impression and cements Flashcards
Q: What are the advantages of conventional PVS impressions?
A: High accuracy, good for subgingival margins with proper retraction and hemostasis, less expensive than digital workflow.
Q: What are the disadvantages of PVS impressions?
A: Technique-sensitive, uncomfortable for patient (tray-risk of gag reflex), risk of distortion, keep track of consumables.
Q: What are the benefits of digital impressions?
A: Comfortable-less likely to gag dt tray placement, instant transfer to lab-reduce turn-over time, easy storage and retrieval of data, less error-prone, precise(with dry working field), immediate feedback of quality of impression.
Q: When is a digital impression less suitable?
A: When subgingival margins are not clearly exposed due to poor retraction or active bleeding.
Q: What should be considered when choosing between PVS and digital impressions?
A: Visibility of margin, clinician’s skill, available tech equipment, patient comfort, and tissue control.
Disadvantage of digital impression
High initial investment(long term more cost efficient) and training required. Unable to capture subgingival margins without proper exposure.
Zirconia and PFM: Can be cemented conventionally with?
RMGI/GIC OR using primer with MDP (adhesive phosphate monomers)
Lithium disilicate: Requires …. for cementation?
It has glass fillers, so need use…. as …
adhesive bonding. (has glass fillers so use silane as coupling agent)
what is Y-TZP?
yttria-stabilized tetragonal zirconia polycrystals [Y-TZP])
What forms when Zinc Oxide is mixed with Phosphoric Acid?
A: Zinc phosphate cement
What forms when Zinc Oxide is mixed with Eugenol?
A: Zinc eugenolate (Zinc oxide eugenol cement)
What forms when Zinc Oxide is mixed with Poly(acrylic acid)?
A: Zinc polycarboxylate cement
What forms when Fluoro-alumino-silicate glass is mixed with Poly(acrylic acid)?
A: Glass ionomer cement
Which two components make Zinc phosphate cement?
A: Zinc oxide and phosphoric acid
Which two components make Zinc oxide eugenol cement?
A: Zinc oxide and eugenol
Which two components make Zinc polycarboxylate cement?
A: Zinc oxide and poly(acrylic acid)
Which two components make Glass ionomer cement?
A: Fluoro-alumino-silicate glass and poly(acrylic acid)
What is the powder component of RMGIC?
A: Fluoroaluminosilicate glass powder
What are the liquid components of RMGIC?
A: Polyacrylic acid, HEMA (hydroxyethyl methacrylate), and tartaric acid
What is the role of tartaric acid in RMGIC?
A: Extends working time and shortens setting time
What are the setting reactions in RMGIC?
A: Acid-base reaction and resin polymerization
What are the typical base resins in Panavia SA (self-adhesive resin cement)?
A: Bis-GMA, UDMA, or TEGDMA
Bis-GMA (bisphenol A-glycidyl methacrylate), UDMA (urethane dimethacrylate), or TEGDMA (triethylene glycol dimethacrylate)
What are the inorganic fillers in Panavia SA?
A: Silica, zirconia, or barium glass particles - for strength and wear resistance
What is the purpose of silanized fillers in resin cements?
A: Act as coupling agents to bond filler to the resin matrix
