Pre-eruptive intracoronal resorption: a familial clinical case and review

Pre-eruptive intracoronal resorption (PEIR) of the teeth is often detected incidentally on radiographs, and primarily affects the mandibular first premolar and second and third molars.¹ It is usually detected during the mixed dentition phase when crown formation is complete. However, PEIR has also been reported to occur in the primary dentition.^2,3

Radiographically, PEIR appears very similar to dental caries as a well-defined radiolucent area within coronal dentine adjacent to the enamel-dentine junction.⁴ In earlier studies, this condition was referred to using the now discounted terms of ‘pre-eruptive caries’ and ‘intra-follicular caries’.⁵ Clinically, affected teeth often have an intact enamel structure,⁶ which may be misdiagnosed as occult caries when the teeth erupt. In advanced stages, the crown may have the characteristic ‘pink’ appearance of resorption.⁷ The majority of cases are usually asymptomatic; however, lesions can sometimes involve the pulp and cause pain, swelling and cellulitis.³

Seow classified PEIR defects into three types.⁸ In type I, the lesion involves less than one-third of the dentine thickness. In type II, the radiolucent area extends between one-third and two-thirds of the dentine thickness. As for type III, the defect expands beyond two-thirds of the dentine thickness.⁸ The prevalence of PEIR has been determined to be 2–8% by subject, and 0.6–2% by tooth, with nearly half of the lesions being Seow type III.⁹

PEIR has been associated with numerous developmental defects, including ectopic positioning, delay in dental development and supernumerary teeth.^8,9 No association was found between PEIR and gender, ethnicity, medical conditions, systemic factors or fluoride supplementation.^5,9 Additionally, there has been no known hereditary link reported within the literature. To the author's knowledge, this is the first case report of PEIR occurring in two first-degree relatives. The aetiology of PEIR is still unclear, but the most widely accepted theory is intracoronal resorption by invasion of resorptive cells into forming dentine via an interruption to crown formation, which may be caused by local factors such as ectopic positioning of the tooth.^8,9

Only histological examination can conclusively differentiate between resorption and caries.¹⁰ Histological examination of PEIR has found multinucleated giant cells, osteoclasts, and chronic inflammatory cells, which is indicative of calcified dental tissue resorption.^11,12 Development of caries is influenced by four main factors: a susceptible tooth surface; bacteria; fermentable carbohydrates; and time. As an unerupted tooth is covered by alveolar bone and mucosa, it is essentially impossible for it to be exposed to the cariogenic biofilm. In the present cases, histological examination of the dental tissues was not undertaken. However, the radiographs in both cases clearly exhibit the classical appearance.

Clinical case

A 47-year-old man presented with a 3-day history of severe constant toothache in the upper left quadrant. On examination nothing remarkable was found. An orthopantomogram (OPT) was taken, which showed an unerupted upper left third molar with a Seow type III lesion involving the pulp (Figure 1). The contralateral unerupted third molar was unaffected. Subsequently, the patient was referred to a specialist oral surgeon and the upper left third molar was extracted surgically under intravenous sedation.

Some years later, the same patient's 12-year-old son was referred to a specialist orthodontist for assessment of malocclusion. A routine OPT taken detected PEIR affecting the unerupted upper left, lower left and lower right second molars (Figure 2). Caries was also noted in the lower right second premolar, which was subsequently restored. All lesions were asymptomatic. The patient was referred to a paediatric consultant for a second opinion. By this stage, all affected second molars had erupted and displayed an intact enamel structure (Figure 2). Multiple treatment options were discussed with the patient including monitoring, restoration with potential pulp therapy, or extraction. Owing to the extensive and progressive nature of the lesions, monitoring was not recommended. After further discussion, the patient and his parents opted to have the affected teeth extracted, which had the benefit of allowing the third molars to erupt into the extraction space.

Management

The management of PEIR may be influenced by several factors including: existing malocclusion; number of teeth affected; access to the affected tooth, aesthetic position of the affected tooth; patient compliance; level of oral hygiene; and the progressive nature of the lesion. When PEIR is diagnosed, the timing for intervention should be determined based on periodic radiographs to distinguish between a progressive or static lesion.¹³ A conservative approach of monitoring with or without fissure sealing has been recommended in non-progressive type I and type II lesions that are distant from the pulp, and the prognosis in these cases is often favourable.^11,14,15

In progressive lesions, immediate treatment is often recommended to stop the progression of the resorptive process, and surgical exposure may be indicated if the tooth is not close to eruption. The use of glass ionomer cement as the restoration in the surgical phase is recommended owing to its documented benefits of being fast setting, adhesive, unaffected by moisture and a source of fluoride. Once affected teeth have erupted, the restoration can be replaced with composite resin. Multiple case reports have reported positive clinical outcomes following restoration, including halted progression of the lesion, maintenance of vitality, and lack of clinical and radiographical signs of complication.^11,16–20 Interestingly, it has been reported that during restoration, the defect was a space of ‘empty dentine’ rather than intracoronal soft tissue.¹⁶ Pulp exposures with inflammation-free tissue have been treated by direct pulp capping and pulpotomy, and have showed success in the form of continued root growth and absence of clinical symptoms.^12,21–25

In situations with symptomatic teeth, poor access or extensive coronal resorption, extraction of the tooth can be considered.^11,26–29 Early detection of PEIR and determination of prognosis is crucial for appropriate orthodontic treatment planning. This has been highlighted in a previous case, whereby a mandibular first molar had been extracted for orthodontic treatment, while failing to detect PEIR in the mandibular second molar, which subsequently required removal.¹¹ Molars are seldom the teeth of choice for extraction for orthodontic purposes because these cases are more technically demanding.³⁰ However, elective extraction of healthy premolars in cases with PEIR-affected molars may not be justifiable. The space available following extraction of first or second permanent molars can be used to relieve crowding in the buccal segments, to aid antero-posterior correction and anterior open bite closure.⁴ A major advantage of extraction of compromised first or second molars is that the space gained can greatly increase the likelihood of successful eruption of third molar teeth.^{31, 32} Successful eruption of the third molar is beneficial because it can become part of the functional dentition and prevent the development of pathological sequelae, such as pericoronitis and cyst formation, which are often associated with impacted wisdom teeth.³²

Currently, the only available literature on the management of PEIR is in the form of anecdotal case reports. Additional research is needed to ascertain the aetiology, the factors that influence the rate of progression, and the long-term prognosis following treatment.

Conclusions

Pre-eruptive intracoronal resorption is a rare condition distinct from dental caries that poses a clinical challenge because there is currently no consensus regarding management. Treatment options include monitoring with possible treatment when the tooth has fully erupted, surgical exposure and restoration, pulpal therapy as required, and extraction. Further longitudinal follow-up studies are required to provide clearer evidence-based guidance on the management of PEIR. Careful viewing of radiographs of all unerupted teeth is important to enable early detection of PEIR. Early diagnosis is particularly important in the developing dentition to facilitate inclusion of affected teeth in any future orthodontic extraction plan.