Ideal Class II preps Flashcards
Check gingival DEJ
often decaying
Hand tools and round bur
Only used in dentin, no other tools here (maybe spoon).
Outline form and initial depth
Outline: placing the cavity margins in the position that they will occupy in the final prep.
Initial depth - 0.2 to 0.8 mm pulpally from the DEJ usually 0.5mm
Resistance form
That shpae and placement of the cavity walls that best enable both the restoration and the tooth to withstand without fracture the forces on the long axis of the tooth
Formative
1 and 2 dentin
Defensive
Reparative dentin
Nutritive
supplies vital cells
Sensory
protective (pain response)
Functions of dentin/pulp complex
Formative, defensive, nutritive, sensory
Hydrodynamic theory
Micro-movements of tubule fluids. Osmolarity changes, thermal changes, desiccation, pressure changes, high-speed cutting
Changes here cause pain.
Irreversible pulpitis
hot tooth
Pulp pain is usually
sharp
Pulp status test
Cold hot test (pain or no pain, duration).
Electric pulp test
+, - (pain or no pain), value 1-80
Percussion test (perio ligament)
+ or - (pain/no pain)
Liners and bases
Protect pulp and minimize post-op sensitivity.
- act as thermal and chemical barrier
- electrical barrier
- mechanical barrier
- controls inflammation of the pulp
- controls fluid movement
Many of our restorative materials do not have a positive pulpal response
Liner
thin layers of material used to provide a barrier to protect dentin from residual reactants diffusing out of the restoration or from oral fluids that penetrate leaky tooth interfaces. Also have electrical insulation, generate some thermal protection, some formulas provide pulpal treatment
Solution liners
2-5microm - copal varnish, adhesives
Suspension liners
20-25 microm. Liner based on water and have suspended constituents instead of dissolved. CaOH2 (dycal)
Cement liners
200-1000 microm
Eugenol liners
ZOE and B&T
Dentin bonding systems/sealers
Optibond solo plus/gluma
Minimal caries
if RDS (remaining dental thickness) is greater than 2mm
Copal varnish
10 copal resin in acetone (2-5 microm). 1 layer = 55% selaed, 2 layers = 85% sealed.
Dentin bonding systems
liners with composities
Bases:
Thermal protection, supplement mechanical support for the restoration by distributing local stresses.
PDental cements mixed at higher powder/liquid ratios to increase
final compressive strength.
Moderate caries
Ideal prep does not remove all carious tissue. Extend access opening laterally until DEJ is not carious. Remove carious dentin.
Mixing technique - ZnPO4
Dispense 4-5 drops of liquid and some powder.
Divide powder into increments
Mix on a cool slab - allows for more powder to be added.
Avoid moisture (shortens set time)
Incorporate increments until you can pick up the mixture in your fingers without sticking.
Liners - CaOH
mix equal portions and apply to clean dry cavity prep.
Zinc oxide eugenol
Paste-paste system- equal proportions
Paste-liquid system - usually 2-3 drops of liquid per scoop of powder.
Advantages of glass ionomer
Adheres to tooth surface, fluoride release, proven record of retention, dimensionally stable, bio compatible.
GI reaction
condition dentin (remove smear layer. Acid matrix of mix dissolves periphery of glass, which releases ions. Divalent Ca ions chelate with acid polymer chains.
Over the next 24-72 hours, Al3 replace Ca2, more F released.
Acid side chains can also chelate with HA.
Extensive caries
Close to pulp - <0.5 mm RDT. Exposed pulp.
Pulp capping
near exposure RDT<0.5mm. Indirect pulp cap
Pulp exposure = direct pulp cap
Apply CaOH2 liner
CaOH2 liner
acid base rxn. Ca ions act to crosslink polyphenol groups. Insulator, high solubility, stimulates reparative dentin.
How CaOH2 works
release OH ions when ionoized in low concentration
Sedative restoration
for questionable pulp status or emergency treatment with limited time.
Reinforced Zoe, resin modified glass ionomer, GI.
Reinforced ZOE
Oil of clove acts as obtundent (pain dull), expands when set (seals). CANNOT USE UNDER COMPOSITE, inhibits polymerization.
Gross caries tooth asymptomatic
Extend access opening laterally until DEJ is non carious. Remove carious dentin. Leave small amount of caries over pulp rather than expose.
Deep caries asymptomatic
If RDT<0.5mm, no exposure. CaOH2 base
Deep caries questionable
If RDT<0.5mm or exposure. CaOH2, sedative fill. Seal is paramount, which is prompting some to use RMGI or GI.
