Station Exam Pt. II Flashcards
What are the uses of an articulator:
- Diagnosis
- Treatment planning
- Communicate with patients/patient education
- fabrication of prostheses/restorations
What are characteristics of semi-adjustable articulators?
- Used the most
- Allow for opening/closing
- Allow excursive (lateral) & protrusive movements
What are the characteristics of a non-adjustable or “hinge: articulator?
- Allow only opening/closing movements
- Can be used for single posterior restorations
- Their use can change the closure angle and by doing so the final restoration will present premature contacts
Describe an Arcon semi-adjustable articulator:
- Condyles in lower member
- Condylar indication in upper member
When the condylar indication is in the ______ member, this more closely resembles what is in the patients mouth
Upper member
Describe a Non-Arcon articulator:
- mainly used for removable prosthodontics
- Condyles in upper member
- Condylar inclination in the lower member
What type of articulator do we use?
Arcon (Semi-adjustable)
What is the purpose of a facebow?
To orient the maxillary cast to the rotational axis in three planes
Using a facebow will result in _____ articulation of subsequent _____ casts
Reproducible; maxillary
The facebow orients the dental cast in the same relationship to the ______of the aritculator
opening axis
What are usually the anatomic references?
- Mandibular condyles
- Transverse horizontal axis
- One other selected anterior point
What does an ear-bow index to & what does it register?
The external auditory meatus; Registers the relation of the maxillary arch to a horizontal reference plane
What is the third point of reference?
The anterior reference point- it should be repeatable & reproducible; it is parallel to the upper and lower arms of the articulator
The facebow orients the maxillary cast to a:
Reference plane
The reference plane requires 3 points including:
2 on each side of the face and one on the anterior face
When should you use a facebow?
- When cusp teeth are present
- Interocclusal records are made at an increased OVD
- When the OVD is subject to change
- Alteration in occlusal surfaces are necessary
Where does the mandible articulate with the skull?
At the temporal bone
How many bones make up the maxilla and where do they fuse?
Two; fuse at the mid-palatal suture
What is the superior border of the maxilla
The floor of the nasal cavity & orbit
What is the inferior border of the maxilla?
The palate & the alveolar ridge
What are the components of the maxilla?
Body & processes (zygomatic, frontal, alveolar, palatine)
T/F: The mandible is the largest and strongest bone in the skull
True
What are the components of the mandible?
Body (horizontal part)
Ramus (Vertical part)
What is the superior aspect of the mandible:
Alveolar crest & teeth
What is the posterior aspect/bodt of the mandible:
The mandibular angle and ascending ramus
What makes up the ascending ramus?
Coronoid process and condyle (where protrusions & lateral movements of the mandible occur)
What do the condyles articulate with?
Cranium
What does the squamous portion of the temporal bone articulate with?
The mandibular condule
What is the function of the articular eminence:
Tolerate heavy forces
What are the muscles of mastication?
Masseter
Temporalis
Medial Pterygoid
Lateral Pterygoid
What are the two heads of the masseter and how do their fibers run?
Superficial head: downward & backward
Deep head: vertical
What are the three distinct divisions of the temporalis and how do they fibers run?
Anterior: fibers run vertically- only does elevation
Middle: fibers run obliquely across lateral aspect of skull- does elevation & retrusion
Posterior: Fibers run horizontally & come forward above ear to joint other temporalis fibers- only does retrusion
What are the two heads of the lateral (external) pterygoid?
Superior lateral pterygoid (smaller of the two bellies)
Inferior lateral pterygoid (Extends backward, upward & outward)
Masster action:
- Elevates the mandible
- Provides force for chewing
- Superficial head: aids in protrusion
Deep head: stabilizes condyle against the eminence
What is the function of the ANTERIOR temporalis:
Raises mandible vertically
What is the function of the MIDDLE temporalis:
Elevates & retrudes the mandible
What is the function of the POSTERIOR temporalis:
Aids in retrusion of mandible
What is the function of the medial pterygoid:
-Elevates the mandible
-Protrudes the mandible
What does unilateral contraction of the medial pterygoid result in?
Results in mediotrusion (mandible moves towards midline)
What does bilateral contaction of the lateral pterygoid inferior head result in?
Causes condyles to be pulled down the articular eminences and the mandible is protruded
What does unilateral contraction of the lateral pterygoid inferior head result in?
Mediotrusive movement (downward, forward, medially)
Describe the power stroke of the lateral pterygoid superior head:
This muscles is active during mandibular closure against the resistance of chewing
What muscles of mastication form the masseter sling, and whats its function?
