Differential Diagnosis of Periapical Radiopacities and Radiolucencies

Periapical pathoses represent changes noted at the apices of teeth within the alveolar process that are suspected on examination, visualized via imaging, and confirmed via histopathology. They can be bone forming or destructive. There are pathologic entities that show both types of changes at the apical regions. These lesions must be identified if they are odontogenic in origin because treatment modalities differ. This article discusses identification of radiopaque and radiolucent lesions noted on radiographs. The common opacities and lucencies are described. When required, advanced imaging is used to depict changes within the bone near the periapical regions of mandibular and maxillary teeth.

Key points

  • Periapical radiolucencies are most commonly odontogenic. Nonodontogenic radiolucencies tend to be not localized and span across the mandible or maxilla within the alveolus and sometimes extend inter-radicularly.

  • Periapical radiopacities can be solitary or generalized. Solitary radiopacities can be attached to either a tooth or several teeth at the lamina dura. Occasionally, solitary opacifications, such as a cementoblastoma, mask the apical portion of the tooth due to cemental proliferation.

  • Apical lesions can be mixed where both radiolucencies and opacities can be interspersed, as seen in disorders of fibro-osseous nature, specifically the periapical osseous dysplasia, focal, or florid osseous dysplasia.

  • Large expansile radiolucencies, both septate and nonseptate, are described separately as a group because their characteristics are much different from the commonly occurring periapical lucencies that are of pulpal origin.

Introduction

Radiographic examination is the most important investigation method in general dental practice for the evaluation of dental and jaw lesions. Periapical [PA] radiographs often have an advantage to view the changes over teeth and its adjacent bone in detail. PA radiographs cannot be used, however, when a lesion is larger than 3 cm. An extraoral radiographic method, panoramic radiograph, is widely used in general dental practice to visualize the larger lesions. PA radiopacities/radiolucencies are the changes observed at the apex of the tooth. Dentists must carefully interpret these changes, however, because PA radiological observations are due to not only tooth-related pathologies but also the pathologies adjacent to the tooth/bone, which may be seen at the apex of the tooth. The most common PA pathologies can be diagnosed based on the vitality responses from the teeth. Ruling out the tooth-associated pathologies is an important step in securing a diagnosis from differential diagnosis panel of PA radiolucencies. When formulating radiological differential diagnosis, features should be evaluated carefully, such as (1) location, (2) locularity, (3) relation to dentition (4) density of lesion, (5) margin, (6) type of radiological change (radiolucent/radiopaque/mixed), (7) periosteal reaction, (8) cortical integrity, and (9) clinical presentation. This article aims to discuss dental/jaw conditions associated with radiolucent and radiopaque defects of PA region of tooth (see the list in Box 1 ).

Box 1
Periapical radiopacities and radiolucencies

  • PA radiopacities

    • Developmental conditions

      • Hypercementosis

      • PA COD

      • FCOD

      • Florid COD

      • Idiopathic osteosclerosis (enostosis, dense bone island, bone scar, focal PA osteopetrosis)

      • FD

      • Exostoses (tori)

    • Inflammatory disorders

      • Condensing osteitis (PA sclerosing osteitis, sclerosing osteitis, focal sclerosing osteitis, focal sclerosing osteomyelitis)

      • Reactional osteogenesis

      • PCO

      • SCO (chronic suppurative osteomyelitis)

      • Osteomyelitis with proliferative periostitis (Garre osteomyelitis, juvenile chronic osteomyelitis, periostitis ossificans, nonsuppurative ossifying periostitis)

