Clinical pathologic correlation case 5: “Tooth Sleuth”

Abstract

Clinical Presentation

A 6-year-old female presented to the Cohen Children's Medical Center for routine dental examination. Her medical history was significant for attention deficit disorder (ADHD), speech delay and sensory processing disorder. She was not taking any medications and did not have any allergies. She was asymptomatic at the time of the visit. A panoramic bite-wing radiograph was taken and attention was directed to a well circumscribed intracoronal radiolucency associated with unerupted right maxillary first permanent molar (tooth #3) (Figure 1). At a follow up visit 4 months later, the lesion exhibited significant radiographic progression of the resorptive process of coronal dentin, without periapical pathology or clinical symptoms (Figure 2). A clinical examination was performed and the partially erupted tooth exhibited focal enamel dehiscence with soft tissue accumulation at the mesial aspect of the crown. The remainder of the oral mucosa and dentition was otherwise within normal limits.

Differential Diagnosis

The differential diagnoses for radiolucent defect within the dentin of the crown of an unerupted tooth include pre-eruptive intracoronal resorption (PEIR), molar-incisor hypomineralization (MIH), regional odontodysplasia (ROD), dental caries, and Turner's tooth.

The most plausible diagnosis in this case is pre-eruptive intracoronal resorption (PEIR). PEIR is characterized by a well-defined radiolucent defect located just beneath the dentin-enamel junction of unerupted teeth.^1,2 The etiology of PEIR remains unclear, but it is generally identified as an incidental finding on radiographs and is often asymptomatic.^3,4 Progressive resorption can be identified over time, necessitating timely treatment. There is no known predisposing risk factor for PEIR.³ In this case, the defect was identified through routine radiographic examination in an asymptomatic patient, consistent with the typical presentation of PEIR.

Molar-incisor hypomineralization (MIH) is another potential diagnosis. MIH is a developmental defect that affects the mineralization of enamel, primarily involving the first permanent molars and/or incisors.⁵ MIH is a chronologic enamel hypoplasia, and can be associated with an environmental insult at birth or within the first year of life, such as a diagnosed systemic medical condition, traumatic birth or childhood illnesses.⁶ It is typically associated with enamel breakdown and structural weakness which occurs after eruption.⁷ The severity of the enamel hypoplasia can range from focal discoloration of the crown to complete breakdown of the enamel and underlying dentin⁶. The enamel hypoplasia predisposes the tooth to caries which can accelerate the breakdown process. The severity of the enamel hypoplasia is often correlated with patient symptoms such as temperature sensitivity.⁶ However, in this case, the defect is primarily localized to the dentin under intact enamel.

Regional odontodysplasia (ROD) is also considered in this patient with focal developmental alteration of the crown morphology. ROD is a developmental disorder affecting enamel, dentin, and pulp of primary and permanent teeth in a focal area.^8,9 The maxillary anterior dentition are most commonly affected.⁶ Radiographically, the dentition exhibits irregular, ill-defined outlines of the dental hard tissues, resulting in a “ghost-like” appearance.⁶ Erupted teeth are hypoplastic, with abnormal crown morphology and an increased risk of caries, attrition and subsequent pulpal necrosis.⁶ The primary and permanent dentition are often affected, with the possibility of failure of eruption.⁶ The associated gingival tissues may be hyperplastic.⁶ This case demonstrates involvement of the dentin of a single permanent maxillary molar, with radiographically and clinically sound enamel. The pulp tissue is well defined and can be clearly delineated from the dentin floor. The clinical and radiographic presentation does not support ROD in this case.

Other differential diagnoses to consider include dental caries and Turner's tooth. Dental caries typically present as radiolucent defects in erupted teeth, often accompanied by enamel breakdown and clinical symptoms such as sensitivity.¹¹ Caries affects erupted or partially erupted dentition as the tooth must be exposed to a bacterial challenge and sugar substrate. In this case, the teeth are unerupted, and the enamel remains intact, ruling out dental caries as a likely diagnosis. Turner's tooth is a developmental anomaly of a permanent tooth caused by infection or trauma to the overlying deciduous tooth.¹² In this case, the affected tooth is a permanent molar with no evidence of previous trauma, and no prior primary predecessor.

Therefore, based on the radiographic presentation and clinical findings, PEIR is the most likely diagnosis, with MIH, ROD, dental caries, and Turner's tooth being less probable alternatives.

Diagnosis and Management

A problem-focused discussion was engaged with the patient's mother. Based on the extent of the resorptive process and the patient's history of dental anxiety and low cooperativity, the tooth was extracted under intravenous sedation with the oral and maxillofacial surgery division. The tooth was submitted entirely in formalin for histopathologic examination. The tooth was decalcified and stained with hematoxylin and eosin. The histology demonstrated epithelial lined granulation tissue surfacing a hard tissue defect within the coronal aspect of the molar (Figure 3). Reactive mineralized tissue and resorbed dentin was identified at the base of the granulation tissue (Figure 4). Examination of the coronal pulp revealed vital pulp tissue with reactive osteodentin at the interface of the circumpulpal dentin and surface epithelial lined granulation tissue (Figures 4 and 5). There is no evidence of caries or bacterial invasion in the dentinal tubules.

The patient presented for follow up and was observed to have normal healing of the extraction site. The remainder of her dentition remains within normal limits.

The diagnosis is pre-eruptive intracoronal resorption (PEIR).

