Original Article
Effects of three measurement methods on determining the mandibular plane angle
Lu Yun, Liu Shijie, Li Jialun, Kong Runze, Wang Lin
Published 2022-12-20
Cite as Chin J Orthod, 2022, 29(4): 196-200. DOI: 10.3760/cma.j.cn115797-20220511-22404
Abstract
ObjectiveTo investigate how the three mandibular plane definitions, which are MP(G), a line connecting the points Gonion to Gnathion, MP(T), a line tangent to the inferior border of the mandible, and MP(Me), a line tangent to the posterior lower border of the mandible and Mention) can affect the measurements of mandibular plane angle.
MethodsFour hundred new cases in our hospital were collected and measured. The high and low angles cases were screened, and the factors affecting measurement of mandibular plane were analyzed.
Results① Significant differences were detected between MP (T) plane and MP (G) plane, or MP (Me) plane in both MP-SN group and MP-FH group[MP(G)-SN: 37.00°±6.25°, MP(T)-SN: 39.44°±7.08°, MP(Me)-SN: 37.04°±7.12°, MP(G)-SN vs MP(T)-SN: P<0.001, MP(T)-SN vs MP(Me)-SN: P<0.001; MP(G)-FH: 28.21°± 5.58°, MP(T)-FH: 30.65°± 6.35°, MP(Me)-FH: 28.25°±6.40°, MP(G)-FH vs MP(T)-FH: P<0.001, MP(T)-FH vs MP(Me)-FH: P<0.001; no statistical difference was found between MP(G)-SN and MP(Me)-SN, P=0.653, and MP(G)-FH and MP(Me)-FH: P=0.620]; ② The numbers of high angle and low angle cases screened by MP (G), MP (T) and MP (Me) were inconsistent both in MP-SN and MP-FH groups and between two groups; ③ In high angle group, only MP (G)-FH had no correlation with mental morphology (Ratio of chin thickness to Chin height: r=-0.090, P=0.381; Chin angle: r=-0.135, P=0.189); In low angle group, MP(Me)-FH had no correlation with the mental morphology (Chin thickness: r=-0.258, P=0.194; Chin angle: r=-0.229, P=0.109; Ratio of the height of Pogonion height to Chin height: r=-0.318, P=0.100).
ConclusionsOrthodontists should pay attention to the difference of mandibular plane angle formed by MP (T), MP (G) and MP (Me) in diagnosis and analysis. The mandibular plane angle by MP (T) is larger than MP (G) and MP (Me) formed, which have no statistical difference. It is suggested that MP (G)-FH could be used as screen reference for the high angle case, and MP(Me)-FH as the reference for the low angle case.
Key words:
Mandibular plane; Mandibular plane angle; Vertical direction; High angle; Low angle
Contributor Information
Lu Yun
Department of Orthodontics, College of Stomatology, Dalian Medical University, Dalian 116044, China
Liu Shijie
Department of Orthodontics, College of Stomatology, Dalian Medical University, Dalian 116044, China
Li Jialun
West China of Stomatology, Sichuan University, Chengdu 116091, China
Kong Runze
Department of Orthodontics, College of Stomatology, Dalian Medical University, Dalian 116044, China
Wang Lin
Department of Orthodontics, Affiliated Stomatological Hospital of Nanjing Medical University, Jiangsu Province Key Laboratory of Oral Diseases, Nanjing 210029, China
