Failure of directly placed restorations Flashcards
Why do we restore teeth?
- To stop lesion progression and prevent its recurrences
- Restore occlusion and function
- Restore aesthetics
- Maintain physiological integrity of teeth with adjacent hard and soft tissues
- Restore patient comfort and satisfaction
What % of time do dentists spend replacing failed restorations?
65%
What can we say about the longevity of amalgam restorations?
one study - survival rate of 15 years
another - 22.5 years
annual failure rate of 3%
Name the causes of amalgam failure
Incorrect case selection
Cavity preparation has inadequate retention
Poor matrix preparation
Contamination
Failure to condense
Improper finishing and polishing procedures
Post-operative pain due to inappropriate lining material
Microleakage, ditching and creep
Tarnish and corrosion
Faulty contacts
What are the failure rates of early composite?
as high as 50% after 10 years
How has the survival rate of composites drastically improved with newer products?
median survival time of 8
years and annual failure rate of 2%
What are the causes of failure in composites?
Incorrect case selection
Difficulty to obtain long term adhesion between composite resin and dentine – failure at gingival
margin is not common
Failure to light cure in increments
Contamination of material via moisture control
Polymerisation shrinkage causing caries, fracture, sensitivity, marginal deficiency
What is the median survival time of glass ionomer?
30-42 months in permanent teeth
Annual failure rate when used alone as restorative material is estimated to be 7%
What is the main cause of GIC failure?
Case selection – failure of restoration is generally result of poor handling of material at time of placement or excessive occlusal loads
What are the patient factors affecting success and failure of restorations?
caries risk
Heavy occlusal loads (bruxism)
Tooth to be restored
Cavity size and location
Pulpal health
Periodontal health
Allergies (oral lichenoid reaction against amalgam or gold alloys, sensitivity to HEMA in resin composites/fissure sealants)
What are the operative factors affecting success and failure of restorations?
Correct choice of restorative material for situation
Cavity design, retention, removal of unsupported enamel and
weakened cusps
Optimum handling of that material
Use of exemplary clinical techniques in placement and finishing
What are the material factors affecting success and failure of restorations?
Compressive strength
Rigidity (modulus of elasticity)
Surface hardness and surface wear characteristics
Flexural strength
Thermal expansion
Adhesion property
Resistance to fatigue
Solubility
Ditching and creep
What is marginal degradation?
result of the slow deformation of the amalgam placed under constant load when the load is necessary to produce fracture, causing marginal breakdown
Where is marginal breakdown more common?
when using amalgam with gamma 2 phase products
What is ditching or crevicing?
breakage of a thin edge creating an irregular V shape crevice
What is creep?
when corrosive products leak and fill the gap between the tooth and restoration
What does the FDI evaluation criteria say about aesthetic properties?
Surface lustre
Staining
Surface margin
Colour match and translucency
Aesthetic anatomical form
What does the FDI evaluation criteria say about function properties?
Fracture and retention
Marginal adaptation
Wear
Proximal anatomical form
Patient’s view
Postoperative hypersensitivity and tooth vitality
What does the FDI evaluation criteria say about biology?
Recurrence of caries, erosion, abfraction
Tooth integrity
Periodontal response
Adjacent mucosa
Oral and general health
What are the ways in which the restoration will fail due to disease?
Caries
Tooth wear
Periodontal response
Pulpal problems
Trauma
What are the ways in which the restoration will fail due to technicalities?
Fractured restoration
Marginal breakdown
Tooth fracture
Defective contour
Failure of retention
What are the patient symptoms that denote restoration failure?
- Pain
- Aesthetic concern
- Discolouration
- Fracture
What is seen on visual and tactile inspection that denote failure?
- Caries
- Marginal breakdown
- Lost restoration
- Fractured restoration
- Excessive discolouration
- Open contacts
- overhangs
What can be seen on radiographic examination that denotes restoration failure?
- Caries
- Apical and periodontal status
- Overhangs
