Operative

Question 1

Carbonate-substituted hydroxyapatite (CHA) is

the main component of enamel and dentin

Question 2

How Does Fluoride Work?

Answer 2

• Remineralization of tooth structure
• Decreasing enamel solubility (lowering critical pH)
• Interfering with metabolic activity of cariogenic
bacteria

Question 3

Enamel (FA)= 4.5
• Enamel (CHA)= 5.5
• Dentin and Cementum= 6.2-6.7

Question 4

Streptococcus mutans enamel caries

Answer 4

– Gram positive cocci
– Glucosyltransferase (GTF) converts sucrose to glucans
and fructans, extracellular polysaccharides that help
stick it to tooth
– Acidogenic and aciduric—converts sucrose into lactic
acid and tolerates acid well
– Bacteriocins—kill off competing microbes
• Lactobacillus dentinal caries
• Actinomyces root caries

Question 5

Sealer/Desensitizer

Answer 5

Used for sensitivity
• Occludes dentinal tubules by
cross-linking tubular proteins
• GLUMA
– 5% glutaraldehyde
– 35% HEMA (hydroxyethyl
methacrylate)
– Water

Question 6

Liner

Answer 6

Used for direct or near pulp
exposures
• Provides a barrier to protect
dentin from residual reactants
of restoration and oral fluids
• Electrical insulation
• Thermal protection
• Pulpal treatment (formation of
tertiary dentin)
• CaOH or RMGI

Question 7

Base

Answer 7

Used for metal restorations
and when liner is used
• Thermal protection
(especially under amalgam
and gold)
• Distributes local stress
across all underlying dentin
• RMGI or GI cement

Question 8

Amalgam
– ≥2mm sealer
– 0.5-2mm base, sealer
– <0.5mm liner, base, sealer
• Composite
– ≥0.5mm bond
– <0.5mm liner, base, bond
• Gold or Ceramic
– ≥2mm cement
– 0.5-2mm cement (2mm thick)
– <0.5mm liner, base, cement

Question 9

Trituration

Answer 9

γ= unreacted silver-tin
• γ1= strong silver-mercury matrix
• γ2= weak tin-mercury

Normal mix= shiny, smooth
• Over-trituration= warm, wet, soft, sets too quickly
• Under-trituration= dry, dull, crumbly, sets too quickly

Question 10

Alloy Particles

Answer 10

Spherical
– Microspheres of
various sizes
– Easier to condense
– Stronger
– Sets faster

Admixed
– Mixture of irregular
and spherical pieces
– Requires more
condensation forces
– Better proximal
contacts

Question 11

Acute mercury toxicity

Answer 11

– Muscle weakness (hypotonia)
– Loss of hair (alopecia)
– Weight loss/GI disorders
– Exhaustion

Question 12

Enamel and dentin composition

Answer 12

Enamel: Mineral 88%, Water 10%, organic 2%

Dentin: Mineral 50%, Water 25%, organic 25%

Question 13

Etch:

Answer 13

30-40% phosphoric acid

Microporosity for enamel and widens the dentinal tubules in dentin.

Question 14

Primer

Answer 14

• HEMA (hydroxyethyl methacrylate)
– Monomer + solvent
– Can cause allergic contact dermatitis
• Infiltrates enamel prisms and dentinal
tubules
• Prevents collagen collapse

Question 15

Bond/Adhesive

Answer 15

• Bis-GMA (bisphenol A-glycidyl methacrylate)
• Chemically bonds to underlying primer AND
overlying composite resin through MMA
bonds

Question 16

Resin tags=

Answer 16

adhesive resins lock into the microporosities of etched enamel and intertubular dentin
• The key to adhesive dentistry is micromechanical bond

Question 17

Composite Resin

Answer 17

Resin matrix (Bis-GMA)
– Leaching of bisphenol A (BPA) can occur
through wear of composite or with uncured
resin
– Its potential to elicit adverse health effects
is negligible
• Filler particles (silica)
– Radiopaque
– Affect properties of the composite
• Coupling agent (silane)
– Promote adhesion between the two

Question 18

Larger fillers= more strength

Higher filler content= less water absorption

Question 19

Self-Cure

Light-Cure

Answer 19

– Two-paste system
– Benzoyl peroxide is
initiator
– Tertiary amine is
activator

– Single-paste system
– Camphorquinone is
photoinitiator
– 468 nm light needed
to initiate
polymerization