An Unusual Presentation of Mesiodens Tooth with Talon Cusp – Report of Four Cases and Literature Review

Talon cusp is an uncommon developmental anomaly of the tooth shape, characterized by an accessory cusp-like structure, projecting from the cingulum area or cemento-enamel junction of the maxillary or mandibular anterior teeth (Hattab et al., 1995). It is observed more frequently among males than females, and it occurs either unilaterally or bilaterally (de Saousa et al., 1999). There are insufficient epidemiological data regarding the true prevalence of this dental abnormality, and the frequency may vary with age, race and criteria used to define this anomaly (Buanviaje and Rapp 1984, Sedano et al., 1989, Chen and Chen 1986, Chawla et al., 1983).


Introduction
Talon cusp is an uncommon developmental anomaly of the tooth shape, characterized by an accessory cusp-like structure, projecting from the cingulum area or cemento-enamel junction of the maxillary or mandibular anterior teeth (Hattab et al., 1995).It is observed more frequently among males than females, and it occurs either unilaterally or bilaterally (de Saousa et al., 1999).There are insufficient epidemiological data regarding the true prevalence of this dental abnormality, and the frequency may vary with age, race and criteria used to define this anomaly (Buanviaje andRapp 1984, Sedano et al., 1989, Chen and Chen 1986, Chawla et al., 1983).(Mader 1981), and primary maxillary incisors (Chen and Chen 1986, Henderson 1977).Occurrence of talon cusp in supernumerary teeth is a rare dental phenomenon, and there have been few reported cases of talon cusp occurring on facial surface (Topaloglu et al 2008, Siraci et al 2006).The purpose of this article is to present four Indian patients with talon cusps which developed on the facial surface of the mesiodens in the maxillary arch.

Case Reports
Intra oral examination in three Indian patients, who reported to outpatient Department of Pedodontics and Preventive Dentistry, exhibited talon cusp on the facial surface of mesiodens (Fig. 1, 2, 3 and 4).The affected patients included two girls and two boys aged between 5 years to 13 years.All four patients were in good general health.The first patient had complete permanent dentition; the second and third patient exhibited mixed dentition; and the fourth patient showed primary dentition.The detailed description of these patients associated with mesiodens tooth and talon cusps is presented in Table 1.

Discussion
The occurrence of both supernumerary and dens evaginatus is an interesting dental anomaly with which every clinician should have knowledge for an accurate diagnosis and a correct treatment.The exact cause behind the development of both supernumerary tooth and talon cusp is not clearly stated.It is attributed to the hyper production of the dental components from the dental lamina that is more common in the maxillary anterior region (Salama et al 1990).Previous published literature suggests that 75% of the talon cusps have been found in permanent incisors (lateral incisors followed by central incisors and canines), and the occurrence of talon in supernumerary tooth like mesiodens is an uncommon finding.According to literature search till date, only twelve cases of talon cusp occurring in supernumerary tooth have been reported (Table 2)   Therefore, the development of talon on the facial aspect of a supernumerary tooth further constitutes a rarer entity.In all our cases, talon cusps were found on the facial surface of mesiodens teeth thereby being an extremely rare occurrence.
Jowharji et al (1992) commented on facial talon anomaly and suggested that an alteration to the conventional definition of talon cusps be made; taking into consideration that talon cusp may be found on the facial aspect of teeth.However, they (Jowharji et al 1992)  the incisor group and be extended to include the facial aspect too.According to these authors' opinion and from our cases, we strongly recommend, for a better understanding of this condition, that the definition should be further extended to include the mesiodens tooth.Hattab et al (1996) have classified the talon cusps into three types based on the degree of formation and extension.Type 1 talon refers to a morphologically well-delineated additional cusp that prominently projects from the palatal surface of a primary or permanent anterior tooth, and extends at least half the distance from the CEJ to the incisal edge.Type 2 talon is an additional cusp of a millimeter or more, extending less than half the distance from CEJ to the incisal edge.It may blend with the palatal surface or stand away from the rest of the crown.And type 3 is enlarged or prominent cingula and their variations, i.e., conical, bifid, or tubercle like.The same classification can be employed in classifying the facial talon cusps too.Therefore, based on this classification, our reported cases were categorized as type 3 Talon cusp in first case as the talon appeared like a small tubercle.In second, third and fourth case, the talon extended more than half distance from the CEJ to the incisal edge.Hence they were classified as type 1 talon. .Supernumerary teeth in the primary dentition are usually normal or conical in shape.In the permanent dentition, they show great variation in morphology.Primosch (1981) classified them into supplemental or eumorphic and rudimentary or dysmorphic types (conical, tuberculate and molariform), according to their shapes.According to Koch et al in (1986), supernumerary teeth may be classified as 56% conical, 12% tuberculate, 11% supplemental, and 12% other configurations.Recently, Nagaveni et al (2010) presented a new form of mesiodens (multi-lobed mesiodens) associated with a palatal talon.In the presented four cases, the mesiodens tooth was classified as conical type based on the above classification.
Treatment modality for talon cusps may differ depending on each case and presenting complaints (Hattab et al 1996).In this report, extraction of involved tooth was advised in all three cases, as the affected teeth were a mesiodens which caused occlusal interference and esthetic problems followed by orthodontic treatment.