Station Exam- Part II Flashcards
What are the uses of the articulator?
- diagnosis
- treatment planning
- communicate with patients/patient education
- fabrication prosthesis/restorations
What are characteristics of semi-adjustable articulators?
- used the most
- allow opening and closing movements
- allow excursive (lateral) and protrusive movements
What are characteristics of non-adjustable or “hinge” articulators?
- allow only opening and closing movements
- can be used for single posterior restorations
- their use can create a change in the closure angle- and by doing so the final restoration will present premature contacts
Describe and Arcon semi-adjustable articulator:
- condyles in lower member
- condylar inclination in the upper member
When the condylar indication is in the _____ member , this closely resembles the patients mouth
upper member
Describe a Non-Arcon semi-adjustable articulator:
- mainly used for removable prosthodontics
- condyles in upper member
- condylar indication in the lower member
What type of articulator is ours?
Arcon (semi-adjustable)
- condyles in lower member and condylar inclination in upper member
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 ____ as the articulator
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 and 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 and reproducible. It is parallel to the upper and lower arms of the articulator
The facebow orients a maxillary cast to the:
reference plane
The reference plane requires 3 points including:
2 on each side of face, and one on the anterior face
When should you use a facebow?
- when cusp teeth are present,
-I nterocclusal records are made at an increased occlusal vertical dimension - the OVD is subject to change
- alterations 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 mid-palatal suture
What is the superior border of the maxilla?
floor of nasal cavity and orbit
What is the inferior border of the maxilla?
palate and alveolar ridge
What are the components of the maxilla ?
body and processes (zygomatic, frontal, alveolar, and palatine)
True or false; the maxilla 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 and teeth
What is the posterior aspect/body of the mandible?
mandibular angle and ascending ramus
What makes up the ascending ramus?
coronoid process and condyles (where protrusions and lateral movements of the mandible occur)
What do the condyles articulate with?
cranium
What is the mediolateral length of the condyles?
15-20mm
What is the anterior-posterior width of the condyles?
8-10mm
What does the squamous portion of the temporal bone articulate with?
mandibular condyle
What is the articular eminence function?
Thick dense bone to tolerate heavy forces
What are the muscles of mastication?
masseter, temporalis, medial pterygoid, lateral pterygoid
what are the 2 heads of the masseter and how do their fibers run?
A- superficial head: fibers run downward and backward
B- Deep head: fibers run in vertical direction
What are the 3 distinct divisions of the temporalis and how do their fibers run?
A- anterior: fibers run vertically- only does elevation
B- middle: fibers run obliquely across the lateral aspect of the skull- does elevation and recursion
C- posterior: fibers run horizontally and come forward above the ear to join other temporalis fibers- only does retrusion
What are the two heads of the lateral (external) pterygoid?
Superior lateral pterygoid- smaller
Inferior lateral pterygoid- extends backwards, upwards, and outward
almost two separate muscles!
What is the function of the masseter?
- elevates the mandible
- provides force for chewing
- Superficial head: aids in protrusion
- Deep head: stabilizes the condyle against the eminance
The superficial head of the masseter aids in:
protrusion
The deep head of the masseter:
stabilizes the condyle against the eminance
What is the functions 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 recursion of the mandible
What is the function of the medial (internal) pterygoid?
- elevates the mandible
- protrudes the mandible
What does unilateral contraction of the the medial pterygoid result in?
mediotrusion (mandible moves toward the midline)
What does bilateral contraction 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?
causes mediotrusive movement (downward, forward, & medially)
When is lateral pterygoid superior lateral head in active?
inactive during mandibular opening
When is the lateral pterygoid superior lateral head active?
with elevator muscles (closure of the mandible)
What muscle is involved in the power stroke?
lateral pterygoid superior head- active during mandibular closure against resistance
What two muscles of mastication form the masseter sling, and what is its function?
masseter and medial pterygoid, function to keep mandible in place and stabilize it
What is the function of the suprahyoids?
elevate the hyoid bone and depress the mandible when the hyoid bone is fixed
Depression of the mandible involves contraction of what muscles?
Depression of the mandible involves relaxation of what muscles?
inferior lateral pterygoid and digastric
masseter, medial pterygoid and temporalis
Elevation of the mandible
involves contraction of what muscles:
involves relaxation of what muscles:
contraction: masseter, medial pterygoid, temporalis, and superior lateral pterygoid
relaxation: Inferior lateral pterygoid and digastric
Right lateral movement of the mandible involves:
contraction of:
relaxation of:
contraction: left inferior lateral pterygoid
relaxation: right inferior lateral pterygoid and slight relaxation of elevators
Left lateral movement of the mandible involves:
contraction of:
relaxation of:
contraction: right inferior lateral pterygoid
relaxation: left inferior lateral pterygoid and slight relaxation of pterygoids
Protrusion of the mandible (moves mandible forward in straight line):
contraction of:
relaxation of:
contraction: mainly inferior lateral pterygoids assisted by masseter and medial pterygoids
Relaxation: N/A
Retrusion of the mandible (mandible does back) involves:
contraction of:
relaxation of:
contraction: temporalis
relaxation: N/A
