Incidence of three roots and/or four root canals in the permanent mandibular first molars in a Korean sub-population.
OBJECTIVE
The purpose of this study was to evaluate the prevalence of three-rooted permanent mandibular first molars (PMFMs) with four canals and their morphological characteristics among a Korean population from using cone-beam computed tomography scans (CBCTs).


METHODS
Among the 705 CBCTs screened, 472 patient cases possessing at least one PMFM were identified. A total of 780 PMFMs were evaluated in axial section series to determine the number of roots and canals. The incidences of three-rooted PMFMs were compared with regard to gender and location. For distal root(s) with two canals, inter-orifice distances (IOD) between distobuccal and distolingual canals were measured at pulpal floor and furcation levels. The difference of IOD between males and females was also analyzed using chi-square tests.


RESULTS
Among the 472 CBCTs of 225 females and 247 males, 84 females and 107 males were found to have at least one three-rooted PMFM. Among the 780 PMFMs, 191 PMFMs (24.5%, 89 of 397 left and 102 of 383 right) were found to have three roots. The prevalence of distal root(s) with two canals was 34.2% (267 of 780). From the molars with two distal canals, the mean IOD between distobuccal and distolingual canals at the pulpal floor level was 3.1 mm in males and 2.9 mm in females (p = 0.0428).


CONCLUSIONS
The occurrence of three-rooted PMFMs among a Korean population was 24.5% and was higher than other countries and ethnicities. Understanding the prevalence of PMFMs with a distolingual root and/or canal in a Korean population and the IOD between distobuccal and distolingual canals may be useful for successful endodontic treatments.


CONCLUSIONS
Acknowledgment of potential incidence of three-rooted permanent mandibular first molars with four canals and the distance between two distal canals may increase the success rate of root canal treatment by reducing the missing canal untreated.
Department of Conservative Dentistry, School of Dentistry, Pusan National University, Beomeo-Ri, Mulgeum, Yangsan, Gyeongnam, 626-810, South Korea.
Ju-Kyong
JK
Jang
Ove A
OA
Peters
Woocheol
W
Lee
Sung-Ae
SA
Son
Jeong-Kil
JK
Park
Hyeon-Cheol
HC
Kim
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D003782:Dental Pulp / Q000000981:diagnostic imaging; D003786:Dental Pulp Cavity / Q000002:abnormalities / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging; D008875:Middle Aged; D008963:Molar / Q000000981:diagnostic imaging*; D009811:Odontometry / Q000379:methods; D056910:Republic of Korea; D012189:Retrospective Studies; D012737:Sex Factors; D014092:Tooth Root / Q000002:abnormalities / Q000000981:diagnostic imaging*; D055815:Young Adult