A rare report of mandibular facial talon cusp and its management.

Talon cusp is an uncommon dental anomaly showing morphologically well delineated, accessory cusp-like structure projecting from cingulum to the incisal edge of anterior teeth. This anomaly is rare in the mandibular dentition and rarer on the facial aspect. A case of this infrequent entity of mandibular facial talon cusp and its management is reported here.

INTRODUCTION

Talon cusp is an uncommon dental anomaly showing morphologically well delineated, accessory cusp-like structure projecting from cingulum to the cutting edge. It was named as talon cusp due to its appearance as eagle's talon when viewed from incisal edge.[1] Outfolding of the enamel organ or hyperactivity of the dental lamina during morphodifferentiation stage of tooth development or hyperproductivity of the anterior ends of dental lamina could be the cause for morphological variation in the crown and root, whereas talon cusp on labial surface of the tooth is attributed to the hyperplasia of labial central developmental lobe.[234] However, the etiology of talon cusp is not well understood, but is proposed to be a combination of genetic and environmental factors.[12] Disturbances during morphodifferentiation, such as altered endocrine function, might affect the shape and size of tooth without impairing the function of ameloblasts and odontoblasts.[5] Talon cusp may be associated with genetic factors and it has been reported in twins,[6] siblings[578] and also children of consanguineous marriages.[2] It has also been reported in a family with father and child exhibiting in permanent and primary dentitions, respectively.[9] The talon cusp can be considered as one end of a range of hyperactivity of the dental lamina, with macrodontia and double tooth in the middle while supernumerary tooth on the other end.[10] It was also reported in association with syndromes,[11] such as Mohr syndrome (Orofacial digital II), Incontinenta pigmentii Achromians, Ellis van creveld syndrome, Struge Weber syndrome (Encephalo-trigeminal angiomatosis), Rubinstein Taybi syndrome,[1112] and Alagille's syndrome.[13]

The other proposed names for talon cusp are accessory cusp, addition cusp, anterior dens evaginatus, cusp-like hyperplasia, exaggerated cingulum, prominent accessory cusp like structure, supernumerary cusp, interstitial cusp, tuberculated premolar, odontoma of the axial core type, evaginated odontoma, occlusal enamel pearl, occlusal anomalous tubercle.[311]

This anomaly has been reported to be unusual in the mandibular dentition and rare on the facial aspect. To the best of our knowledge, only four cases[11151617] Table 1 have been reported in the literature and a rare case of fusion of the mandibular permanent incisors with labial and lingual talon cusps was also reported.[14]

Table 1

Benefits and risks in a clinical trial

The presence of this anomaly is not always an indication for dental treatment unless it is associated with clinical problem. The complications of talon cusp are diagnostic (if unerupted, resembles supernumerary, or compound odontomes), functional (occlusal interferences, trauma to lip and tongue, speech problems, and displacement of teeth), pathological (caries, abrasion, accidental cusp fracture, apical periodontitis, and periodontal diseases due to plaque accumulation in the grooves), and esthetics.[191118192021] The purpose of the present report is to emphasize the rarity of mandibular facial talon and treatment options for good prognosis.

CASE REPORT

A 7-year-old south-Indian boy reported to the department of Pedodontics and preventive dentistry with a chief complaint of extra tooth in the lower jaw. Past medical, dental, and family histories were not relevant. Clinical examination, a cusp-like projection on the permanent right mandibular lateral incisor was evident [Figure 1a and b], which was confirmed as talon cusp on obtaining mandibular anterior occlusal radiograph that revealed an inverted “V”-shaped radio opaque projection extending from the cemento-enamel junction, a pulp horn overlapping pulp chamber and, an open tooth apex [Figure 1c]. The gingiva around the tooth was healthy and the talon was 7 mm in length cervico-incisally, 4.5 mm mesiodistally, and 4 mm anterio-posteriorly at its prominence. Talon cusp was conical in shape, curved towards the incisal edge when viewed laterally with deep groove between the talon and the tooth surface [Figure 1b].

Figure 1

Talon on right mandibular lateral incisor (initial visit) (a) labial view (b) lateral view (c) anterior occlusal radiograph

As the talon cusp was larger, esthetically unpleasant and occlusally interfering with upper right lateral incisor, periodic gradual reduction (lateral grinding) of talon, and subsequent topical fluoride application was planned at every 45 days (between June 2012-December 2012).

