Occlusion Exam 1 Flashcards
“The static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues” is the definition of
Occlusion
“The static and dynamic contact relationship between the occlusal surfaces of the teeth during function” is the definition of
Articulation
What are the two types of movement that the mandible can perform?
Rotational
Translational
Define rotational movement
Turning around an axis
movement of a body about its axis
Define translational movement
All points within a body have a identical movement (same direction and speed)
How many axes of rotation are there?
3 axes of rotation
1. Horizontal
2. Sagittal
3. Vertical
Horizontal axis is perpendicular to the _______ plane
Sagittal plane
The sagittal plane runs perpendicular to the plan of _____
Frontal plane
Vertical axis is perpendicular to the plan of ____
horizontal plane
Pure rotation of the mandible is limited to about ______
20-25 mm
The mandible can rotate around the ________ that runs through both condyles and ________ to the sagittal plane
The mandible can rotate around the HORIZONTAL AXIS that runs through both condyles and PERPENDICULAR to the sagittal plane
Pure rotation takes place between the _______ and the ______
condylar process and articular disk
The mandible translates _____ and _____ during protrusion or if the opening is greater than ~20-25
Downward and forward
Translation takes place between the _____ and the _____
Between the disc and the glenoid fossa
True or false: Translation and rotation occur simultaneously
True
T or F
Movement of the mandible occurs in three planes simultaneously
True
True or False
Axis of rotation is horizontal to the plane of movement
False
Axis of rotation is PERPENDICULAR to the plane of movement
In a right lateral movement, the right condyle is referred to as
the working condyle
(working, rotating, functional)
In a right lateral movement, the left condyle is referred to as
The balancing condyle
(balancing. non-working, non-functional, orbiting)
True or False
In a right lateral movement, laterotrusion is occurring on the balancing condyle
False
Right lateral movement means right condyle is working and left condyle is balancing
Laterotrusion is the lateral translation of the condyle on the working side, in this case the right condyle
Movement that is taking place on the non-working condyle is known as _____
Mediotrusion
Define mediotrusion
medial translation of the nonworking condyle
What is the difference between border movement and functional movement
Border movement describes movements of the mandible in the outer range of motion, they are reproducible describable limits
Functional movement are all the movements that fall within the other range of mandibular movement, they are not reproducible
What is the difference between border movement and functional movement
Border movement describes movements of the mandible in the outer range of motion, they are reproducible describable limits
Functional movement are all the movements that fall within the other range of mandibular movement, they are not reproducible
True or False
Functional movement is reproducible
False
Border movement is reproducible
When in CR, the mandible can only perform protrusive movement
False.
When in CR, the mandible is restricted to pure rotational movement
A maxillomandibular relationship, independent of tooth contact, in which the condyles articulate in the anterior-superior position against the posterior sloped of the articular eminence
Is the definition of
Centric Relation (CR)
From CR, what kind of mandibular movements can the patient make
From CR, the patient can make vertical, lateral, or protrusive movements
True or False
CR is dependent on tooth contact
false
It is a jaw position, not tooth contact
Define maximal intercuspal position (MIP)
the complete intercuspation of the opposing teeth
Is it possible for the mandible to be in CR and the teeth to be in MIP simultaneously?
Yes
Define Centric Occlusion (CO)
The occlusion of opposing teeth when the mandible is in centric relation
CO may or may not coincide with MIP
T or F
In most individuals, CO is the same as MIP
false
Define Initial point of contact
The first or initial contact of opposing teeth during closure of the mandible when in CR.
Usually on mesial inclines of maxillary teeth and distal inclines of mandibular teeth
What incline is IPC usually one in
1. mandibular teeth
2. maxillary teeth
IPC on maxillary teeth: mesial inclines
IPC on mandibular teeth: distal inclines
The movement of the mandible while in CR from the initial point of contact into MIP is called the _____
centric slide
Centric slide has an ______ and ______ direction. This is dictated by the contour of the IPC
Centric slide has an anterior and superior direction
Horizontal overlap (HO)=
overjet
Vertical overlap (VO)=
overbite
Guidance of the mandible from the incisors when the mandible moved in a protruded position from MIP is known as
Incisial guidance
What features determine incisal guidance?
