principles of caries removal and preparation Flashcards
what determines cavity design?
- structure and properties of the dental tissue
- the diseases (caries, periodontal disease, tooth surfae loss)
- properties of **restorative materials **
where can caries occur on the tooth?
4
- pit and fissures (occlusal)
- approximal (posterior / anterior)
- smooth surface
- root
when should you intervene and consider restoration with carious lesions?
5
- when lesion is cavitated
- when patient cannot access lesion
- when lesion is into dentine radiographically
- when lesion is causing pulpitis
- when lesion is unaesthetic
when should you remove healthy tooth tissue when cavity prepping?
3
- if the material for restoration requires it
- margins of the cavity are in contact with another tooth surface
- margins of the cavity cross an occlusal contact
what are the principles of cavity preparation?
- identify and remove carious enamel
- remove enamel to identify maximal extent of the lesion at the ADJ and smooth enamel margins
- progressively remove peripheral caries in dentine from the ADJ first then circumferencially
- remove deep caries over the pulp
- outline the cavo-surface margins (unsupported enamel, occlusion, requirements of material)
- internal design modificaitons (intermal line and point angles)
what are you looking for in the final cavity design?
- no traces of left over material if removing an existing restoration
- smooth external enamel line or point angles
- appropriate cavo-surface margin angles (CSMA)
- smooth internal dentinal line or point angles
- check for stress connectors
- no unsupported enamel
- internal anatomy allows adaptation of material
what is the first principle with a carious tooth?
**access the caries **
* apply dam
* remove overlying enamel
* follow caries at ADJ
what is the second principle with a carious tooth?
find the extent of caries
* clear all caries at ADJ
* check staining at ADJ
* smooth cavo-surface margins
* examine adjacent contact for caries
what is the third principle with a carious tooth?
**remove caries in tooth **
* detected as brown stain or softened tissue when using a sharp probe
* sticking of probe indicates residual cariosu dentine
* stain can be left if hard to probe
* stain must be removed from ADJ
what is the fourth principle with a carious tooth?
make necessary modifications
* decide what restorative material to use
* modify cavity prep
* enamel margins
* CSMA
* occlusion
* internal anatomy
* dentine quality
what instruments should be used when removing caries from the pulpal floor?
largest possible instruments
* large round bur
* **large hand-held excavator **
small instruments cut more deeply more quickly = risk of pulp exposure
how do you create retention for an amalgam restoration?
dentine undercuts required as is a non-adhesive restoration - healthy tooth tissue may need to be removed (weakens remaining tissue)
how do you create a cavity for adhesive restorations?
no undercuts or unsupoprted enamel, with cavosurface angles adjusted to increase bonding area
is a high or low configuration factor required for composite restations? why?
low configuration factor to reduce polymerisation stress - composite reduces in volume when set so tries to pull away from enamel and can break weak enamel
why is high polymerisation contraction shrinkage not ideal?
- material will shrink when set, away from dentine/enamel wall/floor and can fill with saliva or tubule fluid and secondary caries can occur
- can also pull away from the enamel and cause weak enamel to shrink
what are important things to remember when removing caries?
- you do not need to remove all caries (seal deep caries so don’t expose pulp)
- protect airway and pulp (dental dam)
- decide dental material after cavity is cut
- conserve tooth tissue and on adjacent teeth too
- seal vital dentine
