Case report: pre-eruptive intra-coronal radiolucencies revisited.
Abstract: AIM: Pre-eruptive intra-coronal radiolucency (PEIR) describes a radiolucent lesion located in the coronal dentine, just beneath the enamel-dentine junction of unerupted teeth. The prevalence of this lesion varies depending on the type and quality of radiographic exposure and age of patients used for assessment. The aetiology of pre-eruptive intra-coronal radiolucent lesions is not fully understood, but published clinical and histological evidence suggest that these lesions are resorptive in nature. Issues around the diagnosis, treatment planning and clinical management of this lesion are explored using previously unreported cases. CASE REPORTS: Case 1: A ten-year-old girl attended for a routine check-up. An intra-coronal radiolucency in the unerupted lower right second premolar was an incidental finding on orthopantomograph (OPT). The tooth erupted and removal of enamel revealed a space filled with soft red tissue, unlike carious dentine in appearance. The tooth was restored with an indirect pulp cap, resin modified glass ionomer base and composite resin. Tissue from the lesion was removed for histopathological investigation. Root development continued to completion and the tooth remained asymptomatic and vital. Case 2: A six-year-old girl attended for her first dental visit. An intra-coronal radiolucency in a lower right first permanent molar was noted on baseline bitewing radiographs. The lesion was monitored and fissured sealed upon eruption. The lesion was monitored annually radiographically. The tooth remained symptom free for 5 years. The patient presented on an emergency basis having fractured the distolingual cusp overlying the lesion. There was no pain and the tooth was vital. The softened dentine was removed and the tooth was restored using a preformed metal crown. Case 3: A 12-year-old girl was referred for restoration of mandibular left second permanent molar. Clinically there was extensive occlusal destruction. Review of a previous OPT showed that an intra-coronal radiolucency was present in tooth 37 at least one year prior to its eruption. The large mass of coronal soft tissue was removed, the remaining enamel shell was deemed to be unrestoreable and the tooth was extracted. The patient was referred back to an orthodontist for completion of orthodontic treatment. CONCLUSION: Early detection and classification of the PEIR lesion allows an array of individualised treatments to be provided for successful outcome.

Key words: Pre-eruptive, intra-coronal, radiolucency, resorption, idiopathic
Article Type: Clinical report
Subject: Oral manifestations of general diseases (Diagnosis)
Oral manifestations of general diseases (Care and treatment)
Oral manifestations of general diseases (Case studies)
Bone resorption (Physiological aspects)
Molars (Physiological aspects)
Authors: Counihan, K.P.
O'Connell, A.C.
Pub Date: 08/01/2012
Publication: Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2012 European Academy of Paediatric Dentistry ISSN: 1818-6300
Issue: Date: August, 2012 Source Volume: 13 Source Issue: 4
Geographic: Geographic Scope: Ireland Geographic Code: 4EUIR Ireland
Accession Number: 302113633
Full Text: Introduction

Radiographs occasionally reveal unusual intra-coronal radiolucencies in the dentine of unerupted teeth. In earlier literature, these lesions were confused with caries and incorrectly recorded as occult, hidden or pre-eruptive caries. Currently the accepted term is pre-eruptive intra-coronal radiolucency/ resorption (PEIR). This term describes an abnormal, well-circumscribed, radiolucent area within the coronal dentine of unerupted teeth [Seow, 2000; Ozden and Acikgoz, 2009]. Lesions are usually located on the central or mesial occlusal portion of the crown close to the amelodentinal junction and extend to various depths of dentine but rarely involve the pulp. The clinical crown appears intact.