    • Benign tumors

      • Cementoblastoma

      • Osteoblastoma

      • Osteoma

      • Osteoid osteoma

      • Cemento-ossifying fibroma

      • Compound odontoma

      • Complex odontoma

    • Mimicking lesions as PA radio-opacities due to superimposition

    • Malignant and metastatic lesions

      • Supernumerary teeth

      • Sialolith

      • PA radiopacities

      • Developmental

      • Dentigerous cyst

      • Lateral periodontal cyst

      • Inflammatory lesions

      • Apical periodontitis

      • PA abscess

  • PA radiolucencies

    • Developmental

      • Dentigerous cyst

      • Lateral periodontal cyst

    • Inflammatory disorders

      • Apical periodontitis

      • PA abscess

    • Cystic lesions

      • PA cyst

      • Odontogenic keratocyst

      • Glandular odontogenic cyst

    • Benign tumors

      • Ameloblastoma

    • Malignant tumors

      • Ameloblastic carcinoma

Periapical radiopaque lesions

Developmental Conditions

Hypercementosis

Definition: Hypercementosis is a non-neoplastic deposition of excessive cementum along the roots of 1 or multiple teeth. Hypercementosis can be idiopathic or associated with local and/or systemic factors, such as PA inflammation, trauma, developmental disorders, vitamin A deficiency, and Paget disease of bone. A recent study has linked hypercementosis with mutations in ENPP1 and GACI.

Epidemiology: predominantly found in adults and frequency increases with age. Mandibular molars are the most frequently affected teeth, followed by mandibular and maxillary second premolars.

Clinical findings: asymptomatic and generally incidentally detected after radiographic examination.

Radiographic findings: an affected tooth shows cemental thickening, often at the apical third of the root, with a normal periodontal ligament (PDL) space and intact lamina dura. A majority of cases result in club-shaped hypercementosis due to diffuse cemental hyperplasia that may be mild, moderate, or severe ( Fig. 1 ). Presentations may be diverse, however, including focal hypercementosis with localized nodular enlargement, circular cementum hyperplasia hypercementosis with a shirt cuff shape, and presence of multiple cemental spikes.

Fig. 1
Maxillary left premolar PA radiograph showing club-shaped hypercementosis of second premolar due to cemental deposition. Note the preservation of PDL space and lamina dura in the affected area.

Management: no treatment is necessary aside from periodic radiographic evaluation and follow-up.

Periapical cemento-osseous dysplasia

Definition: This is a rare, benign fibro-osseous dysplastic process distinct from other cemento-osseous dysplasias (CODs) by its distribution restricted to the apical region of vital anterior incisors, especially in the mandible. Although the etiology of CODs is unknown, the lesions are suggested as originating from the PDL. CODs are associated with a coexistence of simple bone cysts, propensity for osteomyelitis when exposed to oral pathogens, no malignant association, and a lack of systematic manifestations.

Epidemiology: demographics plays a key role in diagnosis with PA COD affecting predominantly black women above age 40 years. Prevalence of PA COD is between 0.24% and 5.9%. A new association has recently been published between PA COD and female patients with neurofibromatosis type 1.

Clinical findings: CODs are associated with vital teeth or extraction sites and are primarily asymptomatic. The hypovascular nature of the affected area is predisposed to osteomyelitis and pathologic fracture, and, if infection is present, then symptoms can include dull pain, purulent mucosal discharge, and jaw expansion.

Radiographic findings: all CODs present with 3 stages: (1) the osteolytic phase with radiolucent lesions, followed by (2) the cementoblast phase with mixed radiodensity lesions, and, finally, (3) the osteogenic phase with radiopaque lesions surrounded by a thin radiolucent peripheral halo. Clinically, the most common stage is the second phase with mixed radiodensity lesions ( Figs. 2 and 3 ). With cone-beam computed tomography (CBCT) images, COD presents as well-defined lesions with no tooth displacement and may exhibit expansion and thinning on cortical plates.

Fig. 2
Mandibular right lateral-canine PA radiograph as well as mandibular central incisor PA radiograph showing the mixed density masses apical to all the anterior teeth. The radiopacities are surrounded by a radiolucent rim. The teeth are all vital. This is a typical presentation of PA COD.

Fig. 3
CBCT orthogonal view of mandibular anterior region ( A ) showing changes at the PA region. Note the widened PDL as well as the opacities at the apex suggestive of the cemento-osseous changes. PCD-related radiopacities remain even after the extraction of the teeth as noted in the maxillary central incisor PA ( B ).

Management: unnecessary biopsy should be avoided to avoid risk of osteomyelitis. And, surgical intervention should be avoided, such as extraction, periodontal surgery, and implant therapy. No treatment is necessary for this self-limiting condition aside from periodic radiographic evaluation and follow-up.