After obtaining the informed consent from the child's parent, oral prophylaxis was performed and the bulk of talon cusp was reduced in two planes by merging the borders with the tooth surface using a tapered fissure bur (Mani DIA-BURS®, Prime Dental Products Pvt. Ltd, India) under strict isolation. Half the thickness of enamel was reduced in the first visit and the surface was polished with composite finishing discs (Super-Snap®, Rainbow technique kit, Shofu, USA) and fluoride varnish (Bifluorid 12®, VOCO, Germany) was coated over the surface to reduce sensitivity and stimulate reparative dentine formation for pulp protection. During 2nd visit, entire enamel thickness was removed and similar procedure was followed in the subsequent two visits to reduce the dentin thickness [Figure 2a and b] and composite resin restoration (Tetric N-Ceram, Ivoclar Vivadent, USA) was placed over the labial surface during the fifth visit. [Figure 2d]. The patient was reviewed for a period of 12 months, after treatment [Figure 3a and b].

Figure 2

Talon on right mandibular lateral incisor (fifth visit) (a) labial view (b) lateral view (c) anterior occlusal radiograph (d) intraoral periapical radiograph

Figure 3

Talon on right mandibular lateral incisor (1-year follow-up visit) (a) labial view (b) in occlusion (c) anterior occlusal radiograph

Pulpal status and root development were evaluated by obtaining periodical mandibular anterior occlusal radiograph during 2nd, 5th, and 12-month follow-up visits [Figures 2c and 3c]. At the end of 1-year follow-up, root growth was evident with bifid root canals, without any complications. [Figure 2d and 3c]

DISCUSSION

Talon cusps occur most commonly on the permanent incisors, with more than 90% of them in maxilla and predominantly on permanent maxillary lateral (55%) or central incisors (33%) and less frequently on mandibular incisors (6%) and maxillary canine (4%).[3] The prevalence of talon cusp ranges from 0.06% to 10%,[222324252627] with male predilection.[239] Higher incidence was noted in Chinese and Arab populations than Caucasians and Negroes.[39]

Hattab[2] classified this anomaly as type 1 (talon), type 2 (semi talon), and type 3 (trace talon). Hsu Chin-Ying et al., modified this as major, minor, and trace talon.[28] When viewed from incisal aspect, the morphology appear as either “T,” “Y,” or “π” shape for major, minor, or bifid talon cusp.[29] The presented talon is type 1 or major with a T-shaped outline.

Radiographically, major and minor talon appear typically as “V”-shaped radio-opaque structure superimposing over the normal image of the tooth, whereas tubercle-like and trace talon may not be detected in radiograph. This appearance varies with location, size, and shape of the cusp and the angle at which radiograph is taken. The point of “V” is inverted in mandibular teeth[11] as it is composed of enamel, dentin, and varying amount of pulp tissue as in the present case [Figure 1c]. Due to the superimposition over the main pulp chamber, it is difficult to determine the extent of pulpal extension and is debatable over the extension of pulp in the cusp[230] or not.[31] However, it has been proposed that major talon cusps, especially that deviate from the tooth crown are more likely to contain pulp as in the present case. Due to large pulp chamber in the young permanent teeth, the periodic lateral grinding should be performed with utmost care and also complete reduction of talon cusp (major) should not be done. The formation of reparative dentin varies with the operative procedure and was reported around 2.8 μm and 1.5 μm per day for primary and permanent teeth, respectively.[32] Reparative dentin is usually formed when teeth are mechanically prepared to within 1.5 mm of the pulp and it takes around 15 days for the formation of new odontoblasts from pulpal undifferentiated mesenchymal cells and 30 days for microscopic appearance of reparative dentin.[33] In the present case, periodiclateral grinding was done at every 45 days, over a period of 7 months to preserve pulp vitality and minimize sensitivity. Fluoride varnish was applied over the ground tooth surface to prevent post operative sensitivity. The root growth was evident at 12-month follow-up, without any complications. The root was bifid, which is much similar to that of crown and probing the point that morphodifferentiation stage would have been affected during the formation of crown as well as root. Shey and Eytel were the first to report periodic grinding method by reducing the entire bulk along the surface rather than only involving the tip for enhanced formation of reparative dentin.[34] Similar method was reported, on permanent maxillary central incisor without any root abnormalities, every 45 days, over a period of 9 months.[1819]

Early diagnosis and definitive treatment is necessary to prevent complications and periodic lateral grinding of mandibular facial talon was done in the present case, so that the erupting maxillary right permanent lateral incisor would not have any occlusal interference [Figure 3b]. The other treatment options were simple prophylactic measures such as fissure sealants or composite restorations,[11] total cusp reduction followed by calcium hydroxide/mineral trioxide aggregate pulpotomy[35] root canal treatment,[235] extraction followed by orthodontic correction and prosthetic rehabilitation.[15]

CONCLUSION

Though, mandibular facial talon is rare to encounter in dental practice, proper diagnosis is mandatory before appropriate treatment is planned. However, the management and treatment depend upon size, complications and patient's compliance. Role of pediatric dentist is utmost important in early diagnosis to minimize or prevent complications associated with it.