Figure 4-26.Matrix retainers.
Figure 4-27.Amalgam matrix bands. A: Precontoured.
B: Junior (Pedodontic #15 with aprons). C: Wide #2 with
aprons. D: Junior #13 (Pedodontic). E: Universal #1.
Amalgam matrices are made of very thin flexible
stainless steel available in either roll form or in bands.
At times, the standard packaged matrix bands do not
provide the necessary length, width, or shape for a
particular cavity preparation. When this is the case, the
dentist can cut the metal matrix strips to form the
needed band. Bands used with the Tofflemire retainers
completely encircle the tooth. Matrix bands come in
assorted sizes and shapes, as shown in figure 4-27. The
most commonly used band is the Universal or Straight
#1 size. The Junior #13 is the smaller pedodontic
version of the #1 Universal. The Wide #2 and Junior
#15, (which have extensions known as aprons) are
used when additional length is needed for a preparation
extending below the gingiva. A dentist usually prefers
certain types of these bands over others. With practice,
you should become very proficient in having the
preferred band on the appropriate retainer.
When multiple surfaces of the tooth are removed
during the cavity preparation, a matrix is used to
approximate the original surface and hold the
restorative material in proper form and position until it
sets. The type of matrices used depends on the type of
restorative material placed. You will need to have the
right type of matrix available and assembled ready for
use during the procedure.
Amalgam matrices are made of very thin, flexible
stainless steel available in either roll form or bands.
The matrix band, retainer, and wedge are used in
combination to form a temporary mold while the
filling material is being packed.
The matrix is assembled and placed before the
amalgam is mixed. After the amalgam has been
packed, the matrix and wedge must be removed before
the final carving can be accomplished.
The most commonly used retainer is the universal
Its components are shown in
Figure 4-28.Components of the matrix retainer.