Reality Check #5

8/3/2019 Reality Check #5

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What is the difference????

Distal Extension Tooth Supported



1. How supported?2. Impressions used?3. Direct Retainer choices?4. Denture base material?

5. Indirect retention needed...is there an axis of rotation?

What Class could qualify as an apple or orange depending on the situation?



Know where fulcrum lines run!!!!!!!

If a partial is supported in part by soft tissue over residual ridge in an extension situation (CL I, II and IV?) then the partial WILL move in function and frameworkthat contact teeth will have the potential to place damaging forces on those teeth!!!!!

YOUR JOB WILL BE TO PREVENT OR AT LEAT MINIMIZE THOSE FORCES!!!!!!!

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Class I



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Class II mod 1



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Class III mod 1



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??? SOME SAY YES SOME SAY NO.

CLASS IVIF ROTATION POSSIBLE IT WILL DEPEND ON QUALITY

OF SOFT TISSUE OVER RESIDUAL REST AND THE EXTENT

OF THE EDENTULOUS SPAN.

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RESTS

Where and why would you place them?

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RESTS

Must

Optional…could be all, none or some combination based on the particular circumstance.

Make sure you know reasons for placing rests on the mesial of

terminal abutment on extension side(s).



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Could be incisal or cingulum



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Incisal or cingulum on a maxillary cuspid?What do you think?



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Placement depends on a lot of factors in these Cl IVs.Is it more an extension case or a tooth supported one?So do rests go on M or D of those bicuspids.Same for the molars…M or D of 1st or 2nd molars. Have to look at suchfactors as perio status, restorations and occlusion for starters.

NOT ALL CUT AND DRY!



GUIDE PLATES

Adjacent to edentulous areas to be restored.

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Not very effective



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Probably a li\le more effective than on mandibular arch aswider facial lingually but still not high incisal-gingivallyplus esthetics with metal showing an issue also.



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MAJOR CONNECTOR

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MANDIBULAR ARCH

WHY CAN’T I USE A LINGUAL BAR?

VS.



VS.

1. Enough room…10 mm2. Need bracing?3. Stabilize teeth?4. Future loss with addition to partial5. Indirect retention.



MAXILLARY ARCH

WHY CAN’T I USE AN A-P BAR?

VS.

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NOT AS CLEAR CUT AS ON THE MANDIBULAR ARCH!

1. What and where remaining teeth.2. Palate anatomy3. Tissue over ridges

4. Perio status of teeth.5. 5 year prognosis of remaining teeth6. What’s on opposing arch.7. Patient preferences if previous experiences.8. And others.



DENTURE BASE RETENTION

!What meets your needs?Remember that in extension situations you must be able to reline so mesh is alwaysindicated except in extremely rare situations. Look at lower left above!

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DIRECT RETAINERS

They keep the framework in place againstreasonable dislodging forces.



1. How are they classified?

2. Where should the tip be located.3. How deep into undercut are they placed?4. Once in place they should be what in relation to the tooth?



1. Supra and Infrabulge

2. As low on the tooth as possible to decrease torquing potentialbut not impinge on gingivae.

3. .01”” = ten one-thousand

4. PASSIVE



RECIPROCATION

WHERE? WHAT? WHY?



1. Rigid component placed at or above the survey line.2. Not in an undercut

3.

Opposite side of tooth from direct retainer.4. Ideally in contact with tooth while clasp tip is moving over survey line.5. Counter force place by clasp pushing against tooth when seating framework.6. Also provides bracing to resist movement of framework around a vertical axis.

Can be a reciprocating arm, lingual plate, minor connector or portion of guide plate.



NEVER CONTACT TOOTH BELOW SURVEY LINE

ORIT WOULD BECOME RETENTIVE



INDIRECT RETENTION

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WHY? WHAT? WHERE?



1. Resist movement of extension away from tissue.2. Located on opposite side of fulcrum line.3. Ideally as far forward from F. L. and at right angle.4. Ideally located on a flat tooth surface.5. Best is occlusal rest, cingulum rest, incisal rest and lastly plating.

* OBVIOUSLY IN CLASS I & II AND MAYBE IV*



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MINOR CONNECTOR



1. Connect other components to the major connector.2. Often indistinguishable from the components themselves.3. Just ensure all components connected to M.C.



Connecting occlusal rests to the lingual bar M.C.

None really distinguishable here!

Reality Check #5

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