Cent. Eur. J. Med. • 9(2) • 2014 • 254-263 DOI: 10.2478/s11536-013-0270-6 Central European Journal of Medicine Double teeth: evaluation of 10-years of clinical material Research Article Rafał Koszowski, Jadwiga Waśkowska, Grzegorz Kucharski, Joanna Śmieszek-Wilczewska* Department of Oral Surgery in Bytom, Silesian Medical Academy, Pl. Akademicki 17, 41-902 Bytom, Poland Received 5 June 2013; Accepted 29 October 2013 Abstract: The aim of the study was to evaluate 10-years of clinical material referring to the rare dental abnormality of double teeth. The study material consisted of case records, operation-books and radiographic or photographic documentation on patients treated in the Department of Oral Surgery, Silesian Medical University, Katowice, from the 1st of June 2000 to the 31st of May 2010. The following features were considered important: age and sex, the reason why the patient reported for treatment, general state of health, the time of recognition and type of double teeth, location of double teeth, complaints and disturbances connected with double teeth, types of radiographs, the radiographic and macroscopic appearance of double teeth and treatment method. Diagnoses were as follows: eight conrescent teeth, two fused teeth, two geminated teeth and one invaginated tooth. The anomaly of a deciduous tooth was referred to in one case only. Double teeth were most often seen in the region of maxillary incisors and molars but rarely in the mandible. The region of incisors was affected chiefly in children and the region of molars in adults. Double incisors are usually recognized prior to treatment whereas double molars as late as during their extraction. In many cases, neither intraoral radiographs nor pantomographs help to confirm double teeth or provide sufficient information to plan the treatment. In such a situation, CT or CBCT should be used in addition to imaging diagnostics. Double teeth among incisors are usually accompanied by occlusal disorders. Therefore the therapeutic management is conducted by a team, including orthodontists. Keywords: Dental abnormality • Double teeth • Geminated teeth • Fused teeth • Dens invaginatus © Versita Sp. z o.o 1. Introduction A geminated tooth is usually defined as an abnor- mal formation originating from the division of one tooth Dental abnormalities can be related to distorted crowns, germ [2-6,8,9]. Such division occurs at an early stage roots or entire teeth and changes in their internal struc- of crown development. The resulting abnormal tooth ture. Such abnormalities include, to a large extent, atypi- has either two crowns or one partially separated crown cal formations consisting of two or more conjoined teeth. and one root or such a number of roots as are adequate Due to a variety of underlying pathogenetic mechanisms, for the group of teeth where the original germ belongs. several different terms are used to describe conjoined Such teeth unite at dentin and enamel levels to have teeth. Some authors have introduced the term ”double one crown and one root canal [2-5,8]. Mochizuki et al teeth” to describe a large group of dental abnormalities, [10] and Nahmias et al [11] also describe triple teeth, disregarding their etiology [1-4]. This term applies to but these seem to be geminated teeth considering their such dental anomalies as fusion, gemination, conres- pathogenetic mechanism. Geminated teeth do not lead cence, dens in dente or dens invaginatus [1-6]. Some to a smaller number of teeth in the dental arch unless authors prefer to use the term “syndontia” for fused they cause maleruption or impaction of other teeth or teeth [7] and “schizodontia” for geminated teeth [8]. there are other concomitant defects or disorders. * E-mail: [email protected] 254 J Wilczewska et al. A fused tooth is made as the result of fusion between endocrinological disorders, atavism, thalidomide embry- two separate tooth germs occurring at an early stage opathy, mental diseases [2,6,12,22-24], and crowded of development when the crowns are not yet mineral- adjacent tooth germs or injuries, the latter including ized [1-6,8,9]. The union occurs in the region of dentin chronic mechanical injury e.g. pressure that leads to a and enamel [1-6,9]. The crowns of such teeth are gradual loss of the bone septum between tooth germs excessively large and usually have a groove along the [2,4,12,19,22-24]. It is generally believed that autosomal vestibular surface ending up with a crypt on the incisive recessive inheritance or the low penetration dominant edge. Conrescent teeth replace two teeth in the dental gene plays an important role too [2,4]. Such factors lead arch. They have one common chamber with a crypt cor- to disorders within the dental lamina during the germ responding to a crown groove, two joined chambers and formation process [2,12]. one broad common root canal, or two separate canals