Sturge-Weber syndrome

Talon cusp is an uncommon developmental anomaly affecting the anterior teeth, characterized by cusp-like projections, usually presenting on the lingual surface of the affected tooth. The occurrence ranges from 0.73% to 8% of the population. Talon cusp has been associated with other dental anomalies such as dens invaginatus, odontomas, and impacted teeth; associations with somatic anomalies such as Mohr's, Rubenstein-Taybi, and Sturge-Weber syndromes have also been reported. Only a few cases of labial talon cusp have been reported and only one previously published report exists documenting talons appearing both labially and lingually on the same tooth. This study reports the unusual case of a 10-year-old girl with bilateral talon cusps and one tooth possessing both lingual and labial talons. The lingual talon on the right maxillary lateral incisor was interfering with normal occlusion and was responsible for labioversion of the tooth. Treatment options were presented.

Introduction

Talon cusp is an uncommon dental developmental anomaly characterized by accessory cusp-like projections of the teeth. The projections may be subtle but may also be significant enough to complicate occlusion, or if located on the facial aspect of anterior teeth, a significant dental cosmetic situation may result. This anomaly has been named talon cusp because the projections often resemble an eagle's talon.1 Most reported cases of talon cusp are located in the permanent dentition.2-4 The permanent maxillary lateral incisor is the most commonly affected tooth with 55% of reports published in the literature. Maxillary central incisors have been identified in 33% of all reported cases.5 Less frequently, mandibular incisors (6%) are involved.4 In the vast majority of cases, the talon cusp is observed on the lingual surface of the tooth characterized as a projection emerging from the cingulum extending to the incisai edge.6 Because the term talon cusp has been used to loosely describe many different cusp-like aberrations in anterior teeth, attempts have been made to categorize the degree of severity of the condition.2 Some reports suggested that the tenu talon cusp be reserved to those cusps with a projection of at least 1 mm7 or in cases in which the cusp extends at least one-half the distance from the cementoenamel junction to the incisai edge.8

Mitchell9 first described the talon cusp in 1892, but most reports have been published in the last 30 years. Hattab et al.2 reported a male-female ratio of 47:26 among 73 cases reported in the literature. Davis and Brook10 reported a male:female incidence ratio of 32:18. Extensive prevalence studies have not been performed, but it is estimated that the frequency of talon cusp may range from 1% to 8% of the population.4,5 However, observations of the occurrence of talon cusps among Chinese11 and Arab12 populations suggest that the condition may be more common in certain ethnic groups. Talon cusp is a term usually confined to anterior teeth. Dens evaginitus is preferred when describing posterior teeth with additional cusp-like projections. Dens evaginitus is reported to be higher in Asians, American Indians, and Eskimos.6 The lack of precise criteria to accurately define talon cusp has made documentation of the actual prevalence difficult.

Talon cusp has been reported as an individual dental abnormality6 but also in association with other dental anomalies2,13-15 (e.g., supernumerary teeth, odontomas, impacted teeth, pegshaped lateral incisors, dens invaginitus, posterior dens evaginitus). Although talon cusp is not documented as an important part of any specific syndrome, there appears to be an increased incidence of the condition in patients with Mohr,16 RubinsteinTaybi,17 and Sturge-Weber syndromes.11 In isolated cases, identical talon cusps have been documented in twins, suggesting a genetic influence.4

The etiology of talon cusp is poorly understood. It has been suggested that the condition may have a multifactorial etiology to include both genetic and environmental factors.18 Hyperactivity of the dental lamina early in odontogenesis has been suggested as a factor. Hattab et al.2 suggested that the aberrant cusp might be formed as a result of an outward folding of the inner enamel epithelial cells and a transient focal hyperplasia of the mesenchymal dental papilla. Gungor et al.19 reported a composition of normal enamel and dentin with varying extensions of pulpal tissue into the talon projection.

Talon cusps have been defined as cusp-like projections occurring exclusively on the palatal or lingual surface of teeth.20 Although very rare, two cases have been reported documenting talon cusps on the labial surface of maxillary permanent central incisors,21,22 and only one case has been reported where a facial and lingual talon cusp have occurred on the same tooth.3 The following case describes the second reported case of a facial and lingual talon cusp on the same tooth and the bilateral occurrence of a lingual talon cusp on the antimeric permanent maxillary lateral incisor.

