Posselt's envelope of motion

Posselt's Envelope of Motion

Posselt's Envelope of Motion in the Sagittal View

Posselt's envelope of motion is a concept in dentistry and dental anatomy that describes the range of motion of the mandible (lower jaw) in relation to the maxilla (upper jaw). This concept is crucial for understanding the dynamics of jaw movement and is used in the study of occlusion and prosthodontics.

History

The concept was first introduced by Dr. Ulf Posselt in the 1950s. Posselt conducted extensive research on mandibular movements and described the three-dimensional space within which the mandible can move. His work laid the foundation for modern studies of jaw function and occlusion.

Description

Posselt's envelope of motion is a graphical representation of the maximum range of mandibular movement. It is typically illustrated in three planes: sagittal, frontal, and horizontal.

Sagittal Plane

In the sagittal plane, the envelope of motion is depicted as a two-dimensional diagram showing the range of movement from the maximum protrusion to the maximum retrusion of the mandible. The diagram also includes the maximum opening and closing movements. The sagittal view is often used to demonstrate the path of the incisal edges of the lower anterior teeth as they move in relation to the upper anterior teeth.

Frontal Plane

In the frontal plane, the envelope of motion illustrates the lateral movements of the mandible. This view shows the side-to-side movements, which are important for understanding the function of the temporomandibular joint (TMJ) and the balance of occlusal forces during chewing.

Horizontal Plane

In the horizontal plane, the envelope of motion is depicted as a diagram showing the rotational movements of the mandible. This view is crucial for understanding the rotational capacity of the mandible around the vertical axis, which is important for mastication and speech.

Clinical Significance

Understanding Posselt's envelope of motion is essential for dental professionals when diagnosing and treating occlusal disorders. It helps in designing dental prostheses, such as dentures and dental crowns, that accommodate the natural range of mandibular movement. It is also used in orthodontics to plan treatments that align the teeth and jaws properly.

Related Pages

• Occlusion (dentistry)
• Temporomandibular joint
• Prosthodontics
• Orthodontics
• Mastication