Figure 1. Mechanical schemes. (A) Force vectors involved in numerical models of isometric biting in humans. Forces on the mandible (e.g., vertical bite force), at the joints (F_condyle, R = right, L = left), and representing 5 muscle pairs (m_1,2 = masseter, m_3,4 = anterior temporalis, m_5,6 = lateral pterygoid, m_7,8 = medial pterygoid, m_9,10 = anterior digastric muscles), plus the axis system, are shown. (Modified from Smith et al., 1986). (B) Equivalent moments for in vivo (1) and modeled (2) molar (+ M_x) and incisor (+ M_z) biting tasks. Line diagrams illustrate mesial views of mandibular right first molar (top) and left central incisor (bottom) with acrylic crowns in place, where: CR is the center of resistance of the tooth/teeth, r is the moment arm vector, _y is the angle away from vertical, and _xz is in a plane parallel to the occlusal plane.

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