Jorge N R Martins1, Christian Nole2, Hani F Ounsi3, Peter Parashos4, Gianluca Plotino5, Magnús F Ragnarsson6, Ruben Rosas Aguilar7, Fábio Santiago8, Hussein C Seedat9, Walter Vargas10, Murilo von Zuben11, Yuerong Zhang12, Hussam Alfawaz13, Moataz-Bellah A M Alkhawas14, Zaher Altaki15, Luiza Berti16, Carlos Boveda17, Imran Cassim18, Antonis Chaniotis19, Daniel Flynn20, Jose Antonio Gonzalez21, Jojo Kottoor22, Adam Monroe23, Emmanuel J N L Silva24, Marco Aurélio Versiani25. 1. Department of Endodontics, Faculdade de Medicina Dentária, Universidade de Lisboa, Lisbon, Portugal; Instituto de Implantologia, Lisbon, Portugal. Electronic address: jnr_martins@yahoo.com.br. 2. Private Practice, Lima, Peru. 3. Department of Restorative Dentistry and Endodontics, Lebanese University, Beirut, Lebanon; Department of Endodontics and Restorative Dentistry, Siena University, Siena, Italy. 4. Melbourne Dental School, University of Melbourne, Melbourne, Australia. 5. Private Practice, Rome, Italy. 6. Private Practice, Hafnarfjördur, Iceland. 7. Department of Endodontics, Escuela Nacional de Estudios Superiores Universidad Nacional Autónoma de México (UNAM), León, México. 8. Private Practice, Paris, France. 9. Private Practice, Durban, South Africa. 10. Instituto de Estudios Avanzados en Odontología Dr. Yury Kuttler, Mexico City, Mexico. 11. Private Practice, Brussels, Belgium. 12. Department of Conservative Dentistry and Endodontics, School of Stomatology, Nanjing Medical University, Nanjing, China. 13. King Saud University, College of Dentistry, Riyadh, Saudi Arabia. 14. Department of Endodontics, Al-Azhar University Faculty of Dental Medicine, Cairo, Egypt. 15. Department of Endodontics, Damascus University, Damascus, Syria. 16. Department of Radiology, Faculdade de Odontologia São Leopoldo Mandic, Campinas, Brazil. 17. Department of Endodontics, Faculty of Dentistry, Universidad Central de Venezuela, Caracas, Venezuela. 18. Private Practice, Tauranga, New Zealand. 19. Private Practice, Athens, Greece. 20. Private Practice, London, England. 21. Departamento de Endodoncia y Conservadora, Facultad de Odontología, Universitat Internacional de Catalunya, Barcelona, Spain. 22. Department of Conservative Dentistry and Endodontics, Royal Dental College, Kerala, India. 23. Private Practice, San Diego, CA. 24. Department of Endodontics, School of Dentistry, Grande Rio University, Rio de Janeiro, Rio de Janeiro, Brazil; Department of Endodontics, Fluminense Federal University, Niteroi, Rio de Janeiro, Brazil. 25. Dental Specialty Center, Brazilian Military Police, Minas Gerais, Brazil.
Abstract
INTRODUCTION: This study assessed the prevalence of radix entomolaris and 2 canals at the distal aspect of mandibular first molars among different geographic regions by means of cone-beam computed tomographic imaging. METHODS: Precalibrated observers from 23 worldwide geographic locations followed a standardized screening protocol to assess 5750 cone-beam computed tomographic images of mandibular first molars (250 per region), gathering demographic data and recording the presence of radix entomolaris and a second canal at the distal aspect of teeth. Intra- and interrater reliability tests were conducted and comparisons among groups were performed using proportions and odds ratio forest plots. The significance level was set at 5%. RESULTS: The results of intra- and interrater tests were above 0.79. The prevalence of radix entomolaris varied from 0.9% in Venezuela (95% confidence interval [CI], 0%-1.9%) to 22.4% in China (95% CI, 17.2%-27.6%). Regarding the proportion of a second distal canal, it ranged from 16.4% in Venezuela (95% CI, 11.8%-21.0%) to 60.0% in Egypt (95% CI, 53.9%-66.1%). The East Asia subgroup was associated with a significantly higher prevalence of an extra distolingual root, whereas the American subgroup, the American native ethnic group, and elderly patients were linked to significantly lower percentages of a second canal at the distal aspect of teeth. No significant differences were noted between male or female patients. CONCLUSIONS: The overall worldwide prevalence rates of radix entomolaris and a second canal at the distal aspect of the mandibular first molar were 5.6% and 36.9%, respectively. The East Asia geographic region and Asian ethnic group had a higher prevalence of a second distal root.
INTRODUCTION: This study assessed the prevalence of radix entomolaris and 2 canals at the distal aspect of mandibular first molars among different geographic regions by means of cone-beam computed tomographic imaging. METHODS: Precalibrated observers from 23 worldwide geographic locations followed a standardized screening protocol to assess 5750 cone-beam computed tomographic images of mandibular first molars (250 per region), gathering demographic data and recording the presence of radix entomolaris and a second canal at the distal aspect of teeth. Intra- and interrater reliability tests were conducted and comparisons among groups were performed using proportions and odds ratio forest plots. The significance level was set at 5%. RESULTS: The results of intra- and interrater tests were above 0.79. The prevalence of radix entomolaris varied from 0.9% in Venezuela (95% confidence interval [CI], 0%-1.9%) to 22.4% in China (95% CI, 17.2%-27.6%). Regarding the proportion of a second distal canal, it ranged from 16.4% in Venezuela (95% CI, 11.8%-21.0%) to 60.0% in Egypt (95% CI, 53.9%-66.1%). The East Asia subgroup was associated with a significantly higher prevalence of an extra distolingual root, whereas the American subgroup, the American native ethnic group, and elderly patients were linked to significantly lower percentages of a second canal at the distal aspect of teeth. No significant differences were noted between male or female patients. CONCLUSIONS: The overall worldwide prevalence rates of radix entomolaris and a second canal at the distal aspect of the mandibular first molar were 5.6% and 36.9%, respectively. The East Asia geographic region and Asian ethnic group had a higher prevalence of a second distal root.