29. Simulation of the mandible movements. Theories of the mandible movements.

whats in it

what is used for stimulation of mandible movements?

articulators follow which anatomical factors?

bonvill

conical

hall

spherical theory/monson

gysi

theory of helicoid (ackkerman)

articulatros are used for

• for simulation of the mandible movements

• -  Articulators simulate/ represent the TMJ and allows a good representation on how the

  dental prosthesis will function in the patient’s mouth

• -  The articulator simulates the opening and closing of the mouth

0. Mandibular movements are broken down into a series of motions around 3 AXIS’:

   1. Horizontal axis

   2. Vertical axis

   3. Sagittal axis

Articulators fllow which 2 anatomic factors

These theories follow the crucial anatomic factors which are:

• -  Condyle and fossa of the TMJ

• -  Articulating surfaces of the 2 dental arches

bonvill

• Most important movement are the vertical movements (opening and closing)

• -  Claims that the mechanical axis of rotation (hinge axis) is 2.5 cm behind the anatomical axis of rotation

• -  Bonvill theory of equilateral triangle according to the condyles is equal to the distance between the condyle and the midpoint of mandibular incisors 8cm

• -  This articulator only lateral movements and horizontal movements

hall theory theory articulators

hall (1925( - transverse movements

sagitall movements are hard, atifial teeth with flat surfaces

monson curve

he center is at crista Galli (2cm behind the Glabella).
In the center of this theory are:
- Curve of Spee

- Transversal compensatory curve (curve of wilson)

gysi theory

• Theory of movement of the lower jaw around a cylinder

• -  The TMJ having the leading role and the articulating surfaces

  just glide at the lateral movement

6. Theory of helicoid occlusal plane (Ackermann)

• Theory states that teeth have helicoid shape arrangement

• -  Centre of the helicoid is in the region of the upper second premolar

• -  This shape is like a helicopter propeller