What are class II, III, and IV preparations? Which teeth do they involve? (Class II: proximal surfaces of molars and premolars; class III: proximal surfaces of incisors and canines; class IV: proximal surfaces of incisors and canines that include the incisal edge.) “ Matrices” is the plural term for “matrix.” There are different systems for posterior and anterior teeth.
Usually assembled before the start of restoration process. How does the posterior matrix system create a temporary wall during the restorative phase? Why is the universal retainer placed from the buccal position?
Extension bands are used for class II preparations when a universal band cannot reach the height of the tooth. What instrument would be needed to contour a band?
Top diagram: universal band. Middle diagram: extension band. The larger circumference is placed toward which surface? The smaller circumference is oriented toward which surface? Bands must be contoured to make proper contact with the adjacent teeth. What instrument is used to contour bands?
What is an embrasure? (A V-shaped space in a gingival orientation between the proximal surfaces of two adjoining teeth in contact.) Used to add pressure to the interproximal area during the restorative phase. Used to prevent overhangs. What is an overhang?
During transfer, ask the dentist what size wedge is appropriate. Wedges are transferred and applied with the use of cotton pliers or 110 pliers. How many wedges are used in an MOD/amalgam preparation? How many wedges are used in a DI/resin preparation?
Metal bands are not used because the resin/composite material can be scratched or marked by the stainless steel. No retainers are used. Why are clear strips used in resin/composite restorations?
Examples of clear matrix systems.
Anterior matrices can be contoured with the use of the end of a mouth mirror. Why would the matrix be placed before etching or bonding? Why would a wedge be used with a celluloid or Mylar strip?
Wedges are still used with this system. The tightening wrench and removing pliers are sterilized after each use. The band is removed and placed in the sharps container.
The blue-handled instrument is removing pliers. It has a cover to “catch” the cut piece of band for easy removal. The tightening wrench is the small “wand” in the box.
These are not commonly used. They are small, oval, and made of stainless steel. The tension ring is the “retainer.”
Used on posterior teeth only. Why would a sectional matrix be used instead of a universal retainer? How many rings would be used on a DO restoration?
A T-band is made of copper and adjusted to fit a primary tooth. A spot-welded band requires premeasurement of stainless-steel matrix material and hence more prep time. Why would a universal retainer not be used on primary teeth?
After placing the end of the band through the “wings” of the other end, secure the wings around the band. Why would this system not be used on permanent teeth?
Wedges are still used with T-band matrices.
A spot welder is used for the spot-welded bands.
This requires the use of a spot-welder. The process requires additional preparation time. The spot-welded band is form-fitted around the tooth. What size of pliers is generally used?