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Multiple supernumerary teeth are rare in non-syndromic patients1 and are mainly impacted.2 A 26-year-old man presented with four supernumerary teeth around the left maxillary second molar. He was referred to our clinic to remove the left maxillary third molar and four supernumerary teeth because of the bite in the buccal mucosa. He had no significant medical history, except for hay fever, or congenital deformities. Two maxillary central impacted supernumerary teeth were removed at 11 years of age. He had no family history of supernumerary teeth, congenital deformity, or colorectal tumours. However, his younger brother had a congenitally missing tooth. In the intraoral examination, four supernumerary teeth around the left maxillary were noted: one supernumerary tooth on the palate side and three supernumerary teeth on the buccal side (figure 1A). The panoramic radiograph showed no residual deciduous teeth and congenital loss of the permanent teeth. Cone-beam CT showed four supernumerary teeth around the left maxillary second molar, and these teeth were single-rooted and thinly curved (figure 1B). All supernumerary teeth and the left maxillary third molar were removed under local anaesthesia. All supernumerary teeth showed microdontia with single roots. Each crown form was different. Conical crowns, incisor-like crowns and crowns with 2 and 4 cusps were noted. The length and width of the supernumerary teeth were 9–13 and 3–5 mm, respectively (figure 1C).
The prevalence of supernumerary teeth is approximately 1% and that of the maxillary central impacted supernumerary tooth is approximately 50%, with the occurrence in one or two teeth.3 Multiple supernumerary teeth with four or more teeth occur in cleidocranial dysplasia and Gardner syndrome.4 5 Multiple supernumerary teeth are rare in patients without the syndrome.1 Reportedly, 25% of supernumerary teeth erupt, while 75% are impacted.6 In this case, four multiple supernumerary teeth erupted, and these were around one tooth. Although the mechanism of occurrence of the supernumerary teeth is unclear, the phylogenetic theory, tooth germ dichotomy theory, and dental lamina hyperactivity theory have been advocated.7 8 In this case, the dental lamina hyperactivity theory was considered because there was no fusion with the second or third molars, and the developmental time was independent.
Multiple supernumerary teeth with four or more teeth occur in cleidocranial dysplasia and Gardner syndrome.
Multiple supernumerary teeth are rare in non-syndromic patients and are mainly impacted.
The authors thank Prof. Tomohiro Ando for his valuable comments.
Contributors All authors contributed to the design and implementation of the research, to the analysis of the results and to the writing of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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