What are the aims of restorations?
- to restore the integrity of the tooth surface
- restore function
- remove diseased tissue as necessary
- to restore appearance of tooth
What is the restorative cycle? (stairway/ladder)
Natural tooth - remove caries and place filling, then filling needs replaced creating a bigger cavity, then tooth breaks, crown, tooth aches, root canal treatment, eventually leading to extraction and replacement of indirect restoration
What is attrition?
- tooth to tooth mechanical forces leading to tooth surface loss
What is abrasion?
- loss of tooth substance by a foreign object e.g. toothbrushing
What is erosion?
- loss of tooth substance due to acid
- can be dietary or from stomach (extrinsic or intrinsic)
What is abfraction?
- loss of tooth structure due to flexural forces from the occlusal loading of the tooth, putting tensile stresses on the tooth, causing enamel rods to fracture and dislodge as the tooth flexes, causing v shaped notches
- more susceptible to abrasion and erosion
- common on canines and first premolars
Name some methods of cavity prep?
- traditionally
- micro-preparation
- chemomechanical caries removal (carisolv)
- sonic tooth preparation (vibration rather than rotation)
- air abrasion
- lasers
- ozone
- atraumatic restorative treatment
On a radiograph, how does occlusal caries present?
- radiolucency shows infected dentine
Must restore carious lesions into dentine on occlusal surfaces
What are the treatment options for occlusal caries?
- if in doubt, leave, wait, watch
- OHI
- fluoride treatment
- chlorhexidine as an antimicrobial
- fissure sealants
- sealant restoration
- conventional restoration
What are the stages to restoring an occlusal cavity?
- outline form: gain access to caries with high speed
- remove caries: along amelo-dentinal junction first, then caries overlying pulp
- apply lining in base of cavity as necessary
- etch, prime, bond
- restore with 2mm increments of composite
What technique is used for placing increments of composite?
Composite undergoes polymerisation shrinkage and should be placed using an oblique layering technique
- shrinks towards centre of material/restoration
- aim to touch only one wall of cavity to prevent pulling and reduce stress
What are the problems associated with polymerisation shrinkage?
- separation of material from cavity wall microleakage
- pulling on cusps - cracking of tooth
- separation from base of cavity causing a defect
- pain, secondary caries
What allows each increment of composite to bond to the next?
- oxygen inhibited layer - not set as well as rest of composite
- must polish final increment to remove this oxygen inhibited layer
What is the c-factor?
Configuration factor:
- demonstrates internal stress when using adhesive dental material that shrinks on setting
- number of bonded surfaces/unbonded surfaces
- highest c-factor is 5 (occlusal cavity)