Double teeth have often been observed to coexist [1,2,4,6,9]. Conrescence occurs to two normal tooth with other odontogenetic disorders like hyperdontia, hy- germs, one normal tooth germ or one supernumerary podontia, macrodontia or tooth transposition [5,25,26]. It tooth germ [1,4,6]. If a supernumerary tooth becomes has also been observed that 50% of patients with double united with a normal tooth, the total number of teeth in teeth, in deciduous dentition, will develop disorders in the dental arch is not reduced. In such a situation it is permanent dentition including too small or too large a very difficult clinically to differentiate between conres- number of teeth, double teeth, retarded root formation cence and gemination [1,4]. or retarded tooth eruption [1,5,19,25,27]. Double teeth Conrescence is a union, solely in the root cemen- are reported to accompany quite a lot of syndromes tum or, sometimes, in the crowns at enamel level. The like Russel-Silver, ear-finger-facial, Ellis-van Creveld, amount of such unions may vary considerably in extent. cleidocranial, ectodermal dysplasia, Cornelia de Lange, The teeth have separate chambers and root canals [12- Gorlin-Goltz [1,28-30]. In addition, double teeth can also 15,17,19]. Just like in the case of fusion, conrescence coexist with congenital syphilis, syndactyly, squint and may refer to a normal tooth and a supernumerary one nail deformations (19). [12-14,19]. This abnormality occurs at a late stage of de- Many authors share the opinion that double teeth velopment, after crowns and most parts of the roots, or occur usually in deciduous dentition (0.15%-1.2% com- even entire roots, are complete. If the condition occurs pared with 0.1% in permanent dentition) [3,4,12,22,31]. during root formation, it is called true conrescence and However, Brook and Winter [19] report that double teeth is considered a developmental disorder. If the condition are rarely found in deciduous molars. It is also interest- occurs after root formation has completed, it is called ing to note that double teeth are more often observed in acquired conrescence, caused by chronic inflammatory patients coming from The West Indies or Japan and in factors leading to hypercementosis of the joined teeth the Mongolian race than in Caucasians [2,32,33]. [12-14,16]. Conrescent teeth take the place of two teeth Double teeth are observed in maxillas and mandi- in the dental arch. bles alike, but more often in upper incisors and canines Double teeth also include an anomaly called dens in [2,4,6,26]. On the other hand, conrescent teeth are most dente or dens invaginatus. This is a morphological disor- often seen in maxillary molars [12-16,31]. Bilateral oc- der, caused by the invagination of dental papilla before currence of this abnormality is estimated at 0.02% with the germ has mineralized [20,21]. This anomaly usually reference mostly to incisors [2,32,33]. Some authors refers to maxillary lateral incisors or, in rarer cases, to report that double teeth occur equally, both in girls and central incisors, canine teeth and supernumerary teeth. boys [4], while others state that it is more often in boys They are also sometimes found in the region of man- [2,19]. This may be connected with low penetration dibular incisors and premolars [20,21]. The crown of autosomal recessive inheritance [34]. dens invaginatus or dens in dente typically demonstrate abnormal forms. The condition is often recognized acci- dentally during x-ray examination showing impenetrable 2. Aim tissues within the tooth cavity, the saturation thereof being close to enamel [20,21]. Double teeth are rare lesions. The literature describes Most authors believe that the development of double individual cases rather than extensive clinical material. teeth is strongly related to both general and local factors, The aim of this paper is to present an analysis of double including respectively: avitaminosis, hypervitaminosis teeth, as treated in the Department of Oral Surgery, at A, systemic diseases, the RH incompatibility of parents, the Silesian Medical University, Katowice. 255 Double teeth 3. Material and method Adult patients (cases no.4,7,8,9,and 10) demon- strated double teeth among molars, namely four (cases The study material consisted of medical documents no.4,8,9,and 10) in the maxilla and two (cases no.7 (case records, operation-books, x-ray and photographic and 13) in the mandible. Double teeth were discovered documents) referring to patients treated in the Depart- in four women and one man. Maxillary second and ment of Oral Surgery from the 1st of June 2000 to the third molars were conjoined in four patients (cases 31st of May 2010. Patients only with double teeth were no.4,8,9,and 10), and mandibular third molar was joined selected for the study, and the following features were to supernumerary tooth 39 in two (cases no.7 and 13).