammatory
Dental granuloma

Author: Annie Morrison, M.D. (see Authors page)
Editor: Kelly R. Magliocca, D.D.S., M.P.H.

Revised: 4 October 2018, last major update May 2014

Copyright: (c) 2004-2018, PathologyOutlines.com, Inc.

PubMed Search: Dental granuloma [title]

Cite this page: Morrison, A. Other inflammatory: dental granuloma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/mandiblemaxilladentalgranuloma.html. Accessed November 12th, 2018.
Definition / general
  • Inflamed fibrous or granulation tissue at the periapical region (or less commonly laterally along the tooth rooth) of a necrotic or infected tooth
Terminology
  • Dental pulp:
    • Unmineralized tissue composed of connective tissue, vascular, lymphatic and nervous elements
    • Occupies the central cavity portion of each tooth
    • Is a loose connective tissue (Wikipedia: Pulp (tooth)[Accessed 5 June 2018])
    • Pulpitis: Inflammation of dental pulp tissue, may manifest as a toothache
      • May be caused by trauma or bacteria accessing dental pulp
      • Reversible pulpitis: may resolve spontaneously, with medication, by correcting / removing the cause
      • Irreversible pulpitis: possibility of restoration to a healthy, disease free pulp is not possible
      • Treatment may be limited to root canal therapy or removal of the tooth, depending on the clinical and radiographic presentation
  • Apical foramen:
    • Small opening at the apex (toward root tip) of the tooth root that allows passage of neural and vascular supply of tooth
  • Periapical region:
    • Also called periapex
    • Localization around the apical foramen or region of root tip
  • Periapical granuloma:
    • Periapical granuloma (PG) is located at the apex / periapex or less commonly along the lateral surface of a necrotic or partially necrotic or infected tooth
      • May be referred to as dental granuloma (DG) or apical periodontitis (AP)
      • The terms PG and DG are both misnomers, as is not necessarily composed of granulomatous inflammation
      • PG/DG devoid of epithelium (i.e. no cyst lining) which histologically distinguishes it from a periapical cyst
  • Granuloma:
  • Odontogenic cysts:
    • All odontogenic cysts found within the jawbones are inflammatory, developmental or less commonly (and more controversially) neoplastic
    • Source epithelium from which odontogenic cysts derive include:
      • Rests of Malassez
      • Dental lamina rests
      • Reduced enamel epithelium
      • Degenerated enamel organ
      • Rarely crevicular epithelium or even surface epithelium
    • In general, inflammatory odontogenic cysts have proliferative epithelium and developmental odontogenic cysts have a more uniform epithelium, although inflammation may lead to epithelial proliferation
    • Inflammatory odontogenic cysts appear to arise in response to inflammation
    • Clinicoradiographic variants include:
      • Apical (or periapical cyst, or radicular cyst) radicular cyst: present at root apex
      • Lateral radicular cyst: present at the opening of lateral accessory root canals
      • Residual cyst remains even after extraction of offending tooth
      • Buccal bifurcation cyst
  • Epithelial rests of Malassez:
    • Discrete clusters of residual cells derived from Hertwig's epithelial root sheath
    • Small spherules of 6 - 8 epithelial cells with high nuclear to cytoplasmic ratio
    • Little or no reverse polarity of cells
  • Reduced enamel epithelium (REE):
    • Ameloblastic and epithelial cells from the outer enamel that overly an unerrupted tooth, as the REE degenerates the underlying tooth is exposed
  • Dental lamina:
    • Band of epithelium that invades the underlying ectomesenchyme of the future dental arches at 6th week gestation
    • Is major component contributing to future tooth formation
  • Enamel organ:
    • One recognizable step / stage in the formation of teeth
    • Formed from dental lamina
  • Crevicular epithelium:
    • Epithelium lining the inner aspect of the gingival sulcus
Epidemiology
  • ~75% of apical inflammatory jaw lesions
  • 50% of apical inflammatory jaw lesions that failed to respond to root canal therapy
Sites
  • Within tooth bearing portions of the maxilla and mandible
  • Apical, periapical or rarely, lateral aspect of tooth
Pathophysiology
  • Bacteria or trauma incites an inflammatory response, possibly necrosis, or permits bacteria to invade dental pulp and cause pulpitis
  • Formation of apical inflammatory lesions represents a defensive reaction secondary to the presence of microbial infection in the root canal with spread of related toxic products into the apical zone
  • Initially, the defense reaction eliminates noxious substances that exit the apical or lateral canals. With time, however, the host reaction becomes less effective with microbial invasion or spread of toxins into the apical area of tooth bearing areas of the jaws
  • In the early stages of infection, neutrophils predominate and radiographic alterations of the tooth bearing areas of the jaws are not present; this phase of periapical inflammatory disease is termed acute apical periodontitis
  • Over time, osteoclasts resorb gnathic bone, leading to a radiographically detectable periapical radiolucency
  • Some believe that the bone destruction is an attempt to prevent the spread of the infection and provide space for the arrival of defense cells specialized against the infectious process
Etiology
  • Trauma, carious lesion or bacterial colonization of developmental anomaly or diseased dental structures affecting tooth injures dental pulp
  • Tooth pulp degenerates, inflammation ensues, and inflammatory products escape from tooth via apical foramen and access the surrounding / supporting periapical region of the jaw
Clinical features
  • Variable; may have history of painful pulpitis or may be asymptomatic
  • May have dental caries / large restoration, evidence of a traumatic tooth injury, periodontal compromise involving the affected tooth
  • Non-vital reaction to electric pulp testing (may be vital reaction if dental granuloma involves one root of a multiroot tooth)
Diagnosis
  • Cannot reliably differentiate dental granuloma from periapical cyst clinically / radiographically; need histological evaluation
  • Diagnosis confirmed with removal of lesion and submission for microscopic examination
  • Ideal to have radiographic evidence of a necrotic or carious tooth to correlate with histologic findings
Radiology description
  • Radiolucent apical / periapical lesion, usually indistinguishable from periapical cyst
  • Radiolucent lesions can range from small, barely perceptible lesions to lytic lesions > 2 cm in diameter and any lesion can be circumscribed or somewhat ill defined
  • Affected teeth typically reveal loss of the apical lamina dura
  • Root resorption is not uncommon
  • Intraosseous fibrous scars are possible, especially when both cortical plates have been lost; this can give the appearance of a radiographic persistent radiolucent lesion
  • Radiographically detectable lesions at the apical / periapex or lateral region in the setting of a root canal treated tooth may have failed to resolve for several reasons:
    • Residual cyst formation
    • Persistent pulpal infection
    • Extraradicular infection (usually localized periapical actinomycotic colonization)
    • Accumulation of endogenous debris (e.g., cholesterol crystals)
    • Periapical foreign material
    • Associated periodontal disease
    • Penetration of the adjacent maxillary sinus
    • Fibrous scar formation
  • All soft tissue removed during periapical surgical procedures should be submitted for histopathologic examination as unexpected findings are not rare, including neoplasms
Radiology images