PEIR can be diagnosed if there is radiographic evidence that the lesion was present pre-eruptively. Table 1 summarises the current prevalence data obtained from using bitewing (BW) radiographs [Seow et al., 1999a] and orthopantomographs (OPT) [Seow et al., 1999b; Nik and Rahman, 2003; Ozden and Acikgoz, 2009]. There are lists of previously published case reports [Seow, 2000; Ozden and Acikgoz, 2009] outlining over 70 affected teeth. Table 2 includes the three cases presented here and additional reports published since 2004. It is evident that PEIR most commonly affects a single tooth but multiple teeth can be affected [Walton, 1980; Seow, 1998; Hata et al., 2007]. The most commonly affected teeth are molars and premolars, although other tooth types have been reported [Rankow et al., 1986; Hata et al., 2007]. There has been only one report of PEIR in the primary dentition [Seow and Hackley, 1996], however this case presented unconventionally as an acute infection shortly after eruption of the second primary molar and resorption was shown histopathologically in the extracted tooth.

Various aetiologies of pre-eruptive intra-coronal radiolucencies have been suggested over the years, originally proposed by Skillen [1941]. Chronic periapical inflammation of the preceding primary tooth was one of the first theories postulated [Muhler, 1957], but the majority of teeth affected do not have a primary precursor. Dental caries is not likely, as infection with cariogenic microorganisms has not been shown in unerupted teeth [Davidovich, 2005]. It has been suggested that the lesion arises when certain sections of the tooth fail to mineralise properly during development. However, Seow and Hackley demonstrated that the radiolucency became evident after crown development is complete. They inferred that the lesion could not be the result of an intrinsic disturbance of mineralisation.

It is widely accepted now that the process in PEIR is one of resorption. Markers representative of resorption such as multinucleated giant cells, osteoclasts and chronic inflammatory cells have been described in the histopathology reports in numerous case reports [Blackwood, 1958; Grundy et al., 1984; Brooks, 1988; Seow and Hackley, 1996]. The triggering factors are as yet unknown. The classification of tooth resorption in general, is not well understood and considerable challenges exist when trying to determine aetiology and predict clinical behaviour of resorptive lesions [Heithersay, 2007]. It has been suggested that abnormal local pressures, such as ectopic position of the tooth bud, may be a stimulating factor [Seow, 1999b].

It had been assumed that PEIR would progress unless intervention occurs but the various case reports showed significant variation in the clinical course for PEIR lesions. The progress of the lesion is slow before the tooth erupts into the oral cavity, although some lesions do progress rapidly [Holan et al., 1994; Seow, 1998; Klambani et al., 2005; Hata et al., 2007]. A number of cases suggest surgical exposure of the unerupted tooth to restore the lesion to avoid continued destruction of coronal structure. There are no reports of progression when the lesions have been removed and restored [Table 3]. When the affected tooth erupts, it is assumed that microorganisms may ingress through microscopic external enamel openings into the resorbed cavity to cause further breakdown, so that a large carious lesion results [McNamara et al., 1997; Seow, 2003]. The majority of case reports suggest that the affected teeth remain asymptomatic as the lesion rarely extends into the pulp.

No gender or racial predilection has been reported but Nik and Rahman [2003] reported a far greater subject prevalence in Malaysian subjects than in other populations [Table 1]. No systemic factors seem to predispose a child to PEIR [Seow, 2000]. The only significant association reported to date is the high prevalence of ectopically positioned teeth that are associated with these defects [Seow et al., 1999a; Ozden and Acikgoz 2009].

Case Reports

Case 1: An intra-coronal radiolucency in the unerupted lower right second premolar was an incidental finding on OPT of a 10 year old girl (Figure. 1a). The tooth was monitored radiographically prior to and during eruption. The lesion did not increase in size and there was continued root development (Figure 1b). The tooth erupted without incident. It was clinically sound, asymptomatic, with a slight distal rotation (Figure 1c). There had been no increase in size of the lesion over time. The tooth was anaesthetised and isolated under rubber dam. Cavity preparation in the mesio-occlusal aspect of the tooth revealed an empty space, the base of which was filled with a soft reddish material (Figure 1d). This was removed with a spoon excavator. The tooth was restored with an indirect pulp cap, resin modified glass ionomer base and composite resin, and a fissure sealant was placed in the distal pit (Figure 1e).

Root development continued to completion (Figure 1f) and the tooth remained asymptomatic and retained vitality. Histological examination was inconclusive due to small sample size and contamination of the sample with oral bacteria.