- The horizontal overlap and vertical overlap of anterior teeth
- shape of lingual concavity of the maxillary anterior teeth
The path of the mandible to the maximum protrusive position is the ______
maximum protrusion
Define Maximum mandibular opening
The path from the maximum protrusive position to the maximum opening of the mandible
Define vertical dimension of occlusion (VDO)
also known as “occlusal vertical dimension”
Distance between two selected anatomic or marked points when in maximal intercuspal position
Define vertical dimension of rest (VDR)
Postural position of the mandible when an individual is resting comfortable in an upright position and the associated muscles are in a state of minimal contractual activity
-also known as “physiological rest position”
VDR-VDO=
Freeway space
or interocclusal rest distance
Its the difference between the vertical dimension of rest and the occlusal vertical dimension
What is the envelope of motion?
-The three dimensional representation of mandibular border movements
-represents the maximum range of movement of the mandible
also known as Posselt’s envelope of motion
Functional movements take place within the borders of the _________
envelope of motion
What does determinants of mandibular movement mean?
The anatomic structures in the patient that dictate pattern of mandibular movements
Describe the characteristics of posterior determinants of mandibular movement
- The anatomic characteristics of left and right TMJ’s
- Usually fixed in a healthy patient
- Can be altered under certain conditions (trauma, pathology, surgical procedure)
Describe the characteristics of anterior determinants of mandibular movement
- Anatomy of anterior teeth and their relationship
- Variable determinant
- Can be altered by dental procedures
List the actual posterior determinants of mandibular movement
- intercondylar distance
- Angle of articular eminences (condylar guidance)
- Immediate side shift
- Progressive side shift
- Bennett movement
List the anterior determinant of mandibular movement
Incisal guidance
Describe three things about intercondylar distance
- Its the distance between the rotational centers of two condyles
- measured in mm in the horizontal plane and is on average 110 mm. Its a fixed measure in healthy patients
- The anatomic structures that dictate this distance are the left and right condyles and the distance from each other
What is the angle of articular eminence?
-also called condylar guidance
-the mandibular guidance generated by the condyle and articular disc transversing the contour of the articular eminence
-measured in degrees in the sagittal plane
-affects PROTRUSIVE mandibular movement
-shape and steepness of the articular eminence dictate this determinant
Immediate side shift is a posterior determinant or an anterior determinant?
Posterior
What is immediate side shift
- Also known as immediate mandibular lateral translation
- Its the translation portion of the lateral movement seen in the NON WORKING condyle
- Essentially a straight line medially
What is progressive side shift?
- Its the measure of the forward movement of the non-working side condyle
- Measured in degrees and is called the BENNETT ANGLE - Average value is 6-8 degrees
Bennett angle is measured on the ________ plane and is formed by the ANTERIOR-MEDIAL path of the _________ condyle as it leaves _______ and the sagittal plane.
Bennett angle is measured on the horizontal plane and is formed by the anterior-medial path of the NONWORKING condyle as it leaves CR and the sagittal plane
What anatomic structure dictates progressive side shift?
Angle of medial wall of the articular fossa
Progressive side shift affects the mandibular path during a _______ movement
protrusive or lateral
lateral
What is Bennett movement?
The movement that takes place on the WORKING CONDYLE during lateral movements
Bennett movement takes place due to the combined effect of ____________ and ____________
immediate side shift and progressive side shift
What anatomic structures dictate Bennett movement?
- Laxity of temporomandibular ligament on the working side
- Proximity of medial wall to balancing condyle
In an articulator, the upper member represents the
The maxilla and temporal bone
The lower member represents the
mandible
In an articulator, what feature represents the teeth?
