An unusual morphological anomaly in an incisor crown. Anterior dens evaginatus 

LLENA-PUY MC, FORNER-NAVARRO L. AN UNUSUAL MORPHOLOGICAL ANOMALY IN AN INCISOR CROWN. ANTERIOR DENS EVAGINATUS. MED ORAL PATOL ORAL CIR BUCAL 2005;10:13-6.

ABSTRACT

Exophytic growth of a portion of the tissue structure is one of the various clinical manifestations of the morphological anomalies that can affect the crown of the anterior teeth. The crown form disorder presented in this paper consists of an asymptomatic bulge on part of the vestibular surface of the tooth, due to enamel and dentine growth, with no radiological evidence of the pulp having extended into the protrusion of mineralised tissues. In this case, it only affects one tooth and is not associated with any other dental morphology or structure disorder, or with any of the syndromes that have been described in association with this anomaly. The term to describe this situation in the anterior teeth is not clearly defined in the relevant literature, which employs various names such as talon cusp, accentuated cingulum (when it affects the lingual or palatal surface) or dens evaginatus (evaginated tooth, evaginated odontome), the term that is always used when it is present in the posterior teeth.

Key words: Dental anomaly, enamel. talon cusp, dens evaginatus.

 

INTRODUCTION

Dental morphology anomalies can be classified according to the group of teeth (incisors, canines, premolars or molars) in which they occur, as each group presents characteristic alterations (1, 2). The majority of pathological variations in shape affect the crown of the tooth. Some are relatively frequent while others are less prevalent or may only affect specific ethnic groups (3). One of the rare anomalies is the protrusion of dental tissues and although various names have been employed, as discussed below, its characteristics correspond to those of evaginated teeth. This paper presents a clinical case of this morphological disorder affecting the crown of a anterior tooth. Given its rarity, a differential diagnosis to distinguish it from similar morphological anomalies is presented and the specific nomenclature for this condition is reviewed.

CLINICAL REPORT

The patient, a 13 year old male, visited a Preventive Dentistry Area Unit (Valencian Health Service) clinic for a routine oral health check. As a result of the clinical examination, an alteration in the shape of the mandibular left lateral incisor was detected, consisting of an enlargement of the mesial half of the vestibular surface of this tooth with no development grooves separating the protuberance from the rest of the tooth. There was no other alteration, either in structure or colour, of the affected surface or of the rest of the tooth (fig. 1). The visual examination revealed no other pathological alteration of the remaining incisors or the other teeth in the mouth. The radiography of the affected tooth (fig. 2) shows a growth in the enamel, clearly visible in the vestibular-lingual view; the characteristic radio-opacity of the dentine can be seen under the enamel but no associated pulp alteration or pulp extension into the interior of the protuberance of mineralised dental tissues is visible.

DISCUSSION

Other congenital disorders that affect dental development cause clinical manifestations in the shape or size of the tooth or even produce peculiar alterations, such as double tooth (4), which also present changes in the normal shape of the crown. The X-ray image of this case is very similar to that of another morphological alteration which is characteristic of the anterior teeth (incisors and canines): accentuated cingulum (1). This anomaly consists of an excessive growth of the cingulum that causes it to resemble a cusp. As in any cusp protuberance, its structure is composed of dentine with a covering of enamel, although its interior may contain a certain amount of pulp tissue. However, accentuated cingulum occurs on the lingual or palatal surfaces of the anterior teeth, providing a differential diagnosis from the case under discussion despite the similarity of the X-ray image. Vertical crestae (rugae adamantineae) (1) are a rare coronal morphology disorder that affect the vestibular surface of the incisors, as in the case described in this paper, but their defining feature is a ridge of enamel that crosses the centre of the vestibular surface of the tooth in a cervical-incisal direction. Tubercles also bear a resemblance to the case in question. The best known is the Carabelli tubercle (5), which affects the mesial half of the palatal surface of the maxillary permanent molars. These protrusions, which are less frequent on the vestibular surfaces, may be sufficiently emergent to form grooves that separate them from the rest of the coronal surface. However, the tubercles described only occur in the posterior teeth. A more marked variant are accessory cusps. These lead to anomalous tooth crown shapes, causing ‘molarisation’ of the premolars (1) or a distorted crown form in the molars. Double tooth (4) could also be mistaken for the case in question, as this condition presents a crown of increased size, whether due to the joining of two teeth (normal or hyperodontia), known as dental fusion, or to an attempted duplication of the tooth (schizodontia or gemination). Nonetheless, this enlargement takes place in a mesial-distal direction and the appearance of the crown is that of two crowns joined together, which is not the case here. The last condition that should be considered in a differential diagnosis is dens evaginatus, where the verrucose protuberance on the occlusal surface of the affected teeth may be composed of enamel, enamel and dentine or even enamel, dentine and a small extension of the pulp tissue. However, this is a term that is usually employed for the posterior teeth (6).

A review of the literature concerning cases similar to the one presented in this paper shows a lack of agreement in the definitions of some of the dental form anomalies. One of the first terminological difficulties is that, rather than Pindborg’s classic term (1) for the anomalous development of the cingulum of the anterior teeth, some authors (7, 8) employ the term talon cusp to describe the same condition. A case resembling the one described in this paper, an asymptomatic black girl with a pyramid-shaped coronal protrusion on the vestibular surface of the maxillary central right incisor, from the anatomical neck of the tooth almost to the incisal edge, was classed as facial talon cusp (9). Other cases labelled as talon cusp with vestibular presentation have been described in both arches of permanent teeth in both sexes (10). Talon cusps have also been described on the vestibular and palatal surfaces of the same tooth (11). Talon cusp is most frequent in patients with syndromes such as those of Rubinstein-Taybi (12), Mohr (13), Sturge-Weber (14), Ellis-van Creveld (15) and Bloch-Sulzberger (16).

Another confusion (or, at least, imprecision or ambivalence) is found in the case of dens evaginatus (evaginated tooth, evaginated odontome). Some authors use the term dens evaginatus (17) to conditions that others describe as accentuated cingulum or talon cusp (18), with specific reference to growths in the cingulum area (therefore palatal), as in the case of a central maxillary incisor described by these authors. Others, however, consider both clinical conditions to be variations of what may be termed ‘accessory cusps’ (7, 8). In essence, dens evaginatus is generally defined as a dental development anomaly that causes a protuberance of the dental tissue(s) on the occlusal surface of the crown (6), consequently on the rear teeth. However, references may also be found to this condition in both the anterior and the posterior teeth, although affecting the lingual or palatal surface of the anterior teeth (19).

In conclusion, the case described in this paper is an asymptomatic dental anomaly that has not caused any other alteration to the tooth or the arch. It is confined to the dental form and neither the structure nor the colour are affected. It is the result of an anomalous development of the enamel, and probably of the underlying dentine, and presents specific features that characterise it and differentiate it from other coronal morphology anomalies. Nonetheless, in view of the diversity of the terminology, we consider that it should be classed as anterior dens evaginatus with vestibular presentation: the protrusion of the coronal dental tissues does not differ from the condition usually labelled as (posterior) dens evaginatus and we believe that the same terminology should be used for the same structural alteration, although an indication of the position of the anomaly may be added to distinguish anterior from posterior and even, in the case of the anterior teeth, to indicate lingual/palatal or vestibular, given the rarity of the latter case.

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