Determinants of Balanced Occlusion in Dental Prosthodontics

Determinants of Balanced Occlusion

Condylar Guidance

This includes condylar movements from inside to outside of the glenoid fossa.

• Anteroposterior Guidance: Describes the downward and forward movement during protrusion. It is defined by an angle relative to the horizontal plane, determined by the inclination of the posterior wall of the glenoid eminence. A steeper tilt angle increases the downward movement.
• Lateral Condylar Guidance: The mediotrusive condyle moves downward, forward, and toward the midline, known as the Bennett angle during lateral movement. This angle is relative to the sagittal plane and depends on the inclination of the medial wall of the glenoid cavity. A wider angle increases the separation between upper and lower teeth on the mediotrusive side.
• Lateral Deviation: During laterotrusion, a slight lateral deviation occurs relative to the perpendicular of the sagittal plane. This lateral movement of the working-side condyle is described by Bennett.

Incisal Guidance

Incisal guidance is the hypotenuse of a triangle where the legs are the overbite and overjet.

• AP or Protrusive Guidance: An angle formed during mandibular protrusion relative to the horizontal plane.
• Lateral Guidance: Formed on the side of contact during laterotrusion of canines and incisors, creating an angle relative to the sagittal plane.

Note: Increasing overbite increases both guides, while decreasing overjet decreases both guides.

Curves of Compensation

Proper alignment of teeth includes:

• Curve of Spee: A mesiodistal compensating curve that balances separation during protrusion.
• Curve of Wilson: The buccolingual inclination of posterior teeth, which facilitates contact on the mediotrusive side during lateral movement.

Both curves should be adjusted to maintain contacts in proportion to the decrease in mediotrusive interference during mandibular protrusion.

Hanau Plane Guidance

This factor, often referred to as the orientation of the occlusal plane, includes:

• The distance from the interincisal point to the intercondylar line.
• The distance from the interincisal point to the sagittal plane.
• The orientation of the plane, which passes through the interincisal point and the buccal groove of the second molar.