Focal cemento-osseous dysplasia

Definition: This is a rare, benign fibro-osseous dysplastic process distinct from other CODs by its distribution restricted to the apical region of vital posterior teeth, especially in the mandible. Although the etiology of CODs is unknown, the lesions are suggested to originate from the PDL. CODs are associated with a coexistence of simple bone cysts, propensity for osteomyelitis when exposed to oral pathogens, no malignant association, and a lack of systematic manifestations.

Epidemiology: demographics plays a key role in diagnosis with focal COD (FCOD), affecting predominantly black women with a mean age in the mid-30s. The 2 main populations at risk as defined by a systematic review in 2008 are those with East Asian and African descent.

Clinical findings: clinical findings are similar to PA COD. Focal lesions are common in 1 or more posterior teeth ( Fig. 4 ).

Fig. 4
FCOD. Mandibular left premolar PA radiograph showing a mixed density lesion in the vicinity of the first premolar, a vital tooth. A radiolucent rim is noted encompassing the radiopaque masses suggestive of a capsule. Radiographically, the lesions are consistent with FCOD.

Radiographic findings: reference radiographic findings as PA COD.

Management: management is similar to PA COD.

Florid cemento-osseous dysplasia

Definition: rare, benign fibro-osseous dysplastic process distinct from other CODs by its distribution in multiple posterior quadrants of the maxilla and mandible in tooth-bearing areas. Although the etiology of CODs is unknown, the lesions are suggested to originate from the PDL. CODs are associated with a coexistence of simple bone cysts, propensity for osteomyelitis when exposed to oral pathogens, no malignant association, and a lack of systematic manifestations.

Epidemiology: demographics plays a key role in diagnosis with florid COD affecting predominantly black women in their fourth to fifth decades of life. In a 2003 systematic literature review, 97% were female, 59% were black, 37% were Asian, and 3% were white. Reports have documented autosomal dominant familial inheritance cases, but no underlying genetic cause has been identified.

Clinical findings: clinical findings are similar to both PA COD and FCOD.

Radiographic findings: radiographic findings are similar to other COD lesions except that the lesions are seen in more than 2 quadrants ( Fig. 5 )

Fig. 5
CBCT-based panoramic reconstruction of mandible and maxilla showing radiodense masses interspersed with lytic areas that would appear on a regular panoramic image as mixed opaque-lucent areas in all quadrants. This is pathognomonic for a radiographic diagnosis of florid expansile COD.
( Courtesy of Steven R. Singer, DDS, Rutgers School of Dental Medicine, Newark, NJ.)

Management: management is similar to PA COD and FCOD.

Idiopathic osteosclerosis (enostosis, dense bone island, bone scar, and focal periapical osteopetrosis)

Definition: an increased bone production in the jaw with unknown etiology, considered a developmental variation of normal bone architecture, and without inflammatory or systemic disease.

Epidemiology: no significant demographic differences exist in relation to gender or age. Incidence has been reported from 2.3% to 9.7%. The most common location is at the first molar region of the mandible.

Clinical findings: asymptomatic, nonexpansile, associated with a vital tooth, and generally found incidentally.

Radiographic findings: well-defined radiopaque and varied in size and shape; may present as round, elliptical, or irregular and may be anywhere in size from 2 mm in diameter to the entire height of the mandible body ( Figs. 6 and 7 ). Most lesions occurred at root apices but also may present between roots or away from teeth ; 10% to 12% of cases present with external root resorption.

Fig. 6
Mandibular left premolar PA radiograph showing a dense opacity in the region of the missing second premolar. The density is similar to cortical bone and the opacity has well-defined borders that appear to merge with the surrounding bone. This is radiographically consistent with an idiopathic osteosclerosis or a dense bone island. The entire extent of the radiopacity is not captured in this PA radiograph.

Fig. 7
Panoramic radiograph of the same area noted in Fig. 6 shows the complete extent of the radiodensity which appears to extend inferiorly to the inferior cortex. This is radiographically consistent with an idiopathic osteosclerosis or dense bone island.

Management: no treatment is needed aside from periodic radiographic evaluation and follow-up.

Fibrous dysplasia

Definition: localized, non-neoplastic, benign fibro-osseous bone disorder with 3 presentations: (1) monostotic, (2) polyostotic, and (3) polyostotic with endocrinopathies. Fibrous dysplasia (FD) is associated with a defect in stem cell differentiation with a somatic mutation in GNAS1 gene. For the purpose of this section, the focus is on monostotic craniofacial FD in the initial stages limited to the apical region as a differential for PA lesions; 0.4% of FD is associated with malignant transformation, with the craniofacial region the most common site.

