Biomechanical analysis for total mesialization of the mandibular dentition: A finite element study

Abstract

Objectives To clarify the mechanics of tooth movement in mesialization of the whole mandibular dentition when changing the force angulation. Setting A finite element method was used to simulate long‐term movements of the whole mandibular dentition. Material and methods Tooth movement was simulated by accumulating the initial displacement, which was produced by elastic deformation of the periodontal ligament. Mesial forces of 3 N were applied to the second molar bracket at −30°, −15°, 0°, 15° and 30° to the occlusal plane. Results The whole dentition and occlusal plane were rotated depending on the direction of the force with respect to the centre of resistance (CR). At a force angulation of −30°, the line of action of the force passed near the CR, and the whole dentition translated without rotation of the occlusal plane. The second molar tipped buccally due to a clearance gap between the archwire and bracket slot. When increasing a force angulation from −30°, the line of action of the force passed above the CR, and thereby, the occlusal plane rotated clockwise. This rotation of the whole dentition induced tipping of the individual teeth. Buccal tipping of the molar due to an elastic deformation of the archwire was prevented by using a lingually pre‐bent archwire. Conclusions Careful selection of force angulation and biomechanics is essential to obtain proper tooth movement in total mesialization of the mandibular dentition.

The changing of occlusal plane inclination in Class II malocclusion

“…Class II elastic is often used in treating patients with skeletal Class II malocclusion, which can cause rotation of the occlusal plane downward and backward. 16,18,21 There was a significant increase in the mandibular incisor inclination (L1-MP/°) and vertical position of mandibular first molars (L6-MP (mm)) before and after non-extraction treatment in this study. These results correlate with the findings of Janson et al 22 which have shown that there was a change in the mandibular incisor inclinations to the anterior and extrusion of the mandibular first molar.…”

Effect of mass variation on vibration properties of the tooth in drilling operation

“…Assuming the numerical data D = 2 mm, f r = 0.05 mm/rev, m 0 = 1.32 g given in 22 , the mass variation is . Based on the measured value of the elastic force in the tooth it is obtain that the order of nonlinearity is α = 1.03 23 and the rigidity coefficient is approximately k = 1 g/s 2 . Substituting the mass relation the equation of motion ( 7 ) is with initial conditions where is the initial deflection and is the initial velocity due to impact between the tooth surface and the drilling tool.…”

Effect of Mass Variation on Vibration Properties of the Tooth in Drilling Operation

“…Assuming the numerical data D=2 mm, fr= 0.05 mm/rev, m0=1.32 g, v=15 m/min, the mass variation is = 1.32 − 0.002 . Based on the measured value of the elastic force in the tooth it is obtain that the order of nonlinearity is α=1.03 [22] and the rigidity coefficient is approximately k=1 g/s 2 . Substituting (35) the equation of motion ( 7) is Applying the Runge Kutta procedure the numerical solution of the equation (36) is computed.…”

“…32 − 0.002 )̈+ | | 0.03 = 0.002̇+ 0.02(22) with initial conditions (0) = 0 = 0.02 ,̇(0) = 0 = 0.5 , where 0 is the initial deflection and the function ( ) = 0.98557 −0.50372 .…”