Journal of Prevention and Treatment for Stomatological Diseases ›› 2019, Vol. 27 ›› Issue (8): 522-526.doi: 10.12016/j.issn.2096-1456.2019.08.009

• Cinical Study • Previous Articles     Next Articles

Anatomical morphology of the root and root canal system of the second permanent molar in the Uygur people

LIU Fang1,GU Yongchun2(),GUO Hong3,TANG Ying2,LIU Chao2,SHEN Yifen2   

  1. 1. Department of Stomatology, The First People′s Hospital of Urumqi, Urumqi City 830000, China;
    2. Central Lab, The Ninth People′s Hospital of Suzhou, Suzhou 215200, China;
    3. Department of Periodontics, The Stomatological Hospital of Urumqi, Urumqi City 830000, China
  • Received:2018-02-23 Revised:2018-11-15 Online:2019-08-20 Published:2019-08-16
  • Contact: Yongchun GU


Objective To study the anatomical characteristics of the root and root canal system of the mandibular second permanent molar in the Uygur people and provide a reference for clinical practice.Methods A total of 125 mandibular second permanent molars were extracted from Uygur patients in hospitals in the Xinjiang Uygur Autonomous Region. Three-dimensional reconstruction was performed after micro-CT scanning. The number of root canals, the root canal type (Weine classification and Fan′s C-shaped canal classification) and the occurrence of lateral accessory canals were observed.Results A sex difference was not detected in the root number or root form (χ 2 = 1.277, P = 0.259). The incidence of 2-rooted molars was 70.4% (n = 88); type 2-1 canals were most common in the mesial root, with an incidence of 29.5%, followed by type 1-1 and 2-2 canals (each with an incidence of 26.1%), and the distal root mostly had a type 1-1 canal (96.6%). The incidence of single-rooted molars was 28.8%, and the frequency of C-shaped (n = 28) and non-C-shaped (n = 8) single-rooted molars was 22.4% and 6.4%, respectively. A three-rooted molar was detected in one case. The incidence of accessory canals was 65.2%.Conclusion Uygur mandibular second molars are mainly composed of two roots, and the incidence of a single root and root canal fusion is low (including C-shaped canals). Two-rooted molars frequently have two mesial canals and one distal canal.

Key words: Uygur people, permanent mandibular second molar, root canal system, C-shaped canal, micro-CT

CLC Number: 

  • R781.33

Figure 1

Fan′s classification of C-shaped canals"

Figure 2

Three-dimensional reconstruction of the root canal system of two-rooted mandibular second molars"

Table 1

Root canal morphology of 88 permanent mandibular second molars n = 88(%)"

牙根 1-1型 1-2型 2-1型 2-2型 1-2-1型 2-1-2型 其他型
MR 23(26.1) 4(4.5) 26(29.5) 23(26.1) 5(5.7) 2(2.3) 5*(5.7)
DR 85(96.6) 1(1.1) 0(0) 0(0) 2(2.3) 0(0) 0(0)

Table 2

Root canal forms of C-shaped and single-rooted mandibular second molars"

根管类型 n Weine根管分型 范兵C形根管分型
1-1 1-2 2-1 2-2 n C1 C3 C2+C3 C1+C3 C1+C2+C3 n
非C形单根 8 1 1 0 2 4 3 0 1 0 0 4
C形单根* 28 0 0 0 0 0 2 8 1 3 14 28

Figure 3

Three-dimensional reconstruction of C-shaped mandibular second molars"

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