Amalgam Cavity Principles

• assess:

  • amount/quality of remaining coronal tooth tissue
  • existing restoration - why failed? previous difficulties? how to overcome?
• what do we remove during tooth prep?

  • all existing restoration
  • caries as appropriate
• what cavity shape do we need to create?


  smooth flowing axial walls
• what burs do we use for cavity prep?

  • diamond burs - cavity shape
  • t.c or red composite - remove unsupported, weak, sharp enamel
• smooth outline form to facilitate a 90 degree amalgam margin angle butt joint with the filling
• embrasure walls in cavity prep?

  • must be straight
  • clear of contacts - to allow finishing and cleaning
  • use fine T.C bur and enamel hatchet to avoid notching adjacent tooth
• cervical margin in cavity prep?

  • clear of contact
  • removal cervical caries
  • round slow speed bur, finishing with cervical margin trimmer - mesial and distal
  • scale root face - aid matrix adaptation
• adjacent tooth?

  • unique access now to adjacent tooth
  • correct convex contour?
  • overhangs/rough area?
  • simple adjustments can be made if required
  • poor contact may clinically justify replacing adjacent filling
• opposing tooth?

  • over-erupted?
  • may compromise thickness/contour of new filling
  • might be adjusted to correct occlusal plane
  • no la - warn pt about post op sensitivity