Fourth molar: A retrospective study and literature review of a rare clinical entity

Babatunde O. Bamgbose, Shunsuke Okada, Miki Hisatomi, Yoshinobu Yanagi, Yohei Takeshita, Zahrau Saleh Abdu, Edugie J. Ekuase, Jun ichi Asaumi

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Purpose: The prevalence of supernumerary teeth has been reported to be between 0.1% and 3.8%. The aim of this study was to determine the prevalence, clinical significance, and associated pathologies of fourth molars based on a retrospective study and a literature review. Materials and Methods: A 5-year retrospective prevalence study was conducted at the Department of Oral Diagnosis and Dentomaxillofacial Radiology of Okayama University Hospital, Okayama, Japan. The study involved extracting data from the digital records of patients from January 1, 2013 through December 31, 2017. The sampling frame included all patients who had panoramic radiographs, cone-beam computed tomography (CT), and multislice CT images during the period under review. Results: A total of 26,721 cases were reviewed and 87 fourth molars were identified. The prevalence of fourth molars in the 5-year study at Okayama was calculated as 0.32%. The mean age of patients with a fourth molar was 30.43 years, and the male-to-female ratio was 1:0.98. The vast majority of cases were in the maxilla (92%) and had normal shapes (89.7%); furthermore, 82.8% of cases were unerupted. Conclusion: The prevalence of fourth molars in the study population was found to be 0.32%, and fourth molars occurred with approximately equal frequency in males and females. Fourth molars were more common in the maxilla and were predominantly unerupted and small.

Original languageEnglish
Pages (from-to)27-34
Number of pages8
JournalImaging Science in Dentistry
Issue number1
Publication statusPublished - Mar 1 2019


  • Odontogenic cyst
  • Odontoma
  • Supernumerary
  • Tooth

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Dentistry(all)
  • Radiology Nuclear Medicine and imaging


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