Shinkai Rosemary S, Lazzari Fabio L, Canabarro Simone A, Gomes Márcia, Grossi Márcio L, Hirakata Luciana M, Mota Eduardo G
Department of Prosthodontics, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
Head Face Med. 2007 Apr 2;3:18. doi: 10.1186/1746-160X-3-18.
Vertical facial pattern may be related to the direction of pull of the masticatory muscles, yet its effect on occlusal force and elastic deformation of the mandible still is unclear. This study tested whether the variation in vertical facial pattern is related to the variation in maximum occlusal force (MOF) and medial mandibular flexure (MMF) in 51 fully-dentate adults.
Data from cephalometric analysis according to the method of Ricketts were used to divide the subjects into three groups: Dolichofacial (n = 6), Mesofacial (n = 10) and Brachyfacial (n = 35). Bilateral MOF was measured using a cross-arch force transducer placed in the first molar region. For MMF, impressions of the mandibular occlusal surface were made in rest (R) and in maximum opening (O) positions. The impressions were scanned, and reference points were selected on the occlusal surface of the contralateral first molars. MMF was calculated by subtracting the intermolar distance in O from the intermolar distance in R. Data were analysed by ANCOVA (fixed factors: facial pattern, sex; covariate: body mass index (BMI); alpha = 0.05).
No significant difference of MOF or MMF was found among the three facial patterns (P = 0.62 and P = 0.72, respectively). BMI was not a significant covariate for MOF or MMF (P > 0.05). Sex was a significant factor only for MOF (P = 0.007); males had higher MOF values than females.
These results suggest that MOF and MMF did not vary as a function of vertical facial pattern in this Brazilian sample.
垂直面部形态可能与咀嚼肌的牵拉方向有关，但其对咬合力和下颌骨弹性变形的影响仍不明确。本研究测试了51名全口牙齿健全的成年人垂直面部形态的变化是否与最大咬合力（MOF）和下颌骨内侧弯曲（MMF）的变化有关。
根据里氏方法进行头影测量分析的数据，将受试者分为三组：长面型（n = 6）、中面型（n = 10）和短面型（n = 35）。使用置于第一磨牙区域的跨牙弓力传感器测量双侧咬合力。对于MMF，在下颌咬合面处于休息位（R）和最大开口位（O）时制取印模。对印模进行扫描，并在对侧第一磨牙的咬合面上选择参考点。MMF通过用休息位时的磨牙间距离减去最大开口位时的磨牙间距离来计算。数据采用协方差分析（固定因素：面部形态、性别；协变量：体重指数（BMI）；α = 0.05）进行分析。
三种面部形态之间的MOF或MMF均未发现显著差异（分别为P = 0.62和P = 0.72）。BMI对于MOF或MMF不是显著的协变量（P > 0.05）。性别仅是MOF的显著因素（P = 0.007）；男性的MOF值高于女性。
这些结果表明，在这个巴西样本中，MOF和MMF不会随垂直面部形态而变化。
