external surface form, interim restoration Flashcards
what tray do you use to make an external surface form
Quadrant tray
What is used to create an external surface form
A vacuum-formed Matrix
How should the vacuum formed matrix be trimmed
4-5mm from the gingival margin
Mesial of 6 to mid of 1
Biologic requirements of interim restorations
Protect pulp Maintian periodontal health Occlusal compatibility Maintain tooth position Protect against fracture
Mech requirement of interim restoratiosn
Resists functional loads
Resist removal forces
Maintain interabutment alignment
Esthetic requirement of interim restorations
Easy to contour
Color compatibility
Color stability
Translucency
3 requirements for interim restorations
Easthetic
MEchanical
Biologic
What are the dental tubules after a crown prep
Open to the pulp so now sensitive
how to isolate the dentin from the oral environment
Use a provisional
What must be done to ensure that provisionals protect periodontal health
Magins must be done well
Correct contour
what happens to perio if too much contour
Inflammation and irritation
why does the provisional need to be in correct occlusion
Keep opposing tooth from supper erruption
How removable should a provisional be
Needs to be centered with a good fit
But also needs to be adjusted without fracture
what is the external surface form
The mold
What is the tissue surface form
The preped tooth
Types of external surface forms
Custom
PReformed
How is a custom external form made
use a polypropylane shell from a suck down on an impression
What are the types of preformed external surface forms
Resin: polycarb, Cellulose acetate
Metal: aluminum (plain), aluminum (anatomic), tin-silver, Nickel-chromium
Pros and cons of using a suckdown
Thin so good reproduction
Can also break
Pros and cons of putty for external form
Flexible
But can’t see how acrylic is forming
Why use wax for external form
If you’re cheap
How to chose a preformed polycarbonate provisional
measure space
Select crown
Try on patient
adapt
what is the finish margin for an aluminum preformed crown
Resin is the finish, not the metal
MEthods of Fabrication of Provisional restorations
Indirect
Direct
Indirect-Direct
Advantages of Direct provisional restorations
pateints preped teeth and gingival tissues directly provide the TSF
no intermediate steps of the indirect technique
when are direct provisional restorations convenient
When office laboratory facilties are inadequate for efficiently producing an indirect restoration
Disadvantage of Direct provisional
Potential tissue trauma from the polymerizing resin and inherently poorer marginal fit
Ideal properties of interim fixed restorations
Convenient handling: adequate owrking time, easy molding, rapid setting
Biocompatibility (non-toxic, non allergic)
Dimensional stability during solidification
Ease of contouring and polishing
Adequate strength and abrasion resistance
Good appearance
Good acceptability to patient: nonirritating, odorless
Ease of adding to or repairing
Chemical compatibility with interim luting agents
What must be done if External surface form is hard to remove
Might need to block out undercuts
Why pump the ESF 2mm
While it is setting at a rubber stage to preventing lockin in and overheating the teeth
Sequence of Polishing
Acytlic bur Moore disks Burlow wheels on the margins and axial Diamond on the occlusal Rubber points on occlusal if needed
Criteria for an interim restoration
Proximal contacts Occclusion Margins Axial Contours Finish