Masseter & Medial pterygoid- functin to keep mandible in its place and stabilize it
Depression of the mandible invovles:
Contraction of-
Relaxation of-
- Inferior lateral pterygoid
- Digastric
- Masseter
- Medial pteryogoid
- Temporalis
Elevation of the mandible involves:
Contraction of-
Relaxation of-
- Masseter
- Medial pterygoid
- Temporalis
- Superior lateral pterygoid
- Inferior lateral pterygoid
- Digastric
Right lateral movement of the mandible involves:
Contraction of-
Relaxation of-
- Left inferior lateral pterygoid
1.Right inferior lateral pterygoid
2. Slight relaxation of elevators
Left lateral movement of the mandible involves:
Contraction of-
Relaxation of-
- Right inferior lateral pterygoid
- Left inferior lateral pterygoid
- Slight relaxation of pterygoids
Protrusion of the mandible involves:
Contraction of-
Relaxation of-
- Mainly the inferior lateral pterygoids
- Assisted by masseter
- Assisted by medial pterygoids
Relaxation=NONE
Retrusion of the mandible involves:
Contraction of-
Relaxation of-
- Temporalis
Relaxation=NONE
What are the three reference positions in Posselt’s envelope of motion?
CR
MI
Postural position
CR is the position of the mandible in which the condyles are in the most superior and anterior position n the articular fossae, resting against the posterior slopes of the articular eminences with the articular discs ______
Interposed
When the mandible is in CR, the condyles can rotate around a horizontal axis up to an opening of the mandible of ______ measured at the central incisors:
20-25 mm
If opening of the mouth beyond 20-25mm, then ____ of the mandible occurs
Translation
Pure rotational movement can be referred to as _____ movement
Hinge
In maximum intercuspation, the mandible is _____ as ____ as possible in the sagittal plane
Elevate as superiorly as possible
This position does NOT provide any information in regards to the TMJ
MI
In MIP, the condyle-disc assembly is _____&_____ and/or _____or ____ or a combination of the above compared to their position in CR
Anterior & inferior
Medial or lateral
Usually in MIP the condyle-disc assembly is:
Anterior & inferior
Clinically if the patient needs minimal restorations what position do we put them in?
MI
The habitual postural position of the mandible when the patient is resting comfortably in the upright position & the condyles are in a neutral unstrained position in the glenoid fossa:
Physiological rest position (also called postural position)
In this position there are equilibrium between the forces acting on the mandible:
PP
The physiological rest position does NOT give us any information in regards to:
The condyles or the teeth
In PP the teeth are apart and there is a wedge of space between them, what is this wedge of space referred to as?
Interocclusal space (normally 2-3mm)
Clinically is used to determine the OVD in edentulous patients or in patients with severely worn dentition:
Interocclusal space during PP
The distance measured between two points when the occluding members are in contact:
OVD
Types of mandibular movement:
- Rotation
- Translation
- Combination
The mandible moves in what three planes:
- Horizontal
- Frontal
- Sagittal
The mandibular movements are limited by: (3)
- Ligaments
- Articular surfaces of the TMJ
- Morphology/alignment of teeth
The outter range of movement of the mandible
Border movement
This type of movement occurs during functional activity of the mandible and are confined within the border movements:
Functional movements
Functional movements of the mandible begin & end in:
MI
Border & functional movements in the sagittal plane are usually referred to as:
Posselt’s envelope
List the four movement components of Posselt’s Envelope:
- Posterior opening border
- Anterior opening border
- Superior contact border
- Functional movements
During opening of the mouth, condyles will rotate then translate forward and down the articular eminence
What aspect of posselt’s envelope does this describe?
Posterior opening border movement
During posterior opening border movement:
During opening of the mouth, condyles will _____ & the _____ the articular eminence:
Rotate & then translate forward and down
During posterior opening border movement:
Maximum opening is reached when:
The capsular and temporomandibular ligament prevent further movement
This represents the movement from maximum opening to maximum protrusion
What aspect of posselt’s envelope does this describe?
Anterior opening border movement
During anterior opening border movement:
Maximum protrusion is determined partly by the ______ ligaments
Stylomandibular
During anterior opening border movement, when maximum protrusion is reached the condyles are in the most _______ position
anterior
The initial tooth contact occurs between the mesial inclines of the maxillary teeth & the distal inclines of the mandibular teeth
What aspect of Posselt’s envelope does this describe?
Superior contact border movement
