Fixed Pros Flashcards
Discuss characteristics of posts
Parallel:
- inc. retention cf tapered
- red. stress cf tapered (wedge effect focuses stress @ single point = #)
Serrated: 8x inc. retention cf smooth
Cement escape channel
- relieve pressure
- allow full seating
Rounded tip
- red. stress cf point/square (sharp corners create areas inc. stress)
- red. anti-rotational features of core
What type of post should never be used?
What is the best post?
Never use serrated tapered
Best: parallel, serrated w/ rounded tip
Downside of parallel sided post?
Difficult to provide sufficient width whole length of root
Guidelines for ideal post (length, diameter)
Length
- longer = more retention (better)
- > 50% canal length
- > crown height
- extend well below alveolar crest
- leave at least 4mm GP @ apex
Diameter
- wider = more flexural resistance but more tissue removal = inc. risk #
- wrought post: <1.25mm as strength in thin section
- at least 2mm remaining root tissue
How to choose post size?
Use measuring device against radiograph
Bottom of ‘ladders’ at apex (leaving 4mm GP)
Start w/ narrowest, move laterally until covers GP w/ minimal dentine removal
Ladders keep 2mm tooth tissue axially
Use to measure length of drill
Red should be min.
What is the Dahl concept?
Axial tooth movement when localised appliance/restorations are placed in supra-occlusion to disclude some teeth
Occlusion reestablishes full arch contacts over 6-24/12
This is intrusion (40%) + extrusion (60%)
Indications for Dahl concept
Req. inc. interocclusal space (extreme wear)
Inc. OVD when restoring (max 2mm w/o restorations)
Case severe ant. TSL
Restoring worn ant. teeth w/ comp to original dimensions (discludes post.)
Adv of Dahl concept
Min. removal of tooth tissue
Lost OVD can be restored
Min. facial ageing by restoring facial height
Safety
On average how much intrusion + extrusion take place w/ Dahl?
Intrusion: 1.05mm
Extrusion: 1.47mm
Concerns w/ Dahl concept
Assessing inc. OVD is tolerable; splint before
Assessing eruptive potential; silicone inter-occlusal record before
Provide stable contacts along long axis
Avoid O trauma
What are diagnostic wax ups?
Waxing of intended restoration contours on dental casts for evaluation + planning restorations
Indications for wax ups
Wear Missing Implant planning Diastemas Space planning
Why are wax ups useful?
Diagnostic procedure to determine clinical + lab procedures
Ensures predictability
Tool for Dx/Tx
Indicates need for ortho or pre-prosthetic surgery
Informed consent
Trial of potential outcome
Aid pt discussion