The incisal table
The condyle elements of an articulator are located on the
lower member
How is intercondylar distance distance measured on an articulator
Measure the distance between the two rotational centers of the condyle elements and divide by 2
In the whipmix articulator, the intercondylar distance is (fixed or unfixed) and measures _______
fixed
110/2=55
In the upper member, the left and right fossae elements represent the _______
Squamous portion of the temporal bone
*Fossae elements are adjustable
In an articulator, each fossa element has a ______, _____, and _______
medial, posterior, and superior wall
Medial wall angulation and distance from the balancing condyle affects the path of the mandible during __________ movement
lateral
Balancing side medial wall angulation dictates _______
progressive side shift
Balancing side medial wall distance from the condyle dictates the _______
immediate side shift
What is the immediate side shift value in the whip mix articulator?
zero
The superior wall of the articulator represents the _____
articular eminence
Is the angulation of the articular eminence adjustable in the whipmix articulator?
Yes
This is also called the condylar guidance angle
True or false
In a patient, the articular eminence makes direct contact with the condyle as it does on the whipmix articulator.
False
In a patient the articular eminence does not make contact with the condyle but it DOES in the articulator
The posterior wall of the fossa element in the articulator represents the ______
The wall posterior to the glenoid fossa in patient
In both the patient and the articulator, the posterior wall contacts the condyle as a mechanical stop
False.
Only in the articulator does the posterior wall contact the condyle element
In patients, there is a space between the condyle and the posterior wall.
What feature of the articulator interlocks the upper and lower members and holds the mounted casts
The centric latch
When the centric latch is engaged, what movements can be done? What movements can be down if the centric latch is not engaged?
Engaged: opening and closing movements
Non-engaged: opening, closing, lateral, and protrusive movements
Describe a Hinge articulator
small, nonadjustable, only capable of opening and closing
Results in premature contacts because the distance between tooth and hinge closure is small
Which type of articulator is used most for routine fixed prosthesis?
Semi-adjustable articulators
Which type of articulator is used most for routine fixed prosthesis?
Semi-adjustable articulators
Semi adjustable articulators can be divided into arcon and nonarcon. What are the differences between the two?
Arcon: condyle elements are attached to the lower member and mechanical fossae are attached to the upper. Angulation of mechanical fossae is fixed. Anatomically correct
Nonarcon: Condyle elements attached to upper member. FOP angle can change
True or False: At the start of a left or right lateral movement, the condyle elements will touch all three walls of the fossa elements
True
At the end of the path
The working condyle element maintains contact with which wall(s)?
The balancing condyle element maintains contact with which wall(s)?
Working condyle element: contact with superior and posterior wall
Balancing: medial and superior wall
Mounting casts is a fundamental skill for
- treatment planning
- Diagnostic wax ups
- Working casts
Indications for mounted Dx casts
- not enough teeth to hand articulate
- Exaggerated CR slide
- Interfering contacts
- occlusal surface wax ups
- Incisal guidance wax ups
- Plane of occlusion discrepancies
Did the mounted PKT casts we did in class had anterior slide
No
In class, our casts MI=CR with no anterior slide
Prior to mounting:
1. Set condylar guides to ______ degrees
2. Set Progressive side shift to _____ degrees
Condylar guides: 30 degrees
Progressive side shift: 10 degrees
Maxillary PKT cast will be placed on the _____ to hold it in position
Index
The most accurate method of mounting casts in MI is by __________
hand articulating the mandibular cast in MI
For which step of mounting a PKT cast do you have to invert the articulator?
When mounting the mandibular cast.
What are the 4 ways you can verify the accuracy of your mounting?
- No CR should be present, casts should close exactly to MI
- Contact of both condyles with their back and top walls
- Contact of teeth in MI
- Contact of the incisal pin
Why is the subtractive technique used?
To create a wax up with contacts in maximum intercuspation
T or F
Wax should be cool and dull for smush
F.
Wax should be heated but dull
After the smush, the impression of which 2 teeth were created on #29 and #30?
Impression of #3 and #4
Looking at the smush, which areas of the wax will be cusps and which areas will be fossae?
High areas of wax will be the cusps
Low areas will be fossae
Looking at the smush, why is there overflow of wax on the lingual?
Because those cusps are not in contact with the opposing teeth
What’s the outline form of #29 and #30
29 = square
#30 = pentagon
If there is an interference during working movement when checking your contacts, what should you do
Remove the interference on the periphery of the contact TOWARD the movement
What’s the significance of occlusal relationships?
