Retained Primary Molars and Related Reasons in Umm Al-Qura University, Makkah: A Retrospective Study

Ghazal Iraqi1, *, Narmin Helal2, Abla Arafa3, Faris Helal1
1 Faculty of Dentistry, Umm Al-Qura University, Makkah ,24211, Western Región, Saudí Arabia
2 Department of Pediatric Dentistry, King Abdulaziz University, Jeddah ,21577, Western Región, Saudí Arabia
3 Department of Pediatric Dentistry and Dental Public Health, Faculty of Oral and Dental Medicine, Misr International University, Cairo, Egypt at sabbatical leave to Faculty of Dentistry, Umm Al-Qura University, Makkah, Saudi Arabia

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© 2019 Iraqi et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Faculty of Dentistry, Umm Al-Qura University, Makkah, 24211, Western Región, Saudí Arabia;
Tel: +19179309113; Email:



Retention of primary molars beyond the expected time of exfoliation is uncommon; this condition is known as persistence. A retained primary tooth, with the crown in good condition, roots, and supporting alveolar bone can serve adults for many years.


To determine the prevalence of retained primary molars and investigate the reasons for their persistence in Umm Al-Qura University.


Overall, 500 extra-oral panoramic radiographs were assessed to investigate whether primary molars persisted beyond the expected exfoliation period. Dental records were also reviewed to investigate the possible reasons for persistence. The collected data were tabulated and statistically analyzed, with P < .05 considered significant.


Seventy-six retained primary molars were identified (39 in females and 37 in males) in 500 panoramic radiographs (from 260 females and 240 males). Agenesis of the permanent successor tooth was the most frequently encountered reason for the retention of primary molars (19%). The second most frequent reason was ectopic deviation of the path of eruption of the successor (11%). The third most common reason was impaction of the successor (10%).


The incidence of retained primary molars in the investigated population was 15.2%. The most common reason for the persistence of primary molars was agenesis of the permanent successor, followed by ectopic eruption and impaction of the successor teeth. These data highlight the need for education and awareness of dentists and patients to preserve the primary tooth when there is no permanent successor present and support an appropriate treatment plan for each case.

Keywords: Ectopic eruption, Impaction, Persistence, Primary molar, Successor tooth, Panoramic radiographs.