Par 2 - Maintenance & Repair Flashcards
What are the solutions to an RPD having the problem of loss of support?
- lab reline (preferred method)
- intraoral reline
- rebase
When making a lab reline, you make a ______ impression in base w/ appropriate material while holding rests securely in place & border molding.
open mouth
- make sure all rests are in place
What material would you use to reline mobile tissue?
Zinc-Oxide Eugenol
- just know that this is the only one for mobile tissue!
- all other materials are for firm tissue (VPS, Polysulfide rubber base, Polyether, Tissue conditioner)
What are the problems w/ intraoral reline materials?
- porosity
- color instability
- incomplete chemical bond, leakage
- viscosity can affect accuracy
- patient exposure to high levels of PMM
2 types of intraoral reline materials?
Methyl Methacrylates: bonds to acrylic; hardens & shrinks over time (2wks), can layer for better fit
Silicones: requires bonding agent; lasts longer w/ sealant (2yrs); cannot layer
T/F? When doing an intraoral reline, you want overextension.
FALSE.
What is the process of rebase?
Same process as reline, except the polished surface is removed & re-waxed to contour prior to processing.
- base & teeth are removed & re-waxed
What are the solutions for occlusal wear of the RPD?
- reprocess (rebase)
2. remake RPD
3 Methods for recreating master cast?
- alginate impression, pour cast, fit on framework to cast
- framework in mouth, make alginate “pick up” impression, framework remains in alginate & is poured up.
- dual impression: custom tray fabricated over retention lattice, impress w/ VPS, w/ framework in mouth, make alginate “pick up impression” over framework.
What type of stone do you use to pour up your alginate impression?
ONLY pour these up w/ type 3 stone (microstone)
- If you use die stone (type 4), acrylic may break later on in the process
What could cause loss of retention?
metal fatigue or clasp fracture results in the loss of retention for RPD
- RPD dislodges in an occlusal direction…
What are common indications for remake?
- framework distortion
- cast clasp fracture
- clasp assembly fracture
- loss of abutment teeth
T/F? Acrylic RPD is completely tissue supported.
TRUE.
What are the 3 restorative categories of acrylic RPDs?
- interim
- transitional
- treatment
- they all look the same, but function differently for the pt.
What is an indication for interim partial denture?
a definitive tx following w/i an expected time frame
- think of it as: “in the meantime…”
What is an indication for transitional partial denture?
extraction of hopeless teeth performed in stages
What is an indication for treatment partial denture?
a temporary RPD used during a healing phase; may or may not have teeth
OR post surgical application
- You can do these for pts who need a reline
- Start over with an RPD that is ALL acrylic, then reline with some tissue conditioner until the patient is healthy, then move on to the recommended RPD
What clasp would you use for an undercut in the interproximal area?
Ball clasp
__mm deep bead at the finish line bc it cant go any deeper (it’s not the vibrating line!)
.5mm
Advantages of flexible base RPDs?
- highly esthetic
- design versatility
- flexible
- “unbreakable”
- minimal/no tooth prep
- use w/ metal/MMA allergies
Disadvantages of flexible base RPDs?
- tissue supported
- difficult to adjust, repair, reline
- teeth are mechanically retained
- cost
Contraindications for flexible base RPDs?
- *** Distal Extension
- poor soft tissue quality
- loss of primary support anatomy (flat ridge)
- loss of restorative space
- periodontally compromised teeth
What is a common problem/caution with using alternative RPD materials (esp. tissue supported partials–like nylon or acrylic)
the lack of movement strips the tissue of the LINGUAL side of the teeth, and you create a periodontal problem for the patient —– so resurface this side
T/F? Esthetic clasps are highly esthetic, but also are highly flexible. They have an unpredictable design.
Both TRUE
