Three-dimensional morphologic analysis of isthmuses in the mesial roots of mandibular molars.
BACKGROUND
The purpose of this study was to investigate the three-dimensional (3-D) morphology of isthmuses in the mesial roots of mandibular molars.


METHODS
One hundred twenty-six extracted mandibular molars including 70 first molars (MFMs) and 56 second molars (MSMs) from a Chinese population were scanned by micro-computed tomography, and the apical 5 mm of the root canals with or without isthmuses was reconstructed with 3D-Doctor software. Each reconstructed isthmus model was assigned to 1 of the following 4 categories: sheet connection, separate, mix, and cannular connection. The length of the isthmus (L(i)) and the distance from the bottom of the isthmus to apex (D(ba)) were measured and analyzed.


RESULTS
The incidence of an isthmus in the apical 5 mm of the mesial roots was 85%. MFMs had more isthmuses with separate type and mixed type, whereas MSMs had more isthmuses with sheet connections. The L(i) and D(ba) in mandibular molars were 2.331 mm and 1.850 mm, respectively.


CONCLUSIONS
MFMs present different anatomical features of isthmuses in the apical part of the mesial roots than MSMs.
State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) & Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China. b.fan@163.com
Bing
B
Fan
Yihuai
Y
Pan
Yali
Y
Gao
Fang
F
Fang
Qingsong
Q
Wu
James L
JL
Gutmann
D019412:Anatomy, Cross-Sectional; D002681:China; D003786:Dental Pulp Cavity / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008334:Mandible; D008963:Molar / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D012984:Software; D019227:Tooth Apex / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014092:Tooth Root / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography / Q000379:methods*