ORIGINAL ARTICLE Oral Bioscience Prevalence and characteristics of non-syndromic distomolars: a retrospective study Elif Kaya, Kahraman G€ ung € or, O guzhan Demirel & € Ozge € Oz € ut € urk Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Gazi University, Ankara, Turkey Keywords distomolar, fourth molar, non-syndromic, panoramic radiograph, supernumerary teeth. Correspondence Dr Elif Kaya, Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Gazi University, Bis ßkek Cad 84, Sokak Emek, Ankara 06510, Turkey. Tel: +90-312-2034158 Email: dtelifkaya@gmail.com Received 27 September 2013; accepted 20 March 2014. doi: 10.1111/jicd.12108 Abstract Aim: Distomolars are defined as the supernumerary teeth that erupt distal to the third molar. The aim of the present study was to evaluate the prevalence of distomolars in permanent dentition in a non-syndromic Turkish subpopulation. Methods: A total of 10 111 panoramic radiographs of patients aged 18 years and over, who had no systemic diseases and syndromes, and who had not undergone any extractions in the third molar area, were examined to determine the presence, location, shape, and laterality of distomolars. The patients’ age and sex were noted. Results: The results showed that distomolars were observed in 0.26% of the investigated population. Distomolars were seen in 0.29% of male patients and in 0.23% of female patients. In total, 30 distomolars were observed in 26 patients. Maxillary distomolars were more frequently encountered than man- dibular teeth. Bilateral distomolars were found in three male patients. Of the 30 distomolars, 25 were impacted and five were erupted. Conclusions: Although the frequency of distomolars is low, early diagnosis and treatment are important to minimize or prevent complications, such as delayed eruption, tooth displacement, crowding, root resorption of the adjacent tooth, and cystic formations. Introduction Supernumerary teeth are defined as an excessive number of teeth than normal in the dental arch. 1 The etiology of hyperdontia is unknown. Nevertheless, various theories have been proposed. These theories include the phylogenetic theory (i.e. teeth that exist in primitive time and lost in the current time period), hyperactivity of the dental lamina, environmental and genetic factors, and the dichotomy theory (i.e. complete separation of the tooth bud). 2–5 Supernumerary teeth might be seen in the upper or lower jaw, and can be single or multiple, and unilateral or bilateral. Single and multiple supernumerary teeth are seen in various syndromes and developmental disorders, such as Cleidocranial dysostosis, Gardner’s syndrome, Ehlers– Danlos syndrome, and Fabry–Anderson syndrome. 6–8 Hyperdontia is more common in permanent dentition than primary dentition. 9 The incidence of hyperdontia in permanent dentition is reported to be 0.1–2.1%, and 0.3– 0.8% in primary dentition. 9,10 Supernumerary teeth might be normal shape, (i.e. sup- plemental) or abnormal (i.e. rudimentary), such as coni- cal, tuberculate, or a mass of dental tissue. 11 Supernumeraries can be classified according to their locations. The supernumerary teeth between the maxillary central incisors are mesiodens, those in the molar area are paramolar, and those that erupt distal to the third molar are distomolars. 9 The aim of the present study was to evaluate the preva- lence of distomolars in permanent dentition in a non- syndromic Turkish subpopulation. Materials and methods We planned a retrospective observational study that included 10 111 panoramic radiographs that were taken on patients who applied to our Oral and Maxillofacial 282 ª 2014 Wiley Publishing Asia Pty Ltd Journal of Investigative and Clinical Dentistry (2015), 6, 282–286