[FIGURE 1 OMITTED]

Case 2: An intra-coronal radiolucency in the partially erupted lower right first permanent molar was noted on baseline bitewing radiographs of a six-year-old girl (Figure 2a). The lesion was monitored during eruption and the occlusal surface was macroscopically intact. The tooth was fissure sealed upon eruption with RMGIC and subsequently with a resin sealant (Figure 2b). A conservative approach was taken and the lesion was monitored annually. The lesion did not increase in size and the sealant was intact (Figure 2c). At age 11 years (5 years following diagnosis) the disto-lingual cusp overlying the PEIR lesion fractured and the tooth was restored using a preformed metal crown. There was no evidence of caries. The tooth remained vital and asymptomatic.

[FIGURE 2 OMITTED]

Case 3: A 12-year-old girl was referred by her orthodontist for restoration of the mandibular left second permanent molar. The left first permanent molar had been extracted previously as part of the orthodontic treatment plan and cavitation in the occlusal surface was noted when the tooth was partially erupted. The orthodontist attempted to extrude the tooth to facilitate restoration. Clinically there was extensive occlusal destruction, with a large pulp polyp. The tooth had an unusual radiographic appearance (Figure 3a). A previous OPT revealed that an intra-coronal radiolucency was present in the second molar at least one year prior to its eruption and prior to the extraction of the first permanent molar (Figure 3b). The second molar was anaesthetised and isolated under rubber dam. Following removal of the soft tissue mass, the remaining enamel shell was deemed unrestoreable and the tooth was extracted. The tooth and associated soft tissue were sent for histopathological analysis.

Histologically there was a normal amelodentinal junction and enamel matrix. Irregular resorption was present on the pulpal surface with osteoclast like giant cells and granulation tissue compatible with PEIR (Figure 3c). The failure to detect PEIR in the second molar prior to the extraction of the first permanent molar has complicated the orthodontic treatment plan.

[FIGURE 3 OMITTED]

Discussion

Radiographs are usually taken in children for caries detection and for orthodontic treatment planning. Although the prevalence rates have been reported using bitewing radiographs and OPTs, PEIR can be detected using either radiograph. All radiographs must be examined completely for incidental findings. There is a high prevalence of ectopically positioned teeth affected by PEIR or being adjacent to teeth with PEIR [Seow et al., 1999a; Ozden and Acikgoz 2009]. Good quality radiographs that include the maximum information may result in early diagnosis of PEIR. Radiographs of these three cases were examined and PEIR affected a single tooth only with no anomalies associated with these affected teeth.

The aetiology of these lesions is as yet, not fully understood and more research is needed in this area. However, it appears that retrospective diagnosis is common and gaining adequate numbers of teeth or tissue for investigation may be difficult. Regardless of the cause of the lesion, the clinician must choose the treatment modality that is most suitable for the particular clinical presentation. Historically, the dental literature recommended immediate surgical intervention and restoration to limit the extent of the resorptive lesion and prevent its progression into the dental pulp. Tooth resorption can be continuous and potentially aggressive [Heithersay, 2007]. However, not all lesions progress and if progression is not detectable radiographically, restorative treatment can be delayed until the tooth is fully erupted. This approach was adopted in Case 1 where the lesion was removed and the tooth restored upon eruption. Similar to many other reports, there was no communication with the pulp chamber and the integrity of the pulp was maintained. In Case 2 of this series, restorative treatment was deferred for 5 years as radiographically the lesion did not progress and clinically the tooth was intact in a caries free dentition. Moskovitz and Holan [2004] previously reported a non-progressive lesion in an unerupted second permanent molar, however they restored the lesions on eruption of the tooth similar to Case 1.

