Complete Prosthetics Flashcards
When do you complete the jaw registration record?
after primary and secondary impressions
What is jaw relation record?
assessing how the patient is occluding, where teeth should go and how the arches relate to each other
What is centric relation?
maxillo-mandibular relation with muscles relaxed and condyles in the most anterior-superior position in the glenoid fossa
Are teeth contacting in centric relation?
no
Why do we use centric relation?
it is the most reproducible position as it is a position of musculoskeletal stability
For dentures do we want a difference between the retruded contact position an the position of maximum intercuspation?
no, we don’t want the teeth to slide into maximum intercuspation
What do you use to record the jaw registration?
wax rims
What is the first thing you check when you get the wax back from the lab?
that it is smooth with no lumps or sharpness and that the heels of the cast do not touch or interfere with the wax rims
What type of occlusion do we want for complete dentures?
balanced occlusion
What is balanced occlusion?
all teeth in contact at the same time
How can you check stability of the complete denture wax rims?
press on one side and see if it lifts on the other side
What is jaw relation?
relationship of the maxilla to the mandible
Why is it important to make a record of the jaw relation?
there are no teeth so you can’t assess the vertical height otherwise
What can happen if the teeth end up too high in the denture? (the vertical height is increased)
difficulty in function and swallowing, discomfort, elongated face
What can happen if the teeth end up too low in the denture? (the vertical height is decreased)
increased cheek biting, increased chance of angular cheilitis, TMJ pain, mandibular protrusion
Should you look at the mandibular or maxillary wax rim first?
maxillary
What is the first thing you should look at when assessing a wax rim?
the lip support/labial fullness
Why is it important to check the lip support of the wax rims?
to ensure the teeth will be positioned in the neutral zone
What is the neutral zone?
the space between the intra and extra oral muscles where the teeth normally sit
What can happen if the teeth are positioned outside of the neutral zone?
the lips or tongue will push against the teeth and the denture will be unstable
What is the second thing you should look at when assessing a wax rim?
incisal show
What should the incisal show be for the maxillary wax rim?
2mm below the relaxed upper lip and parallel to the interpupillary line
What lines should you mark on a maxillary wax rim?
centre line and canines
Where do you draw the lines to mark the canines on a maxillary wax rim?
either side of the nose
What planes should be parallel when using a foxs plane?
occlusal plane, interpupillary line, ala tragal line
What should the incisal show be for the mandibular wax rim?
at or below the level of the lower lip and angle of mouth
What is vertical dimension?
the amount of separation between the maxilla and mandible
What does RVD stand for?
resting vertical dimension
What does OVD stand for?
occluding vertical dimension
What is freeway space?
the difference between RVD and OVD
What is the average FWS (Freeway Space)?
2-4mm
What tool do we use to measure the vertical dimension?
willis bite gauge
How do we measure the vertical dimension?
with the maxillary wax rim in the patient’s mouth, take four measurements and take the average as the RVD and minus 2-4mm to get the OVD
What are the four measurements we take to get the average vertical dimension?
relaxed, lick the lips, say ‘m’, swallow
Why is it important to record the OVD?
that will give the vertical dimension when the wax rims should be touching and allows you to adjust the height of them to reflect that
Why is it important to record the centric relation of the wax rims once the OVD is accurate?
the mandible tends to protrude if there are no teeth and centric relation is the most reproducible and stable position
How can you record centric relation?
make a couple notches in the wax rims and use silicone to record an impression of how the wax rims fit together in centric relation
Where are the relief areas of the maxilla?
labial frenum, buccal frenum, incisive papilla
Where are the support areas of the maxilla?
residual ridge, palate, maxillary tuberosity, rugae
Where are the relief areas of the mandible?
labial frenum, buccal frenum, lingual frenum, lingual frenum, mental foramen, genial tubercle, mandibular tori, mylohyiod ridge
Where are the support areas of the mandible?
residual ridge, retromolar pad, buccal shelf area
What are primary stress bearing areas?
areas that do not resorb even after loading
What are secondary stress bearing areas?
do resorb but slowly
