Operative Dentistry Flashcards
What determines cavity design?
- Structure and properties of dental tissues
- The disease - caries, periodontal disease, tooth surface loss
- Properties of restorative materials
Mention things you need to consider during cavity preparation and restoration
- Position of caries
- Extent of caries
- Shape of prepared cavity
- Restorative material
Position of Caries
- Pit & fissure (Susceptible areas)
- Approximal areas (Posterior & Anterior)
- Smooth surfaces (Gingival margins, erosion etc.)
- Roots (Those with periodontal disease)
When we may consider a restoration?
- Lesion has spread to dentine radiographically
- Lesion has caused pulpitis
- Lesion is unaesthetic
No attempt to remove healthy tissue should be made, unless…
- Material for restoration requires it
- Margins of cavity are in contact with another tooth surface
- Margins of cavity cross occlusal contact
Mention principles of cavity preparation
- Identify & remove carious enamel
- Remove enamel to identify extent of lesion at ADJ & smooth enamel margin
- Remove peripheral caries in dentine (From ADJ → Deeper regions)
- Remove deep caries over pulp (if applicable)
- Outline form modification (Shape)
- Internal design modification (internal line & point angles)
Mention ore detail on outline and internal design modifications of cavity prep (5,6)
- Remove unsupported enamel for proper etch adhesion.
- Smooth cavosurface margins and line angles.
- Avoid excessively acute line angles; ensure a smooth, rounded outline.
- Ensure no traces of previous restorative material remain unless doing a repair.
- Check for stress concentrators.
What CSMA Stands for?
Cavosurface Margin Angle
Things to consider when establishing final seal of cavity:
-Smooth margins present
-Appropriate CSMA
-No unsupported tooth tissue
-No stress concentrators
-Internal anatomy that allows adaptation of material
Explain 1st Principle – Access Caries
- Apply Dental dam
- Remove overlying enamel w/ high-speed bur
- Follow caries at ADJ
- Do NOT extend into non-carious areas
Explain 2nd Principle – Extent
- Caries spread at ADJ identifies cavity outline form
- Clear all caries at ADJ
- Check staining at ADJ
- Smooth Cavo-surface margins
- Examine adjacent contact for caries
- Avoid trauma to adjacent tooth
Why you should NEVER remove a restoration by
cutting around the edges?
Because you will increase the size of the cavity unnecessarily
Explain Principle 3 - Remove Dentinal Caries
- Softened ‘brown-stained’ tissue can stick to sharp probe
- Should all be removed using slow speed steel cutting bur
- Work from ADJ to Pulpal floor
- Do not probe uncavitated carious enamel
- Caution: pulpal exposure
How pulpal floor caries should be removed?
Large instrumentation to be used:
- Large round bur
- Large excavator ⛏️
- Chemo-Mechanical caries removal
Why you should use large instrument in removing pulpal floor caries?
Small burs and excavators will cut deeply more quickly – risk of pulp exposure
What is the aims of modification of cavity prep
To ensure appropriate:
- Enamel margins
- CSMA - Cavo-surface margin angle
- Occlusion
- Internal anatomy
- Dentine quality
What are the most commonly used restorative materials for direct plastic restorations?
Composite
Amalgam
What are the advantages of Composite?
- Aesthetics
- Involves greater conservation of tooth tissue (During prep)
- Existing support for remaining tooth tissue intact
- Adhesion/bonding mechanisms
- Command cure
- Low thermal conductivity
- Elimination of galvanism
Mention the advantages and disadvantages of Amalgam
- Does not directly bond to enamel/dentine → Requires specific cavity prep → Need to remove healthy tissue
- Does not support tooth
- A 2mm deep amalgam bulk required to prevent fracture
- May require sealed resin layer on cut dentine
- Strong under occlusal load
- Less moisture and technique sensitive
What is Non-adhesive & adhesive restoration cavity prep
Amalgam (Non-adhesive)
- Internal dimension > Cavity access
- Cavity margins should be caries free, accessible for cleaning & free of adjacent contact
Composite (Adhesive)
- Cavosurface angle adjusted to ⬆️ bonding area
- Ensures no unsupported enamel remains → as no undercuts
What is configuration factor?
Ratio of bonded to unbonded surfaces - an important concept for composite restorations
What high configuration factor means?
Bonding to 2 surfaces = High polymerisation contraction stress
What low configuration factor means?
Bonding to a single surface = Low polymerisation contraction stress
What is plasticity?
Is a property of a material to undergo a non-reversible change of shape in response to an applied force (polymerisation)
What is Deformation?
Is a change in shape due to an applied force (contraction)
Clinical procedure of Composite
- Etch
- Prime
- Bond
- Placement
- Characterisation
- Finish
