Amalgam/Composite Flashcards
What is amalgam composed of?
Mixture of mercury and metal alloy
alloy: Silver 40-70%
Tin 25-30%
Copper 2-30%
Zinc 0-2%
Alloy components and what they do for Amalgams
Silver : Increase expansion, Increase Strength of amalgam
Tin: Decrease expansion, decrease strength
Copper: Increase hardness
Zinc: Scavenger for oxides
What is the C- factor?
Configuration factor: it affects the developing stresses when cavity restored with composite
*It is the ratio of the bonded surfaces to the unbonded or free surfaces in a tooth prep.
High C- factor = greater potential for bond disruption.
5 Main ingredients of Dental Composite Resins
- Resin Matrix - holds all components together
- Dispersed inorganic filter
- Binding agent
- Polymerization initiators, activators…
- Color modifiers
3 components of bonding system
- Conditioner : (H3PO4 acid etchant) Organic acid
- Primer : hydrophilic resin (HEMA), Solvent
- Adhesive: Hydrophobic resin (Bis/GMA)
Total Etch / Selective Etch time
15 sec / 20 sec
Total Etch: 2 steps. Etch + Primer/Adhesive
Selective Etch: 1 step. Etch + Primer + Adhesive
Overall Composite process
a.) Rubber Dam
b.) acid etch enamel 20 sec. rinse thoroughly until etchant gone.
c.) Apply chlorhexidine 2% 60 sec.
d.) Dry with gentle air for 5 sec.
1.) Apply bonding agent, 2 layers, 20 sec
2.) Distribute with air 5 sec
3.) Light Cure 10 sec
4.) Dispense small amount Composite, layered fill technique
5.) Fill composite in incremental layers. Light cure each layer 20 sec.
6.) Carve last layer before curing. Remove flash, create flush margins. Cure 20 sec.
7.) Remove excess composite with carver.
Rubber dam thickness in lab, and sizes in lab
medium thickness: 0.008 inch
5 x 5 endo
6 x 6 operative
Creating Maxillary / Mandibular Arch on dental dam, measurements.
max: 1 inch from top, 4 mm rubber between holes
Mand: 2 inches from bottom
