Pre-eruptive intracoronal resorption: case report

Pre-eruptive intracoronal resorption (PEIR) is most commonly detected as an incidental finding on radiographs.¹ Its diagnosis is challenging, the presence of pre-eruptive radiographs of affected teeth aids its diagnosis.² PEIR prevalence is 2–8% by subject and 0.6–2% by tooth. Mandibular first premolar teeth are most likely to be affected, followed by second and third molars.³ This condition usually affects a single tooth, the authors are unaware of any case reports that have shown ten or more teeth to have been affected. PEIR most commonly affects teeth in the permanent dentition, with few reports affecting the primary dentition;⁴ however, this may be because radiographs are rarely taken of primary teeth prior to eruption.

Aetiology

Several theories of the aetiology of PEIR have been proposed; however, it remains poorly understood.⁵ Earlier literature refers to these lesions as ‘pre-eruptive caries’, as they were deemed to closely resemble carious lesions, however there is weak evidence for this association.¹ The most accepted theory for the aetiology of the PEIR is intracoronal resorption by invasion of resorptive cells into the forming dentine via an interruption of crown formation.⁶ Histologically, multinucleated giant cells, osteoclasts and chronic inflammatory cells have been described as related factors, suggesting that the PEIR process involves resorption of calcified dental tissues.⁷

Ectopic positioning of teeth has been found to be significantly associated with PEIR, both ectopic teeth and adjacent teeth are at higher risk for PEIR.⁸ Dental impaction has been observed in 31% of teeth with PEIR compared to only 0.1% of control teeth. In addition, children with PEIR have shown a mean delay in dental development of 0.54±0.85 years compared with controls.⁹ As most case reports discuss findings of a single affected tooth, it could be suggested that local aetiological factors cause this condition. The presence of multiple defects within the same individual may suggest a systemic factor, however this would not exclude the role of local aetiological factors.¹⁰ No association has been reported between PEIR and sex, race, medical conditions, systemic factors or fluoride supplementation.¹

Diagnosis

PEIR lesions appear radiographically as a well-circumscribed, radiolucent area that usually occurs in the coronal dentine adjacent to the enamel-dentine junction of unerupted teeth.¹ Mostly the lesions are located on the central or mesial occlusal portion of the crown, close to the enamel-dentine junction and extend to various depths of dentine. Lesions rarely involve the pulp, with the clinical crown usually remaining intact.² PEIR lesions are divided into two major types of static and developing, according to their progressive nature based on lesion size.⁵ The progress of the resorption is usually slow before the tooth erupts into the oral cavity, although some lesions undergo periods of high activity. When the affected tooth erupts into the mouth, micro-organisms may ingress into the resorbed cavity resulting in a larger ‘carious-like’ lesion.¹¹

The aim of this case report is to describe the diagnosis and management of a child who had PEIR affecting 10 teeth in the permanent dentition. The authors will discuss possible treatment options in the management of PEIR, but acknowledging that research in this area is limited.

Case report

History and clinical assessment

An 11-year-old south-east Asian healthy female child was referred for a specialist opinion by the general dental practitioner (GDP). She was referred due to a finding of multiple radiolucencies in premolar and molar teeth on bitewing radiographs, despite these teeth clinically appearing caries free. The child reported an asymptomatic dentition. An orthopantogram (OPG) radiograph taken 3 years prior as part of an orthodontic assessment showed radiolucencies were present on the affected teeth while unerupted. The child was a regular dental attender, she reported having a diet low in sugar and was brushing her teeth twice daily with a manual toothbrush and a prescription sodium fluoride toothpaste (2800ppm). She reported minimal anxiety in the dental setting and there was no family history of dental anomalies. The child presented in the permanent dentition on a class II skeletal base, with an 8mm overjet, increased overbite and class II molar relationship bilaterally. On examination the dentition was caries free with fissure sealants on the affected premolar and molar teeth (Figure 1).

Radiographic investigation

An OPG radiograph was taken in order to assess the developing dentition and the extent of dentine radiolucencies. This radiograph confirmed the presence of radiolucencies into dentine affecting the UR4, UL5, LR4, LR5, LR6, LR7, LL4, LL5 and LL7 and UR4 (10 teeth). In addition, the presence of an unerupted UL7 was observed, and it was considered that the ectopic UL8 may be impeding its eruption. These findings were compared to the OPG taken 3 years prior to the referral, which showing dentine radiolucencies in UR4, LR4, LR5, LR7, LL4, LL5 and LL7 (seven teeth) (Figures 2–4). The extent of the radiolucencies had progressed minimally. Of note, the previous OPG was not of good quality, with superimposition of structures and artefact present (Figure 2), therefore making comparison challenging. Bitewing radiographs sent by the general dental practitioner also confirmed the findings.

