Fig 1.
Digital models of the upper and lower first molars.
a) Segmented model of lower right first molar (M1, bottom) and upper right first molar (M1, top). Section is through the mesio-distal axis of the teeth. b) FE mesh in distal view. PDL = periodontal ligament; EDJ = Enamel-dentine junction. B = buccal; D = distal; L = lingual; M = mesial.
Fig 2.
Occlusal view of the oriented lower right first molar (RM1).
The tooth is aligned with the cervical plane parallel to the xy-plane of the Cartesian coordinate system, and the mesial side parallel to the y-axis. B = buccal; D = distal; L = lingual; M = mesial.
Fig 3.
Collision detection for RM1 with the antagonist RM1 in the Occlusal Fingerprint Analyser software (OFA) during maximum intercuspation contact.
a) The RM1 is transparent to show the collision (red areas) in the occlusal surface of the RM1; the recorded power stroke pathway trajectory of the RM1 (summarized by the two arrows) is subdivided into an incursive (black arrow = phase I) and an excursive (dashed arrow = phase II) vector. b) The mastication compass visualizes the spatial orientation of phase I and II. The length of the two arrows informs about the inclination angle (after [31]).
Fig 4.
The trajectory of the power stroke.
Trajectory (x-, y- and z-axes) obtained for the RM1 during the chewing cycle (i.e., close + power stroke + open) in the OFA software scaled to the duration of the power stroke (t = 289 ms).
Table 1.
Elastic properties of isotropic materials.
Table 2.
Density of tissues (ρ) and speed of sound (Vsound).
Fig 5.
Contact forces (N) obtained during the non-linear dynamic FE crash colliding test.
The four points in the plot correspond to the time steps at 0.335s (a), 0.375s (b), 0.394s (c) and 0.425s (d) discussed in the text and in Figs 8 and 9.
Fig 6.
Displacement at a point (P), randomly selected in the occlusal surface of the RM1, during the non-linear dynamic FE crash colliding test. Note that the x-axis corresponds to the mesiodistal direction, the y-axis to the buccolingual direction and the z-axis to the crown-root direction.
Fig 7.
Displacement at a point (Q), randomly selected in the occlusal surface of the RM1, during the non-linear dynamic FE crash colliding test. Note that the x-axis corresponds to the mesiodistal direction, the y-axis to the buccolingual direction and the z-axis to the crown-root direction.
Fig 8.
The maximum principal stress distribution observed in RM1 at 0.335s (a), 0.375s (b), 0.394s (c) and 0.425s (d). See Fig 5 for the corresponding times during the power stroke. Arrows on the enamel are elemental contact forces. B = buccal; D = distal; L = lingual; M = mesial.
Fig 9.
The maximum principal stress distribution observed in RM1 dentine (left) and the maximum principal strain distribution observed in RM1 PDL (right) at 0.335s, 0.375s, 0.394s and 0.425s.
See Fig 5 for the corresponding times during the power stroke.