Abstract

Radiographic signs, detectable on an Developmental malformation of the teeth has a wide and complex spectrum, making exact diagnosis sometime difficult. The radicular invaginatus is one of a such entity. Owing to its unusual radiographic appearance, such teeth are often incorrectly diagnosed as a double root, a radicular invagination or fused teeth. These are described as severe variants of dens invaginatus. The anomaly typically occurs during the stage of tooth development of odontogenesis. The exact aetiology is unknown. A case is reported of a radicular invaginatus associated with dentigerous cyst.

Introduction

Clinical Relevance

Dens invaginatus is a rare anomaly, clinically present in varied forms of disturbed morphology. Where these entities occur, they should be noted and addressed. The literature documents very few reported cases of radicular invaginatus associated with dentigerous cyst. Proper examination and radiographic investigation are essential to make a conclusive diagnosis.

Radicular invaginatus is an extremely rare developmental malformation representing as a severe variant of dens invaginatus. This malformation is the result of an infolding of the enamel epithelium during odontogenesis. Two main variants of dens invaginatus are described, coronal and radicular. Hallet was the first to put forward the classification of dens invaginatus but most widely used classification is suggested by Oehlers. Etiopathogenesis of dens invaginatus is thought to be either genetic or mechanical. Mechanical factors included trauma and/or infection1, 2, 3. A recent hypothesis proposes dental invagination as a consequence of the degeneration of the dental lamina which can lead to fusion, gemination or agenesis4, 5, 6, 7.

Most common teeth involved are upper lateral incisors, other teeth affected less commonly are upper maxillary canine and central incisors and rarely mandibular teeth2, 3, 5.
This paper presents a rare case of dentigerous cyst arising from radicular invaginatus involving right maxillary lateral incisor.

Case Report

A 11-year-old girl was referred to oral and maxillofacial clinic for the management of the cystic lesion in the right anterior maxillary region by her orthodontist. She was medically fit and well and was accompanied by her both parents during her consultation visit.

Patient was asymptomatic and on examination there was buccal expansion in the region of right upper lateral incisor (Fig 1). On palpation, eggshell crackling was felt while pressing in the buccal sulcus in the region of upper lateral incisor, suggestive of a cystic lesion. The right upper canine was unerupted, and upper lateral incisor was partially erupted, mesially inclined and retained upper deciduous canine.

Orthopantomogram and CBCT brought by patient revealed a radiolucency associated with right upper lateral incisor with abnormal tooth morphology with external teat extending into radiolucency (Fig 2). CBCT confirmed a radiolucency measuring 2cm Height x 1.7cm Width and 2.2cm Depth associated with malformed upper right lateral incisor consistent to radicular dens invaginatus (Fig 3a,b). 3D reconstruction of upper lateral incisor confirmed radicular invaginatus showing malformation crossing cementoenamel junction and apex of the tooth (Fig 4). Upper right canine was impacted in favourable situation to erupt and there was retained upper right deciduous canine. Patient brought an orthopantomogram taken during 2019 revealing radiolucency around malformed upper lateral incisor (Fig 5).

Based on clinical and radiographic finding a diagnosis of dentigerous cyst associated with upper right lateral incisor was established. Aspiration biopsy was offered during examination, but the patient was anxious, and parents did not consent to do along chair side. Surgical exploration of the lesion was consented by parents under general anaesthetics.

The aspiration revealed straw coloured fluid and cyst was enucleated and sent for histological examination. Upper right deciduous canine was removed.

Post-operative phase was uneventful, and patient recovered very well (Fig 6). Histopathological findings revealed collapsed cyst lined in most part with non-specific, non-keratinising consistent to dentigerous cyst.

Figure 1: Intraoral photograph showing buccal expansion in upper right lateral incisor.

Figure 2: Orthopantomogram showing well demarcated radiolucency involving radicular part of invaginatus has increased in size at presentation.

Figure 3a: CBCT showing size of cystic lesion in axial, sagittal and coronal views.

Figure 3b: CBCT showing size of cystic lesion in axial, sagittal and coronal views.

Discussion

Dens invaginatus is an anomaly presented with a widely varied morphology. It has also been referred to as dens in dente, dilated/invaginated composite odontoma, gestant odontoma, tooth inclusion etc. Hallet1 was first to introduce the term “dens invaginatus” and classified them in to various types based on coronal and radicular invaginations. The most widely used classification in the literature was given by Oehler3 in 1957 describing dens invaginatus in three different forms ranging from type 1, anomaly limited within the crown of the tooth, type 2, invagination extending apically past the cemento-enamel junction, but remains within root and lastly type 3 where invagination perforates apically to create an apical or periodontal foramen. The most severe form, type 3, also known as dilated odontoma, the tooth is usually bulbous and malformed. Unfortunately, dilated odontome are not represented in any of the classifications as an entity but are categorised as a severe form of dens invaginatus. Dens invaginatus can affect both primary and permanent teeth and its prevalence is reported to be 1.7 to 10%. Males are more affected by a ratio of 3:16. All the published studies have shown that the maxillary lateral incisors were the most commonly affected teeth, followed in descending order by permanent central incisors, canines and molars7, 8, 9.

Development of an invaginated tooth has been explained based on a number of theories in the last 75 years including: growth pressure on dental arches resulting in buckling of the enamel leading to invagination, failure of internal epithelium growth, rapid proliferation of internal enamel epithelium, distortion of enamel organ during development, infection and/or trauma, and incomplete fusion of two tooth germs or to the attempted division of a single tooth germ8, 9. The genetic and syndromic association with dens invaginatus has always been debated upon without much clinical evidence available so far10, 11, 12.

The most significant clinical concern of dens invaginatus is the risk of developing pulpal pathology13, 14. The invagination commonly communicates with the oral cavity, allowing the entry of irritants and microorganisms directly into the pulpal tissue.

Conclusion

Dens invaginatus lesions are commonly seen under palatal cusp tips as pits. There may be an extensive involvement of tooth structure resulting in grossly distorted morphology is rare as seen in this case. Proper examination and radiographic investigation are essential to conclude the diagnosis.

Abbrevations

SC: Standard coronectomy MC: Modified coronectomy IAC/N: Inferior Alveolar canal/Nerve LN: Lingual Nerve OPG: Orthopantomogram CBCT: Cone Beam CT scan