Case Report

A 10-year-old girl presented to the dental clinic for a routine dental examination. The patient was concerned about the size of her maxillary right lateral incisor (no. 10), stating that it seemed to be larger than the antimere lateral incisor (no. 7), and that the tooth had an unusual ridge on the back of it (Fig. 1). The crown of tooth 10 was approximately 1 mm wider than tooth 7, which also had a talon cusp located on the lingual surface. Clinical inspection revealed bilateral talon cusps on the permanent maxillary lateral incisors: tooth 10 had talon cusps on both the facial and lingual surfaces and tooth 7 possessed a talon cusp on only the lingual aspect. A clinical diagnosis of bilateral talon cusp was made. The patient had received regular dental treatment from several dentists over the past 3 years, but her dental anomaly was never mentioned by any of the previous providers.

Percussion, palpation, and thermal challenge tests were all within normal limits. The patient's medical and family history were noncontributory. No dental caries or irritation of the soft tissues was observed. Occlusal interference was present on tooth 10, resulting in labioversion of the lateral incisor. Apart from the slight width disparity, the patient did not have an esthetic complaint. The patient and her parents were given several treatment options, which included odontoplasty of the larger lateral incisor to reduce the mesiodistal width and remove the lingual interference with subsequent resin-based composite bonding on the labial surface to establish a smoother, uninterrupted facial surface of the tooth. Some risk would be involved with this procedure, as pulpal extensions into the talon cusp are not uncommon. The second option was referral to the orthodontist to move teeth into the desired positions to eliminate the interference from the lingual talon cusp and then reconsider odontoplasty if esthetic and functional demands were not completely met. The third option was to do nothing, but the patient and her parents were advised that the premature contact on the lingual surface of tooth 10 might predispose the tooth to increase, damaging occlusal forces. The patient and her parents opted for orthodontic consultation.

Discussion

Although talon cusp is a rare finding, it has clinical significance because these teeth often possess deep grooves in the areas where the cusp-like prominence is located, predisposing the patient to caries. Furthermore, the talons often contain extensions of pulp tissue similar to pulp horns.20 Radiographically, the length of the extension may be unclear because it may be superimposed over the main pulp chamber. Because of this, great care is necessary when operative procedures are undertaken to remove caries or when reduction of the talon cusp is considered to relieve the occlusal interference.3

The mere presence of a talon cusp does not warrant endodontic or restorative treatment unless other dental problems are associated with it such as caries, periodontal loss of attachment, occlusal interference, labial displacement of the tooth, or compromised esthetics.8,10,21 In the case of talon cusp reduction to remove occlusal interference, gradual, periodic cusp reduction has been suggested.21,23 This gradual reduction technique may encourage the development of reparative dentin and pulp obliteration within the extension. Others have advocated total removal of the talon cusp, especially if the interference is severe, exposing the pulpal extension and necessitating pulp therapy.3 In the case of an immature apex, the preferred method of treatment would be vital pulp therapy to allow for continued apical development.24

Conclusion

A case of bilateral talon cusp involving the permanent maxillary lateral incisors was presented. One of the involved teeth presented with both facial and lingual talons, an extremely rare occurrence, which has been reported only once previously in the literature. Talon cusps may be associated with somatic abnormalities, such as Mohr's syndrome, Rubenstein-Taybi syndrome, and Sturge-Weber syndrome, and other odontogenic anomalies, such as supernumerary teeth, odontomas, and impacted teeth. Recognition is important to establish proper treatment.25 Clinicians should be aware that the prominent talons often possess deep developmental grooves that may be carious and that pulpal extensions in the talon may limit the extent of operative procedures.

References

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22. Tsutsumi T, Oguchi H: Labial talon cusp in a child with incontinentia pigment! achromians: case report. PediatrDent 1991; 13: 236-7.

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Guarantor: Lt Col William Jackson Dunn, USAF DC

Contributor: Lt Col William Jackson Dunn, USAF DC

Director of Research and Biomaterials, Lackland Air Force Base, TX 78236-5551.

This manuscript was received for review in January 2003, The revised manuscript was accepted for publication in May 2003.

Copyright Association of Military Surgeons of the United States Feb 2004
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