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Carious tooth with periapical granuloma

Periapical granuloma along root of carious molar

(B) Periapical granuloma

Prognostic factors
  • Vast majority have excellent prognosis after treatment
  • True periapical granulomas do not recur after appropriate treatment and are not premalignant
  • If left untreated, may develop into a periapical cyst or become secondarily acutely infected and develop into a periapical abscess, which can extend through bone and soft tissues and, less commonly, skin
  • Intraosseous fibrous scars are possible, especially when both cortical plates have been lost; this can give the radiographic appearance of a persistent radiolucent lesion
Case reports
Treatment
  • Dependent on clinical factors (including patient age, cost of treatment, patient wishes) and radiographic parameters, but may include:
    • Dental extraction of involved tooth or
    • Root canal therapy
      • Teeth treated with root canal therapy should be re-evaluated to rule out possible lesional enlargement and to ensure appropriate healing (see radiology)
      • Strong emphasis should be placed on the importance of the recall appointments
Gross description
  • Soft tissue may be adherent to root apex of an extracted tooth
  • May be firm (if fibrotic) or soft
  • May be granular and hemorrhagic (with extensive vascular proliferation)
Microscopic (histologic) description
  • Entirely variable, based on time lesion has been present, prior treatment, presence of superimposed abscess
    • Dense fibrous or granulation tissue, often with an inflammatory infiltrate of lymphocytes variably intermixed with neutrophils, plasma cells, histiocytes, mast cells and eosinophils
    • Occasionally scattered hyaline bodies (pulse granuloma giant cell hyaline angiopathy) which appear as small circumscribed pools of eosinophilic material that exhibit a corrugated periphery of condensed collagen, often surrounded by lymphocytes and multinucleated giant cells
    • Spicules of remodeling bone or dystrophic calcifications
    • Russell bodies or pyronine bodies (clusters of lightly basophilic particles) may be associated with the plasmacytic infiltrate; both are plasma cell products but are not specific for periapical granuloma
  • Epithelial rests of Malassez may be identified within granulation tissue
  • Cholesterol clefts with multinucleated giant cells, red blood cells and areas of hemosiderin pigmentation
    • In histological sections, the cholesterol crystals are dissolved out and clefts are seen surrounded by dense aggregations of multinucleated giant cells
    • The cholesterol may be due to disintegrating red blood cells in a form that readily crystallizes and incites a foreign body giant cell reaction
Microscopic (histologic) images

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Early periapical granuloma

Intermediate periapical granuloma

Late periapical granuloma

Differential diagnosis