Fixed pros Flashcards
What is an articulator?
A hinged mechanical device to which maxillary and mandibular casts are attached.
What is the aim of an articulator?
To reproduce as closely as possible the relationship of a patient’s maxilla to mandible in RCP or ICP.
2 reasons to use articulators?
- Diagnostic study casts during treatment planning.
- May facilitate laboratory technician appropriately shaped crowns, bridges and dentures with functional occlusal schemes.
4 types of articulator?
- Simple hinge.
- Average value.
- Semi adjustable.
- Fully adjustable.
Simple hinge?
plane line
average value?
freeplane.
define occlusion?
the way the maxillary and mandibular teeth come together.
What are the splints for bruxism called? Maxillary? Mandibular?
STABILIZATION splints.
- Maxillary: michigan splint.
- Mandibular: tanner appliance.
Simple hinge articulator (4)?
- Equivalent to holding casts in hands.
- Occlusal relationship only correct when casts are together.
- Opening arc is determined by hinge design and is the same for all casts mounted (different from that of patient).
- Lateral and excursive movements not possible.
Average value articulator (6)?
- Sufficiently accurate for reproducing ICP.
- Condylar incilnation is set by manufacturer and cannot be changed.
- Allow for some degree of protrusive and lateral movements.
- OK for posterior restorations where there is obvious guidance from OTHER teeth (ex. canines).
- Complete/ partial removable prostheses - balanced occlusion.
- Movement of cast is NOT accurate to patient movement.
2 cases where an average value articulator may be used?
- OK for posterior restorations where there is obvious guidance from OTHER teeth (ex. canines).
- Complete removable prostheses - balanced occlusion.
3 things that can be adjusted and 1 that cannot be adjusted in semi- adjustable articulators?
- Adjustment of condylar inclination.
- Bennett movement.
- Bennet angle.
- Cannot adjust inter-condylar distance.
2 types of semi-adjustable articulators?
- Arcon (Denar).
- Non arcon (Dentatus).
What is an arcon articulator?
Condylar component is attached to the MANDIBULAR member of the articulator and glenoid fossa is attached to the MAXILLARY member.
What is a non-arcon articulator?
Condylar component is attached to the MAXILLARY component.
Is arcon or non arcon more anatomically correct?
Arcon (denar).
What are arcon articulators used for?
Fixed prostheses work.
What are non arcon articulators used for?
Removable prostheses.
What cases are semi-adjustable articulators used for (5)?
- Multiple units (ex. involved in guidance).
- Re-organised occlusion (ex. increasing vertical dimension).
- Group function (teeth involved guide the mandible).
- Anterior guidance.
- Occlusal analysis.
2 things needed to mount maxillary and mandibular casts onto an articulator?
- Facebow registration.
- Interocclusal record.
Define terminal hinge axis
An axis through the centre of the head of both condyles when they are in the most POSTERIOR/ANTERIOR? and SUPERIOR UNSTRAINED position in the glenoid fossa.
Centric relation?
Maxillomandibular relationship INDEPENDENT OF TOOTH CONTACT in which the condyles articulate in the anterior superior position against the posterior slopes of the articular eminences - UNSTRAINED, PHYSIOLOGIC
What is the first tooth contact called when the mandible closes in the terminal hinge axis position?
Retruded contact position.
When would you use a simple hinge articulator as opposed to just holding the casts in your hand?
When there are unsupported posteriorly/anteriorly due to missing teeth. Would use WAX RECORD BLOCKS to achieve this.
Where is RCP relative to ICP?
Approximately 1mm posterior and inferior to ICP.
Why is RCP important?
Gives us space in a worn dentition within a functional envelope.
What is the theory of mandibular movement called?
Posselt’s envelope of movement.
Condylar inclination?
When a patient postures forward from a retruded or intercuspal position, the condylar head moved DOWN AGAINST THE ARTICULAR EMINENCE –> CONDYLAR ANGLE.
In what position do we want the condyle when we are recording the condylar angle?
Record position in RETRUDED and INTERCUSPAL (or slightly protruded) POSITION
What is a gothic arch?
When the most posterior position is ICP.
During a lateral excursion, what happens to the condyle on the working side? What is this called?
Moves LATERALLY –> BENNETT MOVEMENT.
During a lateral excursion, what happens to the condyle on the non working side? What is this called?
Condyle moves MEDIALLY, FORWARD AND DOWNWARDS –> BENNETT ANGLE.
Things we can change on a semi-adjustable articulator (3)?
- Bennett angle.
- Bennet movement.
- Condylar angle.
Things we cannot change on a semi-adjustable articulator (2)?
- Shape of the condylar movement (cannot have sigmoidal path - it is straight line).
- Intercondylar distance.
What is a facebow?
Calliper like device that records the relationship of the maxilla to the terminal hinge axis (position of condyle).
Bite fork?
Record position of teeth (maxilla).
Bow?
Record position of the terminal hinge axis (condyle)
Jig?
To link bite fork and bow.
Pointer?
- 3rd reference point, to align the teeth to the horizontal axis (frankfurt plane).
Where do you place the pointer?
- Incisal edge of lateral incisor or canine.
- If edentulous upper border of lower lip.
What is the distance to record from the pointer?
42mm
How should the bitefork come out?
To the side of the OPERATOR (right of the patient).