Discussion

Pre-eruptive intracoronal resorption (PEIR), previously reported in the literature as “pre-eruptive caries” or “occult caries,” is a developmental anomaly of unerupted permanent dentition resulting in intracoronal radiolucencies with noncarious soft tissue accumulation in the hard tissue coronal defect. The permanent first molars are most commonly affected, followed by premolars and canines.¹³ The lesion is an aggressive, persistent resorptive process, although the patient typically remains asymptomatic. Often these lesions are incidental findings on routine panoramic radiographic imaging.¹⁴ Occasionally the lesions can involve the pulpal tissues and cause devitalization, resulting in odontogenic infections. These lesions can be associated with focal pinpoint enamel dehiscence, though typical clinical pit and fissure carious lesions are not identified. Eruption of the tooth into the oral cavity with subsequent exposure to the cariogenic oral flora may cause accelerated progression of the resorptive defect.

Theory

Pre-eruptive intracoronal resorption has been reported in the literature as “pre-eruptive caries” due to the similar radiographic presentation of a cariously involved erupted tooth. Once the affected tooth erupts into the oral cavity and is exposed to a sugar substrate and bacterial challenge, the resorptive process will progress and become indistinguishable from a traditional carious lesion.¹⁵ Two theories of the pathogenesis of pre-eruptive intracoronal resorption exists; the first is centered around crown morphogenesis and disordered dentin hypomineralization. The crown often presents with a clinically intact enamel shell with an underlying defect in dentin formation¹⁶. The odontoblasts deposit dentin matrix which remains unmineralized and gradually breaks down over time, resulting in an intracoronal soft tissue defect.¹⁶ The second theory is related to external resorption at the time of coronal development, resulting in a surface defect of dentin and perifollicular tissues.¹⁶ The dominant cells involved in the resorptive process are derived from fibroblast and macrophage lineages with associated interleukin-1 cytokine signaling.¹⁶ This theory is more readily accepted due to histopathologic support and recognition that many affected teeth present with focal enamel hypoplasia at the base of the pit and fissures.¹⁶ The tooth in this case report presented with a focal area of enamel loss, exposing the underlying resorptive soft tissues, supporting the second theory of PEIR.

Histopathology

Affected dentition present with a resorptive defect filled with a low grade inflammatory granulation tissue. Osteoclast-like cells are observed in Howship's lacunae at the periphery of the defect.¹⁶ There may be reactive spicules and whorls of osteodentin suspended at the base of the soft tissue or overlying the uninvolved dentin.¹⁷ Asymptomatic, vital teeth will present with a band of unaffected, noncarious dentin overlying the vital pulp which does not exhibit marked inflammation.¹⁶ Lenzi et al reported a case of an involved tooth exhibiting soft tissue composed of adipose tissue, sparse blood vessels and focal osteodentin in the intracoronal defect.¹⁷ The pulp tissue remained vital and minimally inflamed.¹⁷ The distinct lack of inflammation involving the pulpal tissues effectively rules out chronic hyperplastic pulpitis (pulp polyp) which presents with a granulation tissue extruding from the pulp chamber.^6,16 The lack of bacterial invasion of the dentinal tubules rules out an infectious carious process.

Management

Treatment of these lesions is dependent on the extent of the resorption and the eruption status of the tooth at the time of diagnosis. Seow classification of these intracoronal processes is based on the extent of dentin resorption, and use of the classification schemata may serve to guide the clinician on treatment protocols.^18,19 Minimal resorption of dentin, or single surface involvement may require a more conservative approach, which includes monitoring for progression while unerupted. Intervention if progression occurs may include sealants and excavation of the intracoronal granulation tissue and placement of a sedative or glass ionomer restoration to promote root vitality once the tooth erupts into the oral cavity.¹⁹ More severe defects such as rapidly progressive resorptive lesions, multisurface involvement or resorption of the entire coronal dentin may require immediate intervention prior to eruption, or more invasive surgical treatments such as conventional root canal therapy or extraction.¹⁹ The timing and sequence of the intervention depends on the timing of the tooth eruption, the extent of the lesion, clinical symptoms and proximity to the pulp.^19,20 Surgical exposure of the tooth may be indicated to access the lesion, arrest the resorptive process and treat with glass ionomer, pulp cap or pulpotomy procedures to prevent symptoms or devitalization of the tooth.^19,20 Glass ionomer restorations are preferred for management of these lesions due to fluoride release and moisture tolerance.^13,19 Extraction of the tooth may be necessary if the coronal defect is severe, the patient exhibits necrosis of the tooth and/or patient behavior does not permit a more conservative treatment option. While this entity is often a radiographic and clinical diagnosis, histopathologic examination may serve to provide further support for the diagnosis of PEIR in challenging cases.

Conclusion

Pre-eruptive intracoronal resorption is an uncommon dental defect which may present as an incidental finding on routine dental imaging. The resorptive process may progress over time and accelerate with eruption into the oral cavity and subsequent exposure to cariogenic oral flora. The histology of the affected tooth and periapical tissues may be nonspecific. Careful examination of the resorptive defect in an asymptomatic patient will identify granulation tissue, osteodentin, osteoclast-like giant cells and an intact, noncarious dentin bridge overlying an uninflamed vital pulp. Clinico-pathologic correlation may be necessary to diagnose this unusual condition. An unerupted tooth with intracoronal resorption mimicking caries in a pediatric patient should raise the suspicion for pre-eruptive intracoronal resorption.