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33 Cards in this Set
- Front
- Back
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Ergonomics - Balanced Posture |
Feet flat on floor (avoid high stool with legs sloping downwards)
Thighs parallel with the floor or sloping slightly downward
Oral Cavity at or slightly above elbow height |
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Ergonomics - Balanced Posture (cont) |
- Place operative field in your midline (depth perception) - Elbows close to body - Shoulders parallel to the floor - Back and neck rather upright - Nose to oral cavity distance: |
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When working on maxillary, patient generally in _______________ position, but when working on mandibular arch ___________________ |
Supine
Raise chairback |
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What was used in the past to fill curved canals but did not seal resulting in a lot of endo failures? |
Silver points |
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What is used to clean and shape the canal? |
Endo file |
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T/F: For a vital pulp you use a pin retained core
For roots of irregular cross section or excess taper use ___________________. For round cross section and parallel sides, use _____________ |
True
Custom, dowel & Core
Prefabricated Dowel and Core |
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Core build up is used to retain _______________ . The post is used to retain _______________- |
Crown
Core |
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Assessment of Endodontic Therapy includes: |
- Adequately filled canals - Percussion/Palpation WNL (tooth must be asymptomatic) - Periodontal tissues WNL - Progressive healing of periapex (no PA lesions!) |
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Is restoring endo teeth construction or reconstruction? |
Reconstruction - Trying to build up from remains an image of the original |
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Would you consider reconstruction a chipped max canine with that needs to be used as an abutment for a bridge? |
Yes; frequently in function; need to make canine a stable abutment tooth |
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What's more important to periapical status of endodontically teet: Root canal or restoration of tooth?
What the study? |
Poor restorations resulted in more PA lesions than Poor endo (48.6 to 30.2)
Ray, Trope Study 1995 |
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Good restoration and good endo result in success rate of ___________________ |
95% |
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How many days does it take for bacteria to move through Gutta Percha? |
30 days; if you wait too long, need endo treatment again |
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Do posts reinforce endodontically treated teeth? Why or why not? When should they be used and what study? |
No, do not reinforce endo treated teeth (overused, can cause fracture) - placed in neutral axis
Should be used when remaining tooth structure is insufficient to support a restoration
Guzy GE and Nicholls JI |
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New philosophy:
Post holds the _______________ Core ______________________ Crown _________________- |
- Core
- Replaces lost coronal tooth structure
- Holds whole complex together |
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Disadv of cemented posts |
- Additional operative procedure - Additional removal of tooth structure - May complicate future endodontic treatment - May not provide adequate core retention in future |
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Pins and RCT Teeth should be limited to:
Why? |
Inaccessible canals (silver points), antirotational features for the core
Pins can cause dentinal crazing and fracture
*Only use 2-4 |
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Types of Posts |
Temporary (plastic, titanium, inexpensive alloy)
Prefabricated
Custom cast |
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Prefabricated posts |
Are round and tapered.
*Ex) Kerr, Filpost (more retention) |
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When should custom posts be used? How are they used? |
When canal is not round
Clean the root (eliminate undercuts, resin/wax used to get shape of canal. Core is then shaped with resin, tooth prepped to ideal dimensions |
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Post classification by shape: |
Tapered Parallel (root needs to be shaped properly for this) Parallel/tapered tip |
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Post Classification: Relationship to Dentin |
Passive - non-threaded, cemented (don't engage dentin
Active - Threaded (screw posts) & cemented (engage dentin, not cemented for retention) |
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Passive Post |
Less retentive, minimal stress during delivery, don't engage dentin |
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Active (__________) posts |
(Screw)
- More retention - Increased stress during delivery (when screwing in_ - Increased stress during function - Can lead to local dentin fracture or root fracture, especially true with thin roots |
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Stress distribution:
Greatest at: What angles produce high stress during loading As post length increases ______________ Cement layer results in ______________ |
Finishline and apex
Sharp
Stress decreases
Better stress distribution
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Tapered Stress distribution |
Wedge effect |
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Parallel - Stress distribution.
High stress at: |
Parallel - Better distribution, higher stress at apex, high stress if cement vent is not placed
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Threaded - Stress distribution
Highest stress during, concentrated at: |
Threaded - High stress during insertion and loading, better distribution if backed of 1/2 turn, stress concentration around threads |
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What is the purpose of cement? |
Stress distribution |
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Restoration Guidelines are dependent on: |
Tooth position Amount of Coronal tooth structure Tooth service (single restoration or abutment) Occlusion |
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If little tooth structure is missing; do you need a crown? |
No; fill excess root canal cavity with amalgam/composite, sufficient to restore tooth |
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Posterior teeth: |
Subjected to greater loads
Morphology more susceptible to fracture
Subjected to lateral loads
Biting forces create a wedge effect |
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How do you prevent posterior teeth from the wedge effect? |
Need cuspal coverage (crowns, onlays, etc) |