- Affects basic activities like chewing
- Important in maintaining tooth alignment and arch integrity
- Proper relationship during rest and function protects soft tissue
Describe the ideal static occlusal relationship for posterior teeth
Posterior teeth:
Bucco-lingual alignment: Buccal cusps of post. mandibular teeth occlude with maxillary central fossa. Lingual cusps of maxillary teeth occlude along central fossa of mandibular teeth. Solid contacts present in MIP
Mesio-distal alignment: Cusp-fossa articulation scheme or cusp-marginal ridge articulation scheme
Describe the ideal static occlusal relationship for anterior teeth
Maxillary teeth overlap the mandibular teeth and contact lightly
What are the centric cusp (Buccal or lingual) in mandibular and maxillary posterior teeth
Maxillary: Lingual cusp is centric cusp
Mandibular: Buccal cusp is centric cusp
Define cusp-fossa articulation
An occlusal arrangement where the maxillary and mandibular centric cusps articulate with the opposing fossae in MIP
Where does contact take place in an ideal static occlusal relationship in anterior teeth?
Contact takes place between incisal edges of mandibular anteriors and lingual fossa of maxillary anteriors
True or False: contacts between posteriors are lighter than contacts between posteriors
False.
Contacts between anteriors are lighter
What feature of anterior teeth does not favor heavy occlusal forces?
Anterior teeth slight labial inclination
Define mutually protected articulation:
An occlusal scheme in which the posterior teeth prevent excessive contact of the anterior teeth in MIP and the anterior teeth disengage the posterior teeth in all mandibular excursive movements
Which teeth (posterior or anterior) contact more heavily during MIP
Posterior contact is heavier in MIP
Define excursive movement
movement occuring when the mandible moves away from the maximal intercuspal position (MIP)
Describe ideal articulation during a laterotrusive movement
Ideal: Canine guidance provides disclusion of posterior teeth
Acceptable: Group function provides some disclusion of posterior teeth
Describe ideal articulation during a protrusive movement
Anterior guidance provides disclusion of posterior teeth
Define canine guidance
form of mutually protected articulation in which the vertical and horizontal overlap of the canine teeth disclude the posterior teeth in the excursive movements of the mandible
What is the most ideal articulation scheme in laterotrusive movements
Canine guidance
Why? canines have the longest and largest roots surrounding the bone
only about 26% of pop have ideal
Define group function
multiple contact relations between the maxillary and mandibular teeth in lateral movements on the working side and at the same time contact of several teeth act as a group to distribute occlusal forces
Another term for group function is
unilaterally balanced occlusion
What does the most desirable group function consist of
canine, premolars, and sometime the MB cusp of first molar
True or false:
Incidence of group function increases as people get older
True. This is due to increased canine wear over time
True or False:
In protrusive movement, contacts should be present between posterior teeth
FALSE.
In protrusive movement, no contacts should be present between posterior teeth
Describe the ideal articulation in protrusive movement
Contacts predominantly between incisal edges and labial edges of mandibular incisors and lingual fossa areas of the maxillary incisors
What kind of force placed on teeth can be damaging to tooth and surrounding structures?
Horizontal forces are not effectively dissipated to the bone by the pdl
*force applied vertically is well dissipated to bone and PDL
The process of directing occlusal forces through the long axis of the tooth is what force
Axial loading
Can be achieved by
1. Point contact against a flat plane
2. Bipod contact against opposing inclined planes
3. Tripod contact
When is point contact against a flat surface acceptable?
If the force applied is within the perimeter
Define bipod axially loading contacts
A bipod contact against two opposing incline planes.
What is the most stable occlusal contact?
Three contact points for each centric cusp. Tripod contact where each cusp contacts an opposing fossa such that it is produces three contacts surrounding the cusp tip
Clinically where is tripod contact seen?
In a cusp-fossa relationship
Is a bipod contact against opposing incline planes that result in a force that is not parallel to the long ais of the tooth a bad or ideal
This is bad, this would be a non-axially loading.