Epidemiology: FD constitutes 2.5% of all bone lesions and 7% of all benign bone tumors and has an incidence of 1 in 4000 to 10,000. Craniofacial FD is rare and presents in the posterior regions of the maxilla and mandible, in younger patients, and with no to slight female gender preference.

Clinical findings: a characteristic finding is unilateral involvement with uninhibited physical expansion that can lead to severe deformity and asymmetry. May be associated with bone pain and dental anomalies, such as malocclusion, crowding, or spacing.

Radiographic findings: varied presentation depending on the stage; may appear lytic, mixed, or sclerotic. Characteristic radiographic findings for FD of the jaws are poorly defined margins and presence of a ground-glass appearance ( Fig. 8 ). In addition, associated teeth may be displaced and exhibit loss of lamina dura.

Fig. 8
Panoramic radiograph of a young patient shows mixed dentition and the inferior expansion of left mandible showing thinning of the cortex. Several erupting permanent teeth appear to have been caught in the process.

Management: treatment options range from radical surgery with complex reconstruction to bone contouring with lifelong monitoring for recurrent disease.

Exostoses (tori)

Definition: benign ectopic bone formation that is considered a variation of normal, including torus palatinus (TP) on the palate, torus mandibularis (TM) on the lingual side of the mandible unilaterally or bilaterally near the canine or premolar region, and buccal and palatal exostoses most commonly on the buccal of the maxilla. The etiology is multifactorial with genetic, environmental, and systemic factors. Bruxism often is reported in association; however, Bertazzo-Silveira and colleagues conducted a 2017 systematic review showing lack of sufficient evidence.

Epidemiology: TP and TM are common, with a prevalence of 12% to 15% and present in early adulthood, whereas buccal and palatal exostoses are less common and associated with increasing age. TP is 2 times more common in women, and TM and buccal and palatal exostoses are more common in men.

Clinical findings: asymptomatic, hard, and nontender to palpation and usually diagnosed incidentally on clinical examination.

Radiographic findings: radiopaque well-defined lesion that, although not associated with the PA region of teeth ( Fig. 9 ), may radiographically mask by superimposition or mimic other existing lesions in the area in a 2-dimensional radiograph. Thus, CBCT imaging may be indicated.

Fig. 9
Mandibular right lateral-canine PA radiograph showing superimposed mandibular tori over the apical two-thirds of the canine and first premolar roots. The radiopacity is distinct with defined borders. Although not common, in this instance, the PDL and lamina dura of both the canine and premolar are noted through the opacity.

Management: no treatment is necessary; surgical removal may be performed if the lesion interferes with speech, mastication, or fabrication of a dental prosthesis, among other reasons.

Inflammatory Disorders

Condensing osteitis (periapical sclerosing osteitis, sclerosing osteitis, focal sclerosing osteitis, and focal sclerosing osteomyelitis)

Definition: defined by the American Association of Endodontists Glossary of Endodontic Terms as a localized bony reaction secondary to low-grade inflammation and usually associated with apex of affected tooth.

Epidemiology: most commonly reported radiopaque lesion of the jaws and occurs in 4% to 7% of the general population. Predilections have been reported for women and the mandibular first molar region.

Clinical findings: the lesion often is asymptomatic and nonexpansile. An odontogenic infection or inflammatory association is essential to diagnosis ; thus, clinically may find evidence of deep caries and/or large restorations.

Radiographic findings: diffuse and uniform radiopaque lesion concentrically around the apex of the involved tooth ( Fig. 10 ).

Fig. 10
Mandibular left molar PA radiograph showing condensing osteitis in relation to both first and second molar roots. Note that both the crowns show secondary caries. Root apices show widened PDL and rarefaction suggestive of PA rarefying osteitis.

Management: nonsurgical endodontic treatment is the first treatment of choice in which most cases demonstrate partial or complete regression.

Reactional osteogenesis

Definition: inflammatory periosteal reaction in the maxillary sinus secondary to root canal infection in the PA regions of the posterior maxilla. The bony dimension between roots of teeth and maxillary sinus are significantly larger for teeth with apical pathology.

