Failure of restorations Flashcards
Why do we restore teeth?
Restore shape, anatomy, function and occlusion
Stop lesion progression and prevent recurrences
Aesthetics
Maintain physiological integrity of teeth with adjacent hard and soft tissues
Restore patient comfort and satisfaction
What is success?
The duration that the restoration will stay in fulfilling its objective - ability of the restoration to perform as expected.
What is failure?
Inability of the restoration to meet the desired outcome
What is success rate?
Used as a measure of clinical performance - length of time a restoration survives
What are the causes of amalgam failure?
Microleakage, creep, ditching Tarnishing Bad contacts Incorrect case selection Inadequate retention Poor matrix Amalgam manipulation Failure to condense Improper finishing and polishing Post op pain
What are the causes of composite failure?
Incorrect case selection Difficulty in adhesion to dentine Failure to light cure in increments Contamination Moisture control Shrinkage - marginal defects, secondary caries, fracture
What are the causes of GIC failure?
Poor handling
Excessive occlusal loads - makes excellent dentine replacement as lining but lacks physical properties needed to be used alone for posterior restorations.
Why is it bad that restorations fail?
Every time you replace a filling you remove more healthy tooth structure.
What are patient factors that influence treatment?
Caries risk - OHI, fluoride, diet, regular brushing
Bruxism/occlusal forces
Tooth to be restored
Cavity size and location - moisture control
Pulpal health
Periodontal health
Allergies - lichenoid reactions, amalgam, gold alloys or sensitivity to HEMA in resin/fissure sealants
How can sensitivity to amalgam be noticed?
In close proximity, can have a reticular, erosive, atrophic (erythmatous) or plaque like patch
What do you do if you have a patient sensitive to amalgam?
Remove amalgam and use different material and observe, lesion should disappear after two weeks, if no response refer to oral medicine.
What are operative factors that influence treatment?
Correct choice of material
Cavity design, retention, removal of unsupported enamel and weakened cusps
Optimal handling
Placement and finishing techniques
What are material factors that influence treatment?
Compressive strength Rigidity Surface hardness Wear characteristics Flexural strength
What do stronger materials resist more?
Deformation and fracture
Provide more equitable stress distribution
Stability
What does microleakage cause?
Secondary caries, minimum of 10um exists between restorations, not clinically perceivable but large enough to allow bacterial ingress.
What is creep?
A result of slow deformation placed under constant load, when load is less than necessary to cause fracture it causes marginal breakdown - mostly in gamma 2
What is ditching?
Breakage of a thin edge creating an irregular V shaped crevice
What do corrosion products do?
Leak and fill the gap between the tooth and restoration. Advantage - seals margins but is due to stress so can lead to failure
What does ditching cause?
Food packing and plaque which can increase risk of secondary caries
How do we assess restorations?
Aesthetics: surface lustre, staining, surface margin, colour, translucency, aesthetic form
Function: fracture, retention, marginal adaptation, wear, anatomical form, patients view, post operative sensitivity and vitality.
Biology: recurrence of caries, erosion, abfraction, tooth integrity, periodontal response, adjacent mucosa, oral and general health
How do restorations fail?
Marginal breakdown Fractures Trauma Caries Tooth wear Periodontal disease Pulpal problems Retention failure Defective contours Tooth fracture
How do we detect a failed restoration?
Patient symptoms Visual and tactile Transillumination Radiographs Occlusal examination
What is the main reason for replacing restorations?
Secondary caries
When do we repair?
No obvious spreading of caries into tooth that would undermine tooth structure
Sufficient volume of retained restoration remaining
Strong enough to resist masticatory forces
Possibility to bond old and new restoration to the tooth
No aesthetic mismatches