Management

Oral hygiene and dietary advice was reinforced as per the ‘Delivering Better Oral Health Toolkit’, including continued use of sodium fluoride 2800ppm toothpaste.¹² Fissure sealants, which showed signs of failure, were replaced with flowable composite. She was referred for an orthodontic opinion for her malocclusion, close liaison between orthodontics and paediatric dentistry clinicians was proposed for the treatment planning. It was suggested to remove the teeth most severely affected by PEIR if orthodontic extractions were required. This child was placed on a 6-monthly review cycle to monitor the progression of the lesions. The patient and her family were informed of her condition and shown the lesions on her radiographs. They were warned that if the lesions increase in size invasive treatment may be required. On the review appointments the lesions showed minimal progression, and continue to be classified as static. At the child's 6-month review appointment, the UL7 had erupted into the mouth and the lesions were stable.

Discussion

This case of pre-eruptive intracoronal resorption was diagnosed as an incidental finding on dental radiographs. Early routine dental radiography, and awareness of differential diagnoses of lesions, is essential, as an early diagnosis of PEIR will allow optimum management. PEIR can be challenging to diagnose owing to its similar appearance to other radiographic lesions, and reliance on pre-eruptive radiographs. Table 1 lists possible differential diagnoses of a PEIR lesion.⁶

Occult caries was not diagnosed clinically because the occlusal surface of the tooth appeared intact; however, radiographs showed radiolucencies into dentine, similar to PEIR.¹ Should this case have been incorrectly managed as occult caries, this patient would have carried a high burden of dental treatment at a young age. The literature has hypothesized that occult caries lesions may indeed originate from pre-eruptive dentine defects. In a study of 66 patients with clinically undetected occlusal caries, 31 (47%) showed evidence of pre-eruptive dentine radiolucencies in previous radiographs, which were exposed while these teeth were still unerupted.¹³ Turner's hypoplasia describes a permanent tooth with a hypoplastic defect in its crown. Localized apical infection, or trauma to a primary tooth, is transmitted to the underlying permanent tooth. If the infection or trauma occurs while the crown of the permanent tooth is forming, the resulting enamel will be hypoplastic and/or hypomineralized.¹⁴ An enamel pearl is an ectopic globule of enamel that is firmly adhered to the tooth root. Enamel pearls are usually adherent to the external root surface of the tooth; however, occasionally, they may be detected within the dentine and thus are named an internal enamel pearl.¹⁵ Root resorption is the loss of hard dental tissue as a result of osteoclastic cell action. In order to differentiate between these conditions, clinicians should consider the size of the cavity in relation to the time the tooth has been in the mouth following eruption. In PEIR, there may be a disproportionately large cavity relative to the short time the tooth has been in the mouth.⁶ Clinicians should take a trauma history and should consider the individual caries risk of each patient to help ascertain diagnosis of these lesions.

If PEIR is suspected, serial radiographs are recommended.¹⁶ An accurate radiographic time frame cannot be set at a determined interval.⁶ In cases of uncertainty, taking a peri-apical radiograph of the suspected tooth is recommended.^1,8 A 6–12-month interval period is the maximum follow up to assess the rate of progression of the lesion.⁶ Additional attention should be given when children present with ectopic teeth, impacted teeth or teeth with delayed eruption given the association of these conditions with PEIR.^8,9

The management of teeth with PEIR remains unclear. Previous case reports of PEIR recommended varied treatment options, ranging from a minimally invasive approach to surgical exposure of the unerupted tooth, as soon as the lesion has been detected radiographically, to arrest the progression of the resorptive process.⁴ If the PEIR lesion is extensive, or is causing symptoms, such as pain, swelling or pus discharge, removal of the affected tooth may be the treatment of choice, and orthodontic alignment to upright adjacent teeth may be required.¹⁶ A 2020 systematic review was carried out on the treatment modalities of PEIR in attempt to aide clinicians in their treatment planning of these lesions. Treatment options for unerupted and erupted teeth from this systematic review are given in Tables 2 and 3, respectively. Overall, the review found that there was no protocol currently available for the treatment of PEIR.⁵ This is most likely because of the complex nature of PEIR lesions.

In the case reported, it was decided to carry out preventive treatment and monitor the patient because the lesions were classified as static. The rate of progression of the lesions can vary, even within the same individual. It has been advised that the initial abnormality should prompt annual follow-up of other unerupted teeth.⁶ We have attributed the difference between seven teeth appearing to have PEIR lesions on the OPG in 2018, to 10 teeth having PEIR lesions on the OPG in 2021 to the quality of initial radiographs sent with the referral, because the size of the lesions remained stable. If a lesion shows a marked increase in size on follow up appointments, treatment should be provided immediately to avoid the complications related to pulp, as well as tooth fracture. This was in concordance with the systematic review that confirmed that most treatment plans were based on the progressive nature of the lesion size and eruption state in order to establish the optimum approach for each patient.⁵

Conclusion

Clinicians must be aware of PEIR as a dental diagnosis, and should consider this when reporting on radiographs of unerupted teeth. Currently, no clear treatment options or guidelines exist for the management of PEIR, likely to be due to its complex nature. Progression of these lesions can vary in rate, therefore this should be monitored closely and may determine treatment options.