Stomatology ›› 2023, Vol. 43 ›› Issue (1): 57-61.doi: 10.13591/j.cnki.kqyx.2023.01.010

• Clinical Research • Previous Articles     Next Articles

Relationship between congenital absence of third molars and craniomaxillofacial structure

WU Lina,XIONG Xin,WU Yange,ZHANG Qinlanhui,WANG Jun()   

  1. State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Orthodontics, West China School of Stomatology, Sichuan University, Chengdu 610041, China
  • Revised:2022-10-10 Online:2023-01-28 Published:2023-01-11
  • Contact: WANG Jun E-mail:wangjunv@sdu.edu.cn

Abstract: Objective To analyze the correlation between third molar agenesis and craniofacial morphology by studying the location and number of congenital missing third molars and results of craniofacial cephalometric measurement. Methods A total of 123 patients were included, including 64 patients in the control group without congenital third molar absence and 59 patients in the absence group with at least one third molar absent. Cephalometric measurements included FMA, IMPA, AR-Go, GoGn-Sn, Co-A, Co-Gn, ANS-Me, Go-Me, SN-MP, Ar-Go-Me, SNA, SNB, ANB, Y-axis angle, Y-axis length, Ar-Go, Go-Me, MP-OP, FH-PP, FH-OP, a total of 18 bone tissue indicators, U1-SN, U1-L1, U1-NA, L1-NB, U1-APo and L1-APo, a total of 6 dental indicators, and UL-EP, LL-EP and nasolabial angle, a total of 3 soft tissue indicators. The correlation between congenital agenesis of third molars and craniofacial morphology was analyzed. Results The most common missing location of the third molar occured in the upper jaw and the most common number of missing teeth was one. In control group, Ar-Go-Me and SN-MP were larger (P<0.05), U1-SN, U1-NA, L1-NB, UL-EP and LL-EP were larger (P<0.05), and U1-L1 was smaller (P<0.01). There were no significant differences in Ar-Go and Go-Me between the two groups(P>0.05). Conclusion Patients with four third molars are more likely to have backward and downward rotation of the mandible and are more likely to develop into a convex facial type than patients with missing third molars, which has a higher correlation with hyperdivergent growth pattern and convex facial type.

Key words: third molar, craniomaxillofacial structure, cephalometric measurement

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