The 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 the physiological integrity of the teeth with the adjacent hard and soft tissues
- restore patient comfort and satisfaction
Longevity of a restoration how long fo they last?
Success - ability for restoration to perform as expected
Durability? Success
Survival rate - measure of clinical performance
Length of a time a restoration survives
Failure - inability of restoration to meet desired outcome
Patient and clinical variabilities will affect the outcome of a restoration
Amalgam
Median survival rate 15 yrs
Causes of amalgam failure
- incorrect case selection
- cavity prep - inadequate retention
- poor matrix prep
- amalgam manipulation
- contamination
- failure to condense
- improper finishing and polishing
- post operative pain - inappropriate lining material
- micro leakage, ditching, creep !!! (Amalgam seals itself be fit and disadvantage)
- tarnish and corrosion
- faulty contacts
Composite
- low survival rate due to
polymerisation shrinkage / polymerisation stress - newer materials median survival 8yrs
- annual failure rate 2%
Some of the causes of composite failure
- incorrect case selection
- difficulty to obtain long term adhesion between the composite resin and the dentine, failure at the gingival margin is not uncommon
- failure to light cure composite in increments
- contamination of the material ; moisture control
- polymerisation shrinkage causing cares, fracture, sensitivity, marginal deficiency
Glass ionomer
Median survival 30-42 months in permanent teeth
Makes a good lining/base
Not strong enough to withstand heavy occlusal forces
Annual failure as a restorative material 7%
Causes of glass ionomer restoration failure
Result of poor handling of material at the time of placement or excessive occlusal loads
Implications of restorative failure
Time
Cost
Material choice
Technique
Remaining tooth structure
Factors affecting the success and failure of restorations
Patient factors
Operative factors
Material factors
Patient factors
- caries risk - OH, diet, regular GDP attender
- heavy occlusal forces; bruxism
- tooth to be restored
- cavity size / location
- pulpal health
- periodontal heath
- allergies
Allergies
- oral lichenoid reaction of oral mucosa against amalgam or gold alloys
- allergy to amalgam or gold alloys or sensitivity to HEMA in resin composites / fissure sealants
Operative factors
The correct choice of restorative dental material for the situation
Cavity design, retention, removal of unsupported enamel and weakened cusps
The optimal handling of that material
The use of exemplary clinical techniques in placement and finishing
Material factors
- compressive strength
- rigidity (modulus of elasticity)
- surface hardness and surface wear characteristics
- flexural strength
Material factors - micro leakage
Thermal expansion
Adhesion property
Resistance to fatigue
Solubility
Ditching and creep
Marginal degradation; ditching and creep
What are they a result of?
Ditching and creep are a result of slow deformation of amalgam places under constant load
(when the load is less than necessary to produce fracture, causing marginal breakdown)
Mostly seen where using amalgam with gamma 2 phase products
What is ditching?
Ditching / crevicing is breakage of a thin edge creating an irregular V shape crevice
What is creep?
Creep happens when the corrosive products leak and fill the gap between the tooth and the restoration
Amalgam is self sealing (creep corrosive product leaks and seals the margins, reducing micro leakage and secondary caries.
Creep happens under stress however which can result in the amalgam restoration failure
Assessment of restoration
FDI evaluation criteria
Aesthetic properties
- surface lustre
- staining
- surface margins
- colour match and translucency
- anatomical form
Functional properties
- fracture and retention
- marginal adaptation
- wear
- proximal anatomical form
- patients view
- postoperative hypersensitivity and tooth vitality
Biology
- recurrence of caries, erosion, abfraction
- tooth integrity
- periodontal response
- adjacent mucosa
- oral and general health
Ways in which restorations fail
Disease
- cares
- toothwear
- periodontal disease
- pulpal problems
- trauma
Technical failure
- fractured restoration / tooth
- marginal breakdown
- defective contours
- failure of retention
Clinically, how do you detect restoration failure?
Patient symptoms - pain / aestehtic concerns / disclouration / fracture
Visual and tactile inspection - caries / marginal breakdown / lost or fractured restoration / open contacts / overhangs
Transillumination
Radio graphic examination - caries / apical and periodontal status / overhangs
Occlusal examination - occlusal contact against the opposing structure / loss of anatomy
Reason for replacement - caries
Primary - at a new site on the tooth
Secondary / recurrent caries
- at the margin or under restoration
- caries left behind after initial restoration phase
Treatment options: repair or replace?
Repair the restoration is there is..
- no obvious spreading / gross caries that would structurally undermine the restoration or remaining tooth structure
- sufficient volumes of retained restoration remaining and it is strong enough to resist masticatory forces
- the possibility to bond or mechanically interlock the new restoration into the old restoration and tooth
- no potential aesthetic mismatches between the new and old material