Epidemiology: only 4 cases have been reported by Estrela and colleagues, in 2015, in adult women with ages in the fifth and seventh decades. More cases are required to evaluate the true demographics of the lesion.

Clinical findings: often asymptomatic and incidentally detected on radiographic examination.

Radiographic findings: radiopaque, well-defined localized lesions at the apex of involved teeth with varied size and shape from irregular to round to ovoid ( Fig. 11 ). CBCT is especially helpful in this evaluation with the ability to view the extent of involvement without the 2-dimensional superimposition of maxillary structures.

Fig. 11
Maxillary left molar PA radiograph showing the reactional osteogenesis in relation to the palatal root apex ( arrow ). The root is in close proximity to the maxillary sinus but is draped by the floor of the sinus.

Management: the first line of treatment is nonsurgical root canal treatment, and, if unresolved, followed by surgical enucleation of the PA lesion.

Primary chronic osteomyelitis

Definition: nonodontogenic, nonsuppurative, and nonbacterial chronic inflammatory condition with unknown etiology and possible genetic, autoimmune, or lack of vascularity associations.

Epidemiology: peak onset is in young patients between ages of 10 years and 20 years and older patients above age 50 years, with no determined gender preference. Affects almost exclusively the mandible.

Clinical findings: for more than 4 weeks and often lasting longer than 2 years, exhibiting chronic intermittent episodes of pain, swelling in lower jaw, trismus, paresthesia over lower lip and/or affected area, and enlarged regional lymph nodes. In addition, there is an absence of history of trauma, radiation, or other predisposing factors; no pus, fistula, or sequestration; and no response to antibiotics.

Radiographic findings: medullary sclerosis is the most prominent finding; generally variable presentations of sclerosis, osteolysis, and periosteal (onion-skin) reactions.

Management: management is complex with difficult to understand etiology; proposed treatments vary with various surgical intervention and nonsurgical treatments, including anti-inflammatory drug therapy, antibiotics, hyperbaric oxygen, bisphosphonate treatment, and muscle relaxants.

Secondary chronic osteomyelitis (chronic suppurative osteomyelitis)

Definition: more common than primary chronic osteomyelitis (PCO), secondary chronic osteomyelitis (SCO) is a suppurative chronic inflammatory condition with well-defined etiology of bacterial invasion from dental infection, trauma, and/or surgery to the affected area. Note that SCO is the longer duration version of acute osteomyelitis.

Epidemiology: commonly affects the mandible and has no significant preference in age or gender.

Clinical findings: for more than 4 weeks exhibiting chronic episodes of pus, abscess, fistula formation, and/or sequestration. Unlike PCO, symptoms usually are resolved earlier than 2 years. Pain and swelling were the most common complaints, followed by paresthesia and tooth mobility.

Radiographic findings: varying presentations of lucent and sclerotic changes with osteolysis, bone sclerosis, sequestration, and/or periosteal reaction.

Management: treatment of the etiology is important in SCO and usually leads to resolving the condition; treatment includes surgical débridement and antibiotics.

Osteomyelitis with proliferative periostitis (garre osteomyelitis, juvenile chronic osteomyelitis, periostitis ossificans, and nonsuppurative ossifying periostitis)

Definition: special type of chronic nonsuppurative sclerosing osteomyelitis that is juvenile in nature, may be considered an early-onset form of PCO, and shows distinct thickening of the periosteum. The etiology often is associated with an odontogenic infection leading to pulpal necrosis.

Epidemiology: condition is seen almost exclusively in children and young adults with a mean age of 13 years, no gender preference, and more often affecting the mandible than maxilla.

Clinical findings: common symptoms include facial asymmetry and swelling that is usually unilateral; other symptoms possible are pain, trismus, and malaise.

Radiographic findings: CBCT aids in the understanding of the extent and etiology of the condition. Planar radiographs also show the onion-skin lamellated appearance due to periosteal new bone formation ( Fig. 12 ), coarse trabecular bone with wide marrow spaces, and modified mature trabecular bone.

Jan 7, 2020 | Posted by in General Dentistry | Comments Off on Differential Diagnosis of Periapical Radiopacities and Radiolucencies

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