Partial dentures 5 Flashcards
- abutment teeth are unsuitable for support or retention
- undercuts not allow a normal path of insertion
- bony undercuts anteriorly and wherever we have a flange won’t be able to get into the undercut area easily unless we change the path of insertion
Normal path of insertion for denture is perpendicular to the occlusal plane
- Flange will not go into area as it cannot pass through solid area
What are problems with Upper Kennedy class IV
- Lack of support
- support needs to be gained through
covering a larger surface area
using a cobalt chrome framework with occlusal rests to provide support
Cingulum rest on the 3
Would not put rest on lateral as they are so small and roots cannot tolerate extra load
No clasps on those teeth
Avoid spoon dentures as the palatal connector doesn’t cover large SA
Will lead biting down forces on denture teeth applying pressure to mucosa directly underneath
Have a fully collatve denture
Provides more support for whole surface of palate
Collate going across teeth on surface lines
Expense of oral hygiene
Better result
Cobalt chrome denture
Tooth support form rest
Canines are fine
Support form the 6s
Support for the palate as well
Gingival clearance advantage
Gingival health better in a patient
Design shown here
Patient is missing 2,1,1,2
Majority of support coming from elsewhere
Cingulum rests are not effective in that case
5 missing anterior teeth
Only room to replace 4 teeth in space available
Not available support and retention
Denture has plenty of support coming from all areas
Covers a large surface area
Describe the altered path of insertion
Direction denture comes out of the mouth
Don’t want the denture to come out while the patient is eating
Direction of pull is perpendicular to the plane
Path of insertion should be same and path of displacement
How do we use a initial survey
Surveying
Occlusal plane is horizontal
Use surveyor
All surveyor tools is perpendicular to the plane
what is the path of insertion
What is an analysing rod
Straight metal rod to identify undercut areas without using the graphite marker
Use to scout around the model
What is the initial survey with occlusal plane horizontal
Use analysing rod
Notice anterior bony undercut
Denture flange in the area
Tilt model so that area is no longer undercut
Change direction looking at undercut
Follow this path of insertion
Path of displacement perpendicular to the occlusal plane
Flange also offering retention
Increase retention of denture
Survey model twice
Once with occlusal plane
And once following tilt
Get two survey lines
True area of undercut beneath both lines
Occlusal line horizontal after one path of displacement
What does the altered path of isnertion solve the problem of
Help with black triangle problem
Dentures are solid object cannot go into undercut areas which then creates the black triangles
Altered path of insertion - denture no longer go into the route
Back triangles be covered by the flange
Flange now into undercut area
Spaces further back due to path of insertion that are opened up and appear as black triangles
Describe what happens if the denture as no retention
Dentures
No anterior clasps
Clasps only posterior
Drop down at that end
Clasp is retentive it will still grip onto the teeth the saddle isn’t
Denture
Rotate around the clasp grip
What is a clasp axis
Process of denture design
4 corners of support
Retention
Reciprocating arch
Lack anterior retention
Indirect retention si to create a clasp axis
Anything in front of the line can drop down
Anything behind the line, it will be pushed up as the anterior saddle drops down
Exchange the denture design
Added some rests onto the seven
Taken connector further back
Back here - indirect retainer
Rests and connector
Draw through clasp axis and look other side of it
Shaded area
On Top of flat surface is indirect retainer
Fuerther it is away for clasp axis , more effective it si
Rests at back are effective indirect retainers
what is the best way to face the clasp tips
Large area to put something to act as indirect retention
Extension connector to vibrating line
Sufficient retention
2 clasps
Anterior saddle should not drop
- LESS INDIRECT RETENTION ACHIEVED IF THE CLASP TIP POITN BACKWARDS
What are milled crowns
If patient needs crowns
Incorporate crowns into denture design
Designed so cobalt chrome framework cna fit snugly into those parts of the metal crown
What affects the aesthetics of anterior teeth
How do we determine the position of anterior teeth
How much teeth push out the top lip
Incisal level- how far teeth come down
Horizontal plane parallel with interpurpilalry lien - don’t at teeth to slop
e up or down as we look at the patient from the front
What is the lip support
Lip support
Looking At patient to see what looks right for them
Nasolabial angle
Top lip is straight line
Bottom of nose is another straight line
Angle the both liens should be around 90 degrees
How do we get the correct lip support
- add or remove wax labially to achieve a correct naso-labial angle
- put in patients mouth and look at nasa labial angle
- add wax onto the rim
complete denture patient
How do we get the incisal length correct
- wax rim in patients mouth
where those teeth are going t come down too
height wax rim to be - recreate wax rim level
Remove wax or add wax on
If we want teeth to be shorter
Adjust it till we get right level of tooth showing
Lot of other teeth to give us a clue
Large anterior saddle
1-2mm
