Partial Dentures 6 Flashcards
What are Free end saddles and want do they result in.
Why are lower free end saddle dentures problems
Frequently unsuccessful
Class I lower dentures
Uncomfortable - mucosa supported- transmit forces to the ridge below
Load on abutment teeth
Force transmitted to premolar
Tooth might start to become uncomfortable for a while
Lack of retention
I bar - retain 4 denture teeth
Rely on clasp on premolar to stop denture form lifting out
Discomfort on denture bearing area
Adverse forces on abutment teeth
If this is situation patients teeth apart - everything is fine
Arrow dentures force- patient put food in mouth and chewing on food
Denture pushed into tissue, because supported by toth at one end
Pushed into tissue more at the abc end of the denture
Force on premolar tooth
What is another issue fo not having tooth at the back of denture
Without having tooth at back of denture
May start to move side to side during function
Bracing - denture wraps around patients remaining ridge to prevent that from happening
Denture like a see saw
Bite down at the back , rock over top of rest
Anything in front of premolar will lift up
What are management strategies of lower free end saddle
5-5 upper and lower - function fine
½ premolar missing - may be able by resin retained bridges give resin retained premolars
Reline saddle- make pressure on ridge even
Narrower teeth - more effective than getting through food
RPI - design of denture that reduces torque or twisting forces of the abutment teeth
Revisit indirect retention - anterior saddles
Cant get retention form clasps at either end of saddle
What are the differential pressure impressions for free end saddles
Take pressure off the mucosa . denture sitting on in a compressed state
Special tray - closing fitting and adapted over edentulous area
Snugly fitting mucosa
Describe difference between mucostatic and mucocompressive techniques
1st - pressure concentrated at back of denture if denture was sitting in top of tissues
Even thickness of mucosa even if underlying bone is uneven
Biting pressure spread over much larger surface area
What 2 things do we need to consider for designing free end saddles
Normal processes
Lower free end saddles
Including rpi
Situation may find
Lower free end saddle
I bar
Rest where normally position it
Closest side of abutment tooth to free end saddle
Patient bites down - denture completed on that
Sink down
On the saddle area
Rest on bac edge of pre oalr
Dentures tend to rotate around hat rest
Clasp - i bar on opposite side of rest
Like a see saw
I bar tend to pushed more towards survey line
Survey lien - widest part of the tooth
Pushed upwards- digging in the surface of the tooth
Move rest to mesial tide of tooth than distal -
See saddle and I bar are same side of that fulcrum
When patients bites down
I bar has tendency to move downwards
I bar resting against tooth’s surface moving away from tooth surface
Not applying any stress or abutment tooth
Mesial rest - key part of design process for lower free end saddles
What is the RPI system
1st stage of denture design
First stage - outline saddles
Drawing these - little shape behind teeth - retromolar pad- free saddle drawn on
2nd stage of denture design
Put support in
Side where bounded saddle - sue closest size of tooth
RHS - opposite side of abutment tooth
Mesial rest - free end saddle
4th corner of support - retromolar pad
Survey and find undercuts
Use occlusally approaching clasp for molar
Gingivally approaching clasp for premolar
3rd stage of denture design
Lower left 7 surveyed
Undercut on buccal side where rest was
Ring clasp
What is indirect retention
Situation
Imagine sticky food chewed by patient
If sticky tooth on mo6lar - pull denture upwards when apitent opens mouth
Clasp grip on denture as much as it can but nothing to clasp the denture form back
When do we use a sublingual bar
Anything in font of clasp axis - move downwards
Describe the saddle lifting in physics terms
Force to lift - effort
Effort needs to overcome resistance
Lifting source - effort
Keeping it in place- resistance
Physical weight of denture itsellf
Need to create resistance higher than normal effort hat is going to be encountered during this
Looking diagramatically in a denture
RPI on premolar
Connector to anterior tooth ith something resting on the anterior tooth
Upward forces caused by food
Transferred to downwards forces on that tooth
Equal and opposite force back
Rest would stay in place
If you career on lift the denture , eventually you’ll overcome force and resistance provided by the clasp
But denture much more difficult to remove because of the ret on the anterior tooth
Brought clasp right into the equation
Rest anteriorly is the fulcrum
Force is provided by sticky food -effort to displace the denture
Clasp is providing resistance to hat movement
Equation
Not expected to learn the equation
Effort has to overcome resent to lift the abr
Fitter the resistance form fulcrum the greater the effort to lift it
Denture design terms- further indirect retention is form clasp
More effective the indirect retention is
What are indirect retention
Denture design -draw clasp axis - clasp tips of two clasp closest form end of saddle
Dotted line drawn between clasp tips of those
Canine tooth- cingulum rest attached to minor retainer
2 clasps
Denture will rotate around imaginary line between those clasp tips
Define something as major clasp axis
Look where problem is
Free end saddle on RHS
Two clasp out of 3 closest o problem area
LR premolar -clasps
And clasp to LL molar
Opposite where indirect retention is going to be
What distance is required to choose a lingual bar between gingival margin and bottom of sulcus
When do we use a lingual plate
In this case
Covering gingival margins - instruction to keep it clean
Help spread load
Lots of denture teeth
Helping spread the laid
Indirect rentiton
In upper free end saddles what do we consider
Upper free end saddles
Some similar challenges
Bounded saddles
Teeth retained - nicely
Gravity and food sticky food
2 clasps
- effective
If patient loses backtooth and loses free end saddle denture - problem is very different
Nothing retaining the denture in the back and nothing to drop down
Soon as it drops down - drop out
Unretentive retainer
what are the strategies of free end saddles
Plate design
Wing connector or horse shoe
Plate connector SA
Plate and mucosa
Sitka denture to the roof of the mouth
Addition of post dam/pin dam
Suction underneath plate
Add to denture not dropping down
Create indirect retention
RHS - free end saddle on UL
Anything other side of that line act as indirect retention
What is a wax try in
First ot those
Wax try in
After recorded occlusion
Add denture teeth on
Only into wax
Replace them
Purpose of try in
Try out dentures with patient
Opportunity to see how they look and how teeth meet together
Alter things if need to
Wax try in
Shade
Mould
Size for the teeth
Out those into patient’s mouth and how well they fit in with patients own teeth
Up to patient to decide whether they are happy with that
What happens when you fit finished partial dentures
What is required when you fit finished partial dentures
Bite together
Same as it was
Appearance same as it was as try in
Patient walking away with them
Make sure patients happy
Honest opinion
What are the post insertion instructions advice to the patient to partial dentures
What are the post insertion instructions of dentures regarding cleaning, eating, wearing at night , pain
What do we do after giving the dentures to the patients
Review after one week
What do we do int he review appointment for dentures
How do we select patients
PATIENT - can manage good level of oral hygiene
Stable peiro status
No Denture with existing caries
Motivated- dentures are difficult
Abutment teeth -as strong enough to withstand extra forces
Thorough perio assessment
What is good practice of using dentures
Overarching guide toward denture design
Denture have adequate support
Gingival clearance where possible
Rigid - apart form a clasp tip
So all aspects of denture acts as one
