Pre-eruptive intra-coronal resorption (PEIR) stands as a unique dental condition where the resorption occurs within the dentinal tissues before the tooth erupts into the oral cavity.¹ This condition is also known as pre-eruptive caries or intrafollicular caries.² Since the affected teeth are not exposed to the oral cavity, they do not undergo the histopathological processes that often occur in dental caries. Therefore, the term PEIR is preferred.³

The reported prevalence of PEIR ranges from 2%–8% per subject and from 0.6%–2% per tooth, with the mandibular first premolars and the second and third molars being the most commonly affected teeth.⁴ PEIR is asymptomatic and may be only detected incidentally in radiographs because of its rarity.⁵

The main causes of PEIR remain unclear.⁶ The correlation between PEIR and race, sex, medical conditions, systemic disorders, or fluoride intake is not well established.⁷ However, some predisposing factors, such as genetic factors, trauma, infection, and developmental anomalies, may contribute to the development of such conditions.⁸

Accurate assessment of radiographic findings in unerupted teeth enables early identification and management of PEIR defects. Early diagnosis is crucial to preventing progression and further resorption. The lesions are commonly confined to dentin, although enamel involvement may be observed in more advanced stages. Bitewing, periapical, and panoramic radiographs remain useful for confirming the diagnosis and monitoring lesion progression.⁹ Therefore, this case report presents a rare case of PEIR and the management protocol employed to reduce the risk of future complications.

The PEIR etiology and pathogenesis remain not clearly understood since there is no direct communication between the teeth and cariogenic microorganisms.³ However, apoptosis or loss of continuity of the reduced enamel epithelium is the most accepted theory.^19,20 Additionally, research indicates a significant correlation between tooth ectopic position and PEIR.^21,22

Histological findings indicate that, during the pre-eruptive stage, these lesions contain soft tissue, with multinucleated giant cells, osteoclasts, and chronic inflammatory cells contributing to dentin breakdown through micro-perforations.^4,23

PEIR often occurs in the mandible, with molars being more commonly affected than other teeth.^7,21 Most cases are usually diagnosed in mixed dentition stage during routine radiographic examinations.⁶

This dental anomaly occurs infrequently, making it less likely for clinicians to encounter such cases routinely.⁸ Consequently, limited exposure and familiarity with the condition contribute to oversight or misdiagnosis. Furthermore, PEIR typically lacks specific visible clinical symptoms that alert to its presence.^3,24 Sometimes, patients may not experience pain or discomfort unless secondary complications arise due to infection or pulp involvement.^4,8

Once a tooth erupts, it becomes susceptible to microorganisms, and these defects can become indistinguishable from dental caries. It is important to emphasize the importance of early dental visits for caregivers to prevent further disease progression.⁸ It is challenging to distinguish PEIR from dental caries, as both present as radiolucent areas on radiographs. Unlike caries, PEIR lesions are noncavitated prior to eruption. Additionally, PEIR lesions may have an intact enamel surface clinically. If left untreated, these lesions can compromise the structural integrity of the tooth, increasing the risk of fracture or post-eruptive infection.⁷

Although molar incisor hypomineralization (MIH) and PEIR are both developmental dental defects that can compromise tooth structure, they show major differences in terms of etiology, presentation, and management. MIH results from systemic disturbances during enamel formation, leading to demarcated opacities, post-eruptive enamel breakdown, and hypersensitivity. In contrast, PEIR occurs in the occlusal portion of the crown of unerupted teeth and arises from localized resorption of dentin by osteoclast-like cells after crown formation is complete; it is typically noncavitated before eruption and detected incidentally on radiographs. Mineral content is reduced in both conditions, with MIH showing decreased calcium and phosphate in hypomineralized enamel, while PEIR demonstrates resorption of dentin and reduced mineralization of the overlying enamel.²⁵

Currently, there is no established protocol for managing PEIR. Evidence suggests that the treatment of PEIR primarily depends on several factors, such as the defect size when detected, the nature of disease progression, and the expected eruption timing.^7,9,21 For lesions classified as static (nonprogressive), most authors advocate a conservative approach, monitoring the defect until tooth eruption, with restoration performed after eruption. In progressive (developing) cases, immediate intervention is recommended to prevent. Treatment options include application of sealants, restoration of the defect, IPT, root canal therapy, or extraction.^4,9,26

If the defect is confined to the dentin with no pulpal involvement and symptoms of reversible pulpitis, IPT is recommended to preserve the vitality of the tooth. In cases of pulp exposure, appropriate management involves pulp capping or root canal treatment. When the lesion is extensive or symptomatic, extraction is considered the treatment of choice.^9,15,27

Notably, several studies have explained the effectiveness of various treatment options for PEIR. Manmontri et al.²⁸ described a non-progressive PEIR lesion on the left mandibular second permanent molar of a 17-year-old boy. The lesion was first detected at 8 years and 8 months of age and was monitored clinically and radiographically annually. Given the lesion’s stability over 9 years, the patient’s low caries risk, and the high level of patient and parental compliance, a resin-based sealant was applied to the affected tooth, and the lesion was managed conservatively without operative intervention. The resin sealant was selected to prevent caries development in the affected area, thereby avoiding significant structural damage. Another case report by Yamana et al.²⁹ reported a severe PEIR lesion on the unerupted mandibular left first permanent molar of a 5-year-old girl. Radiographs revealed a large radiolucent area in the coronal portion of the tooth, extending close to the pulp. After a 12-month follow-up, the tooth had erupted into the oral cavity. Surgical removal of the overlying gingival tissue showed the tooth to be intact; however, removal of the enamel revealed a hollow space approximately 2 mm deep without pulp exposure. Calcium hydroxide was applied, and the defect was restored with cement. Three months post-treatment, the patient exhibited no signs or symptoms of abnormality.

Additionally, Mistry et al.²⁴ reported a case of a 10-year-old female patient with PEIR, diagnosed during evaluation for pain and decayed teeth in the lower right posterior region. Radiographic examination revealed PEIR affecting multiple permanent teeth, along with caries and pre-shedding resorption in primary teeth. The PEIR lesions were managed surgically with caries excavation, placement of Biodentine™, and restoration using light-cured glass ionomer cement under complete isolation. Follow-up over several months, including periodic radiographs, demonstrated pain relief, normal eruption of affected teeth, and no progression of the lesions.

Furthermore, in the case reported by Omar et al.,³⁰ a PEIR lesion was diagnosed on the permanent second molar of an 11-year-old patient. Prior to eruption, the tooth was surgically exposed, and a partial pulpotomy using MTA was performed at the site of pulp exposure. Eight weeks later, the tooth was restored with Para Core® and composite resin. The treatment approach was selected based on the severity of the lesion (to prevent further structural damage).

PEIR is a rare developmental radiolucent lesion that occurs within dentin before tooth eruption. This anomaly has a nonspecific etiology and can be detected only on radiographs in early cases. In asymptomatic cases, regular monitoring is mandatory to ensure the condition is stable. If the patient presents with symptoms such as pain or discomfort, prompt intervention should be considered to prevent pulp involvement, further resorption, or tooth loss. Therefore, early diagnosis and radiographic screening are crucial during the mixed dentition stage. Restorative treatment of progressive resorptive lesions is necessary, and long-term follow-up is essential to monitor clinical and radiographic outcomes after the treatment.