University of Oulu

Ventä, I., Huumonen, S. & Suominen, A.L. How many third molars remain unnoticed in a population survey without panoramic radiographs?. Clin Oral Invest (2019).

How many third molars remain unnoticed in a population survey without panoramic radiographs?

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Author: Ventä, Irja1; Huumonen, Sisko2,3,4; Suominen, Anna Liisa2,5,6
Organizations: 1Department of Oral and Maxillofacial Diseases, Faculty of Medicine, University of Helsinki, P.O. Box 41, FI-00014, Helsinki, Finland
2Institute of Dentistry, University of Eastern Finland, Kuopio, Finland
3Diagnostic Imaging Center, Kuopio University Hospital, Kuopio, Finland
4Research Unit of Oral Health Sciences, University of Oulu, Oulu, Finland
5Department of Oral and Maxillofacial Diseases, Kuopio University Hospital, Kuopio, Finland
6Public Health Evaluation and Projection Unit, National Institute for Health and Welfare, Helsinki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.3 MB)
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Language: English
Published: Springer Nature, 2020
Publish Date: 2020-02-25


Objective: The aim of the study was to compare the findings of clinical examination and panoramic radiograph regarding the occurrence of third molars in a population survey to find out how many third molars remain clinically unnoticed.

Materials and methods: A two-staged stratified cluster-sampling method was used to select 8028 participants representing the adult population aged 30 years and older. Clinical oral examinations and panoramic radiographs were carried out for 5989 subjects (46% men, 54% women; mean age 52.5, SD 14.6; range 30–97 years). Clinical recordings of the presence of third molars were compared with the radiographs. Statistics included chi-squared, Fisher’s, Wilcoxon’s, and Kruskal-Wallis tests.

Results: In the 5989 subjects, 3742 third molars were recorded in the clinical examination, and 5912 were observed in the panoramic images, a difference of 2170 teeth. Furthermore, related to 3668 (61%) of the third molars, both clinical and radiographic recordings were attributed to the same third molar, while 2244 third molars were observed only in the panoramic image, and 74 only in the clinical examination. In every age group, the mean number of third molars per subject was larger radiographically compared with the clinical recordings (means for all 0.99 vs. 0.62; P < 0.001).

Conclusion: Numbers of third molars, recorded in clinical examination alone, are underreported by approximately one-third compared with radiographic findings.

Clinical relevance: The numbers of third molars in a population survey without a panoramic radiograph do not reflect the total number of third molars in a population.

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Series: Clinical oral investigations
ISSN: 1432-6981
ISSN-E: 1436-3771
ISSN-L: 1432-6981
Volume: In press
DOI: 10.1007/s00784-019-03134-1
Type of Publication: A1 Journal article – refereed
Field of Science: 313 Dentistry
Funding: Open access funding provided by University of Helsinki including Helsinki University Central Hospital.
Copyright information: © 2019 The Authors. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.