1. The Prevalence of Three-rooted Permanent Mandibular Molars
17th International Symposium on Dental Morphology (ISDM) &
2nd congress of International Association for Paleodontology (IAPO)
The Prevalence of Three-rooted Permanent Mandibular Molars
in the Slovenian Population
Lucija Strmšek Iztok Štamfelj1,2
1Department of Dental Diseases and Dental Morphology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
2Department of Operative Dentistry and Endodontics, University Medical Centre Ljubljana, Ljubljana, Slovenia
1 INTRODUCTION
Three-rooted permanent mandibular molars (3RM) have great clinical significance and interesting geographic distribution. Nevertheless, studies on the prevalence of 3RM in European populations are sparse and mostly limited to the permanent mandibular first molar (Table 1).
Table 1: Survey of Available Studies on the Prevalence of Three-rooted Permanent Mandibular Molars in European Populations
Author
Year
Population
Material
Permanent mandibular molars
First (%)
Second (%)
Third (%)
Taylor
1899
England
Extracted teeth
3.4 -
Fabian
1928
Germany
1.6
Visser
1948
Netherlands
1.1
0.14
0.85
Hjelmman
1929
Finland
0.9
de Souza-Freitas et al.
1971
European descent
3.2
Curzon
1973
Schäfer et al.
2009
Radiographs
0.7
Colak
2012
Turkey
1.0
2 AIM
The aim of this retrospective study was to assess the prevalence of the third root in all three permanent mandibular molars among a Slovenian dental school patient population.
3 MATERIALS AND METHODS
The dental records of patients visiting students and interns in the Centre for Operative Dentistry and Endodontics during the last 10 years were screened patients (609 males and 709 females) possessing intraoral (periapical or bite-wing) radiograph of at least one permanent mandibular molar were selected. These radiographs were evaluated independently by two observers under optimal conditions. Disagreements were discussed until a consensus was reached. The prevalence of the third root in different types of mandibular molars was determined. The correlations between left- and right-side occurrences and between males and females were analyzed by using the chi-square test.
4 RESULTS
The overall prevalence of 3RM was 0.95% (1.32% for the first molar, 0.25% for the second molar, and 1.77% for the third molar) (Table 2). There was neither a significant difference according to sex, nor the side of occurrence (left vs. right side) in any type of mandibular molars (p > 0.05) (Table 2).
Table 2: Number and Percentage of Three-rooted Permanent Mandibular Molars in Slovene Patients
Mandibular molars
Right
Left
Male
Female
All N n %
First
679 10
1.47
682 8
1.17
660 11
1.67
701 7
1.00
1361 18
1.32
Second
791 3
0.38
782 1
0.13
753 2
0.27
820
0.24
1573 4
0.25
Third
372 5
1.34
362
2.20
334
0.90
400
2.50
734 13
1.77
1842
0.98
1826 17
0.93
1747 16
0.92
1921 19
0.99
3668 35
0.95
Legend: N - number of examined molars, n - number of three-rooted molars, % - percentage of three-rooted molars
5 CONCLUSIONS
Relatively low prevalence of 3RM in the Slovenian population is in agreement with available data for Europeans.
Our results indicate that the third root occasionally develops in all types of permanent mandibular molars; however, this occurs least frequently in the second molar.
The clinician should allways consider the possibility of 3RM when treating European patients.