2/21: Posselt's Envelope of Movement Flashcards
What is centric relation?
Position of the mandible in which the condyles are in the most superior and anterior position in the articular fossae, resting against the posterior slopes of the articular eminences
What is the condyle determined position?
Centric relation
When the mandible is in centric relation the condyles can rotate around a horizontal axis up to an opening of _________ mm measured at the central incisors
20-25mm
What is pure rotational movement referred to? And the axis is referred to as?
Hinge movement; terminal hinge axis
What is maximal intercuspal position?
Maxillary and mandibular teeth make maximum surface contact with eachother
- the mandible is elevated as superiorly as possible in the sagittal plane
What is a tooth determined position?
Maximal intercuspal position or maximum intercuspation
What position doesn’t provide any information about the TMJ?
MI
In most people, ______ does not coincide with ______
MIP; CR
Describe the condyle-disc assembly in MIP?
Condyle assembly is anterior and inferior and/or medial or lateral or a combination of the above compared to their position in CR
What position are restorations made in with minimal restoration (e.g., amalgam or composite resin restorations, single crowns, etc)?
Maximum intercuspation
What is postural pisition?
Habitual postural of the mandible when the patient is resting comfortably in the upright position and the condyles are in a neutral unstrained position in the glenoid fossae
Where is there an equilibrium in postural position?
Equilibrium between the forces acting on the mandible
How are muscles in postural position?
Not totally relaxed; there is a degree of electromyographic activity
What is postural position determined by?
The muscles and the forces of gravity
What does postural position NOT give us information on?
Condyles or the teeth
How are the teeth positioned in postural position?
Teeth are apart and there is a wedge space between the teeth
What is the wedge shaped space called?
Interocclusal space and is usually 2-3mm between the incisors, 2mm between the premolars, and 3/4-1mm between the molars
What is postural position aka physiological rest position clincially used to determine?
The occlusal vertical dimension (OVD) in edentulous patients or in patients with severly warn dentition
What is the occlusal vertical dimension?
Distance measured between two points when the occluding members are in contact
Compare the vertical dimension at rest and the occlusal vertical dimension
The vertical dimension at rest (in the physiological rest position) is usually 2-3mm greater than the occlusal vertical dimension
What are the types of movement?
Rotation
Translation
Combination of both
What are mandibular movements limited by?
Ligaments, the articular surfaces of the TMJ and the morphology and alignment of the teeth
What is the outer range of movements called?
Border movements
When do functional movements occur?
During functional activity of the mandible
What are functional movements confined within?
Border movements
When do functional movements begin and end?
In the maximum intercuspation position
What are movement components of posselt’s envelope of movement?
Posterior opening border
Anterior opening border
Superior contact border
Functional movements
What is envelope of motion a combination of?
Border movements in all 3 planes:
A. Sagittal
B. Horizontal
C. Frontal
What happens during opening of the mouth in posterior opening border movement?
The condyles will move forward and down the articular eminence
When is maximum opening reached?
When capsular ligaments prevent further movement
What does anterior opening border movement represent?
The movement from maximum opening to maximum protrusion
What ligaments is maximum protrusion determined by?
Stylomandibular ligaments
Where are the condyles in anterior opening border movement?
Most anterior position
Where does initial tooth contact occur in superior contact border movement?
Between the mesial inclines of the maxillary teeth and the distal inclines of the mandibular teeth
Where does the mandible move in superior contact border movement?
From MIP to edge to edge
What is the mandible movement determined by in superior contact border movement?
The lingual surfaces of the maxillary anterior teeth
What does continued forward movement of the mandible, with the anterior teeth in contact result in?
Superior movement guided by the lingual surfaces of mandibular anterior teeth
What are continued forward movement of the mandible guided by?
The posterior teeth until the mandible reaches maximum protrusion
Where does the chewing stroke start at? then where does it go?
MIP and drops downwards and forwards to the position of desired opening
What shape pattern is the border and functional movements in the horizontal plane?
Rhomboid shaped pattern
What four movement components make up horizontal plane?
- Left lateral border
- Continued left lateral border with protrusion
- Right lateral border
- Continued right lateral border with protrusion and functional movements
What does contraction of the right inferior lateral pterygoid cause?
The right condyle to move anteriorly and medially
The left interior lateral pterygoid relaxes
Left condyle: Rotating or working condyle
Right condyle: Orbiting or non-working or balancing
What happens in the left lateral border with protrusion?
From the left lateral the left inferior lateral pterygoid starts to contract (the right stays contracted) and causes the left condyle to move anteriorly and to the right to maximum protrusion
Where do functional movements occur?
Near MIP
When are the outer range of movements greater?
In the early stages of mastication
When are the outer range of movements smaller?
In the late stages of mastication
What pattern of the border and functional movements of the frontal plane follow?
Shielf-shaped pattern
What are the four distinct movement components of the frontal plane?
- Left lateral superior border
- Left lateral opening border
- Right lateral superior border
- Right lateral opening border
What is the maximum lateral border position determined by?
The ligaments of the rotating condyle
What is the superior surface of the envelope determined by?
The tooth contacts
What are borers primarily determined by?
TMJ anatomy and the ligaments
- What is the name of this envelope
- Define the position of all the numbers and letters
- What does it represent
- Posselt’s envelope
- CI
- MI
- Protrusion
5-3. Maximum opening
R. Postural position
