DENTAL MATERIAL OSCE Flashcards
what is the composition of Amalgam?
POWDER: Ag (70%) Sn (25%) Cu (3%) Zn (1%) LIQUID: Hg (1%)
what is the composition of RMGI?
Fluro-alumino-silicate Glass + Barium Glass (powder) Potassium persulphate (powder) HEMA (liquid) Polyacrylic Acid (liquid) Tartaric Acid (liquid) Water (liquid) Photoinitiator (liquid)
what is the composition of Composite Resin?
FILLER = (quartz, silica, borosilicate) RESIN = BIS-GMA + urethane dimethacrylate resin monomer PHOTOINITIATOR = Camphorquinone LOW WEIGHT DIMETHACRYLATE = TEGDMA SILANE COUPLING AGENT
What is the composition of CaOH?
Calcium oxide and water
what is the composition of Vitapex?
CaOH
Iodoform
what is Amalgam typically used for?
Restoration of medium to large sized posterior cavities
what is RMGI typically used for?
Base or lining material
Restoration of deciduous teeth
Restoration of some permanent teeth
what is Composite typically used for?
Restoration of small —> large cavities anywhere in mouth (good aesthetics)
what is CaOH typically used for?
Lining material
Pulp cap
what is Vitapex typically used for?
To fill root canals after paediatric pulpectomy
what are the components of the BASE of CaOH?
- calcium hydroxide (50%)
- zinc oxide (10% - filler)
- N-ethyl toluene sulphonamide (40%)
- zinc stearate (1%)
what are the components of the CATALYST of CaOH?
- butylene glycol disalicylate (40%)
- calcium sulphate (30%)
- calcium tungstate (15%)
- titanium dioxide (13-14%)
what is Vitrebond?
RMGIC used as a lining
what is Riva (capsule)?
RMGIC used for restorations
what is Dycal? why is it used?
a setting CaOH liner
- normally used as a pulp cap
CaOH is an irritant, why is this good?
- High pH (kills microbes)
- Causes irritation to odontoblast layer, this results in tertiary dentine being made, this calcified bridge helps seal off the pulp
what is Ultracal?
a non-setting CaOH
what is ultra cal used for?
when performing a pulpotomy, ultracal can be used to temporarily fill canals
what is the composition of Conventional GIC?
Polyacrylic acid Tartaric acid Silicate glass Alumina Calcium fluoride (calciumfluoroaluminasilicate glass)
what are the steps of the setting reaction of GIC? Explain each in simple terms:
- Dissolution = H+ ions attack surface of glass particles
- Gelation = inefficient Ca cross links form to create calcium polyacrylate chains
- Hardening = aluminium polyacrylate chains are formed
why must the environment be kept dry during setting of GIC?
water causes the Al to leak out and weaken the bond
what are the steps of tri-curing in the RMGIC setting reaction?
- initial acid-base setting reaction SAME as conventional GIC
- the REDOX reaction begins (this causes setting in the dark)
- light activation causes free radical reaction to occur resulting in resin matrix formation
what is the setting reaction of ZOE?
An acid base reaction
- chelation reaction of zinc oxide with the eugenol to form a zinc eugenolate matrix which bonds to the unreacted ZnO particles
how strong is conventional ZOE?
Low strength = 20MPa
why is conventional ZOE not used as a cavity lining?
low compressive strength
how does resin modified ZOE differ from conventional ZOE?
- resins are added to the powder and liquid
- has an increased strength of 40MPa
how does ethoxybenzoic acid ZOE differ from conventional and resin modified ZOE?
higher strength of 60MPa and lower solubility
what is the gamma phase in the amalgam setting reaction?
Ag3Sn
what is the Gamma 1 phase in the amalgam setting reaction?
Ag2Hg3
what is the gamma 2 phase in the amalgam setting reaction?
Sn7Hg
what is the amalgam setting reaction?
Ag3Sn + Hg —> Ag3Sn + Ag2Hg3 + Sn7Hg
