PRACTICE BRITISH DENTAL JOURNAL VOLUME 197 NO. 6 SEPTEMBER 25 2004 307 Five mandibular incisors: an autosomal recessive trait? A. Cassia 1 , S. El-Toum 2 , A. Feki 3 and A. Megarbane 4 A fifth mandibular incisor is a eumorphic supernumerary tooth and has rarely been described in the medical literature. We report here a large Lebanese consanguineous family where four individuals displayed five incisors in the anterior mandible. Such familial observation has not been previously described. The possibility of an autosomal recessive inheritance for this nonsyndromic trait is discussed. 1 Postgraduate Director, Department of Oral Diagnostic Sciences, Lebanese University School of Dentistry, Beirut, Lebanon; 2 *Dental Surgeon, Department of Oral Diagnostic Sciences, Lebanese University School of Dentistry, Beirut Lebanon; 3 Professor, Department of Oral Medicine and Oral Surgery, University Hospital of Strasbourg, France; 4 Director, Medical Genetic Unit, Saint-Joseph University, Beirut, Lebanon Correspondence to: Sami El-Toum, First floor, Sader Building, Slaf Dekouaneh, PO Box: 55 - 053, Beirut, Lebanon E-mail: seltoum@idm.net.lb Refereed Paper Received 20.05.02; Accepted 23.10.03 doi:10.1038/sj.bdj.4811648 © British Dental Journal 2004; 197: 307–309 INTRODUCTION Supernumerary teeth (or hyperdontia) result in an increased number of teeth within the dental arches. 1–5 It can be clas- sified as either eumorphic or dysmor- phic. 4,5 A eumorphic supernumerary tooth has the same morphology as a normal tooth while dysmorphic teeth are small and conical or tuberculate. 4,5 Incidence of a eumorphic supernumerary incisor in the mandible is very low. 2,4,6,7,8 Very few cases of five mandibular incisors have been described in the literature. 3,6,9,10 We report here a lebanese family with four individuals displaying five mandibu- lar incisors. CASE REPORTS The family originates from the Bekaa valley in Lebanon. All patients, their par- ents, sisters and brothers were clinically and radiologically investigated. First patient (VIII.1, Fig. 1) A 25-year-old male with a non-contribu- tory medical history. Clinical examination and periapical radiograph revealed five well individu- alised mandibular incisors with an over- lap between a lateral incisor and the cusp on the right side. All incisors had normal roots, pulp chambers and canal mor- phologies and they were well aligned (Fig. 2a,b). Tooth measurements on plaster casts, with a calliper square, showed that the first right incisor was not much bigger than the neighbouring ones but was considerably bigger than the central incisor (Table 1). The patient's parents were partially edentulous with four mandibular incisors. ● A large consanguineous family with four individuals displaying five incisors in the anterior mandible is described. ● This family condition led us to propose a hypothesis of an autosomal recessive inheritance for this trait. ● In future such a family might help localise a gene responsible for this trait. ● This gene’s localisation helps us to understand more of the aetiology of supernumerary teeth and to investigate genetic counselling with the establishment of a genetic treatment. IN BRIEF Fig. 2a First patient, buccal view Fig. 2b First patient, horizontal periapical radiograph Table 1 Measurements of the anterior teeth in the mandible of first patient Tooth from right to left First Second Third Fourth Fifth Mesiodistal crown width (mm) 6.8 6.5 6.3 6.3 6.6 Labiolingual crown width (mm) 7.3 7.35 7.3 7.3 7.3 Crown length (mm) 9.4 9.15 9.4 8.8 8.6