Principles of caries removal and prep Flashcards
What determines cavity design
Structure and properties of the dental tissues
The diseases (dental caries, periodontal disease, tooth surface loss)
Properties of restorative materials
When should a dentist intervene
When the lesion is cavitated
When the patient can’t access the lesion for prevention
When the lesion has entered the dentine radiographically
The lesion is unaesthetic
What is the structure of tertiary dentine and why is it important to consider with caries
Less organised, tubulestructure different which affects how restorative materials stick to it
What are the properties of dentine to consider when placing restorations
Type 1°/2°/3°
Intra/Inter/Peri tubular
Diameter
Density
Contents/Mineralization
What are the principles of preparation
-Caries removal
-Necessary finishing required for:
Maximising adhesion
Occlusal relationships
Ease of patient cleaning
Properties of the materials used
When might you consider removing healthy tooth tissue
The material used for the restoration requires it
The margins of the cavity cross an occlusal contact
Outline the principles of caries removal and cavity prep
Identify and remove carious enamel
Remove enamel to identify the maximal extent of the lesion at the amelodentinal junction & smooth the enamel margins
Progressively remove peripheral caries in dentine – from the ADJ first, then circumferentially deeper.
Only then remove deep caries over pulp
Outline form modification (cavo-surface margins)
-Enamel finishing
-Occlusion
-Requirements of the restorative material
Internal design modification
-Internal line and point angles
-Requirements of the restorative material
PA (point angle)
Junction between 3 surfaces
What is a Line angle
a junction between two surfaces
What are the factors of a final seal
Smooth margins
Appropriate CSMA
No unsupported tooth tissue
No stress concentrators
Internal anatomy that allows adaptation of material
Cavo-surface margin angle
the angle of tooth structure formed by the junction of a prepared (cut) wall and the external surface of the tooth
What are the beginning steps to dealing with caries
1st Principle – Access
Apply Dam
Remove overlying enamel with a high-speed bur to gain access to carious dentine
HIGH-SPEED ACCESS
Follow the caries at the ADJ
Do not extend into non-carious areas
What is the 2nd principle of caries removal
2nd Principle - Extent
Caries spread at ADJ determines outline form encloses extent of caries
Clear all caries at ADJ
Check Staining at ADJ
Smooth enamel Cavo-surface margins
Examine adjacent contact for caries
Avoid trauma to adjacent tooth
How should an existing restoration be removed
NEVER remove a restoration by cutting around the edges - you will increase the size of the cavity unnecessarily
Start from the centre of the restoration and cut towards the edge of the cavity
What does sticking of the probe on dentine indicate
Residual carious dentine which should be removed
How can we identify carious dentine
Brown stained or softened tissue when using sharp probe
When should stained tooth be left
When hard under the probe
What are the rules for removing residual carious dentine
Residual carious dentine must be removed first from the amelo-dentinal junction (ADJ) and last from the pulpal floor
How should caries on the pulpal floor be removed
Caries on the pulpal floor should be removed last using the largest instrument which will conveniently work in the cavity:
Large round bur
Large hand-held excavator
Chemo-mechanical caries removal
How do you manage pulp exposure
Pulp therapy such as pulp cap (CaOH)
What is the 4th principle
Modifications
How can the tooth be modified to yeild the best result for the restoration (i.e. smoothing enamel margins)
What is needed for amalgam to stick
REMOVAL OF EXCESS TOOTH
Features of the cavity which prevent the restoration being dislodged in any occlusal direction
Anatomical cavity design features: e.g. Undercuts, dovetail, key, isthmus
What cavity margins allow for maximum strength and minimum leakage
Bevel to align orientation with prisms for composite, but consider the best approach to achieve end cut prisms
Generally, the cavo-surface angle is between 90-120o for Amalgam: Butt joint
Above all, avoid inappropriate CSMA or fragile enamel
What does AMA, USE and CSMA stand for
AMA -Amalgam margin angle
USE - Prisms unsupported by underlying dentine
CSMA - Cavo-surface margin angle
Why might composite fracture within itself
Polymerisation strees, etch and bong is stronger than interstitial enamel strength. enamel surface wasnt properly prepared before composite was added
When do you decide on choice of material
After caries removal
Are caries all always removed
No not in all cases
