Clinical Amalgam Flashcards
What are the direct restorative materials?
Amalgam, composite resin, glass ionomer and RMGI
What are the indirect restorative materials?
Gold, other metals, ceramic
What are the contra-indications for amalgam?
Aesthetics, sensitivity to mercury, loss of tooth substance does not allow for retentive cavity, excessive removal of tooth substance would be required
What are the indications for amalgam use?
Direct restoration in moderate and large sized cavities in posterior teeth
What are the advantages of amalgam?
Durable, good long-term clinical performance, long lasting, resistance to surface corrosion, shorter placement time, radiopaque, economical
What are the disadvantages of amalgam?
Poor aesthetic qualities
Does not bond easily to tooth substance
Poor thermal diffusivity
Cavity preparation requires destruction of sound tissue
Marginal breakdown
Local sensitivity
Lichenoid lesions
What is the retention form of the cavity design?
Features that prevent the loss of the restoration in any direction
What is the resistance form of the cavity design?
Features that prevent the loss of the material due to distortion or fracture by masticatory forces
How is a resistance form made?
Cavity floor parallel to occlusal surface with sufficient depth of the cavity to give adequate mechanical strength
On what type of cavity would amalgam be acceptable for?
Moderate to large occlusal cavities
What are the cavity designs for interproximal caries
Self-retentive box preparation, proximo-occlusal preparation
What is a self-retentive box preparation?
Small undercuts made on buccal and lingual walls
What are the advantages of self-retentive box preparation?
Less tooth tissue removed, reduced amount of amalgam, sound tissue retained between proximal box and occlusal cavity
What are the disadvantages of self-retentive box preparation?
More technically demanding than proximo-occlusal preparation, further treatment of any pit and fissure caries may be required
What is a proximo-occlusal preparation?
Take out the fissure as well as interproximal caries
What are the advantages of proximo-occlusal preparation?
Retentive, also treats pit and fissure caries, less or no opportunities for future caries in pits and fissures
What are the disadvantages of proximo-occlusal preparation?
Destruction of tooth tissue, increased risk of weakening the tooth
What sort of initial retention factors can you include?
Grooves or dimples within cavity design, pin placement
How do you place a retentive pin?
Self-tapping screws, place into dentine, avoid pulp enamel and ADJ, pack amalgam around pin
What are the initial problems with pins?
Stress in tooth, cracking dentine, sensitivity of tooth due to temperature transference
What are the long-term problems with pins?
Filling can leak but will not fall out due to pin so secondary caries caused which can go deeper into tooth
How do you finish an amalgam cavity?
Ensure all caries is removed, smooth and round internal line angles, check and finish cavo-surface angles, smooth cavity margins