Case 2 illustrates an active decision not to restore a non-progressive lesion in a tooth following eruption. The majority of case reports suggest that the affected teeth remain asymptomatic as the lesion rarely extends into the pulp. The controversy therefore is when or if the clinician should intervene? There is no consensus in the various case reports as many clinical variables can determine the outcome. There are conflicting reports on whether these lesions are progressive or non-progressive. Case 2 is the first report of long-term evaluation without intervention to restore the lesion upon eruption. Radiographically the lesion did not progress in size radiographically but the undermined cusp fractured after 5 years. It could be argued that radiographs are an insensitive way to evaluate any dimensional change in a three dimensional lesion. There are no case reports of progression or reactivation following removal of the PEIR lesion and its replacement with a restoration (Table 3). In some cases, apexogenesis or pulpectomy has been provided either electively or following exposure with a successful outcome [Ignelzi et al.,1990; O'Neal et al., 1997]. This was the intended treatment for Case 3, however the extent of coronal resorption was too great to allow restorative treatment.

The management of teeth with PEIR should be centered on early diagnosis and treatment at an appropriate time. If a relatively small lesion is detected or if a tooth is close to eruption, it may be monitored carefully until the tooth erupts into the oral cavity. Early intervention would be appropriate, using restoration of lesion for patients at high risk for caries, those with poor attendance record or those with limited co-operation. Radiographic monitoring of the lesion size will direct if intervention pre-eruptively may be necessary.

When lesions are large, appear to be encroaching on the pulp or where the lesion appears to be enlarging, it may be appropriate to surgically expose the tooth in order to allow curettage and restoration. Where there has been pulp involvement without infection, the pulp has remained vital and further root development occurred [Ignelzi et al., 1990; O'Neal et al., 1997]. As mentioned previously, recurrence of the resorption after curettage of the lesion has not been reported in the literature, so that restoration of the lesion is a valid treatment option.

The cases presented add to the treatment modalities that may be offered when PEIR is diagnosed. Fewer than 100 cases have been reported in the literature yet the reported prevalence suggests that this lesion is not uncommon. Teeth affected by or adjacent to teeth with PEIR lesions may be ectopically positioned. All clinicians must be able to differentiate between PEIR and carious lesions and discuss options appropriate to the patient on an individual level. In two of the cases the lesions were diagnosed prior to eruption (Cases 1 and 2). Both lesions were monitored until the teeth involved were fully erupted and definitive restoration was possible. Neither of the lesions increased in size nor changed in shape during the monitoring period. This allowed treatment to be postponed until an appropriate time. The rate of progression varies and must be monitored. In Case 2, this involved a period of several years--the occlusal surface of the tooth was protected with a fissure sealant. In both affected teeth root development continued to completion and both teeth have retained vitality.

Case 3 was different in that the lesion was diagnosed post-eruptively and the tooth involved had presented with a large destructive lesion, similar to that reported by Rankow and co-workers [Rankow et al., 1986]. The unusual radiographic appearance of the tooth prompted retrieval of all previous radiographs of the tooth in question. An OPT showed that an intra-coronal radiolucency had been present in the second permanent molar at least eighteen months prior to presentation, while the tooth was unerupted. Unfortunately, the lesion had not been detected at this stage and extraction of first permanent molars was planned by the orthodontist. Forced eruption of the tooth to facilitate restoration was a reasonable option however the extent of the lesion was too great. In retrospect, the first molar could have been maintained or surgical exposure and curettage of the PEIR lesion could have been offered. This case emphasises the importance of assessing all radiographs including all unerupted teeth in cases where extractions are planned as part of an orthodontic treatment plan.

Conclusion

A number of treatment options are available if PEIR is diagnosed either via bitewing radiographs or OPT. PEIR appears to be resorptive in nature yet the stimulus for this resorption is not known. The location of the lesion is predictable and it appears that the lesions can be progressive or non-progressive. The majority of lesions are not aggressive and can be controlled by curettage and restoration. The risk of pulp involvement is low. Clinicians must be aware of PEIR and document the treatment chosen with long term follow-up to support further investigation into this entity.

References

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K.P. Counihan *, A.C. O'Connell **

* Department of Paediatric Dentistry, Leeds Dental Institute, Clarendon Way, Leeds, LS2 9LU

** Division of Public and Child Dental Health, Dublin Dental University Hospital, Lincoln Place, Dublin 2, Ireland

Postal address: Dr. K. Counihan, Department of Paediatric Dentistry, Leeds Dental Institute, Clarendon Way, Leeds, LS2 9LU.

