Mandibular kinematics in dentofacial deformities before orthognathic surgery

AIM: Changes in facial morphology may cause disturbances in stomatognathic functions. The aim of the current investigation was to quantitatively assess the three-dimensional condylar paths during standardized mandibular movements in patients with dentofacial deformities before orthognathic surgery and in healthy subjects. METHODS: Patients with dentofacial deformity were divided in two groups: DG-II (n = 15 with class II, mean age 26.3 years) and DG-III (n= 15 with class III, mean age 26.2 years), with 3 men and 12 women each, were assessed during the preoperative orthodontic treatment. Fifteen healthy young adults, paired for age and sex, were selected for control group. Mandibular kinematics were recorded during maximum mandibular border movements: mouth opening (MMO) and closing, lateral excursions and protrusion, using an infrared optoelectronic 3D-motion analyzer (BTS SMART System), with a 500 Hz sampling rate. RESULTS: Patients and healthy subjects had similar age (1-way ANOVA, p≥0.05). The DG-II showed larger laterotrusion asymmetry than CG (Table 1). At MMO, the percentage of mandibular movement explained by condylar rotation was larger in the DG-III than DG-II (2-way ANOVA, p=0.001; Bonferroni post-hoc test, p=0.045, Figure.1). CONCLUSION: The outcomes suggest that the proposed method could be a useful diagnostic tool to detect altered function in DG patients before orthognathic surgery. ACKNOWLEDGEMENT: Provost’s Office for Research of the University of São Paulo. *The first author received a scholarship from CNPq (Science without Borders), Brazil. Table 1: Kinematics indices of mandibular motion, mean±SD, 1-way ANOVA. Measure Control DG-II DG-III p-value Mean SD Mean SD Mean SD Maximum opening – MMO (mm) 47.8 4.0 44.8 5.5 46.5 7.2 0.360 MMO deviation (mm) 2.7 1.1 3.6 1.6 3.4 2.3 0.358 Maximum laterotrusion 9.7 2.1 8.9 1.7 8.1 1.7 0.068 Laterotrusion asymmetry 0.7* 0.7 2.6* 2.6 1.1 1.1 0.011 Maximum Protrusion 7.7 1.7 7.4 1.6 6.5 2.0 0.196 *=Bonferroni post-hoc test, p=0.014. Figure 1: Percentage of mandibular rotation during mouth opening and closing