Email: katepcounihan@gmail.com
Table 1. Summary of PEIR prevalence and teeth most commonly affected

Author,
Type of Study        Assessment               Incidence & Prevalence

Seow, Wan, McAllan   1,959 Bitewing           Subject prevalence 6%
Prospective          934 male, 1025 female    Tooth prevalence 2%
Australia 1999 a     Mean age 7.8 years
                     (+/- 1.79 years)

Seow, Lu, McAllan    1281 OPT's               Subject prevalence 3%
Prospective          11,767 unerupted teeth   Tooth prevalence 0.5%
Australia 1999 b     610 male, 671 female
                     Mean age 5.1 years,
                     9.7 years, 17.3 years

Nik, Rahman          1,007 OPTs,              Subject prevalence 27.3%
Retrospective        497 male, 510 female     Tooth prevalence 2.1%
Malaysia 2003

Ozden and Acikgoz    9,750 OPT's              Subject prevalence 1.55%
Retrospective        2,922 unerupted teeth    Tooth prevalence 0.95%
Turkey 2009          Mean age 47.81 years
                     (range 14-73)

Author,
Type of Study        Teeth Commonly Affected

Seow, Wan, McAllan   Mandibular 1st molar (4%)
Prospective          Mandibular 1st premolar (2%)
Australia 1999 a

Seow, Lu, McAllan    Maxillary 1st molar (4%)
Prospective          Mandibular 1st molar (3%)
Australia 1999 b

Nik, Rahman          Maxillary 1st premolar (5.1%)
Retrospective        Maxillary 2nd premolar (3.9%)
Malaysia 2003        Maxillary first molar (3.7%)

Ozden and Acikgoz    Mandibular 2nd molar (9.5%)
Retrospective        Maxillary 2nd premolar (4.7%)
Turkey 2009

Table 2. Case reports and teeth affected by PEIR since 2004

                                Mandibular Teeth

Author/Year                M1   M2   M3   PM1   PM2

Moskovitz and Holan 2004        1
Davidovich et al. 2005          1
Klambani et al. 2005            1
McEntire et al. 2005                             1
Hata et al. 2007 *                               1
Yamana 2010                1
Counihan and O'Connell     1    1                1
  (current study)

* PEIR also in maxillary central incisor and
mandibular lateral incisor in the same patient.

Table 3. Intervention provided and
outcomes for teeth affected with PEIR

Author,         Patient Age/
Type of Study   Tooth affected               Outcome

Moskovitz and   6yrs 2mo, Mand 2nd molar     Monitored pre-eruptively
Holan 2004                                   for 5 years,
                                             Restoration on eruption
                                             aged 11yrs 4mo.

Davidovich et   11yrs, Mand 2nd molar        Surgical access of
al 2005                                      unerupted tooth for
                                             restoration with partial
                                             pulpotomy and amalgam.
                                             Successful after 6 months

Klambani 2005   9yrs, Mand 2nd molar         Monitored pre-eruptively
                                             for 2 years. The lesion
                                             increased in size.
                                             Extraction on eruption
                                             (due to pain)

McEntire et     9 yrs, Mand 2nd premolar     Erupted and restored.
al. 2005                                     Successful after 5 yrs

Hata et         8 yrs 6mo, Max central       Erupted and restored
al. 2007        incisor

                Mand Lateral incisor, Mand   Successful 18 mo - 5 yrs
                2nd premolar

Yamana 2010     5yr 10mo, Mand 1st molar     Restored (post-eruption)

Counihan and    10 years, Mand 2nd PM        Monitored and restored on
O'Connell                                    eruption Successful after
                                             6 yrs

                6 Yrs, Mand 1st molar        Fissure seal on eruption,
                                             Monitor radiographically 5
                                             yrs

                12 yr, Mand 2nd molar        Cusp fracture and restore
                                             5yrs 2 mo Extracted
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