Restorative - Week 10 PP

Question 1

Posterior Matrix Systems

Answer 1

-Universal retainer- also referred to as Tofflemire retainer
* A mechanical device that holds the matrix band snugly in position
* Positioned most commonly from the buccal surface of the tooth being restored

Question 2

Matrix Bands

Answer 2

Thin, flexible stainless steel material
The two designs most commonly used are:

• Universal band: Selected for the class II preparation
  when the proximal box is prepared to a minimum
  depth and width and the cusps are intact
• Extension band: Selected for the deeper class II
  preparation requiring gingival extensions

Question 3

Matrix Bands

Answer 3

The design of the matrix band is such that when the
ends of the band are brought together, the band will
form a circle
* One side of the circumference of the circle will be
smaller than the other side
The circumference guides you in placing the band:
* Smaller circumference: Gingival edge and is always
positioned toward the gingiva
* Larger circumference: Occlusal edge and is always
positioned facing toward the occlusal part of the tooth

Question 4

Contouring the Matrix Band

Answer 4

The center of the matrix band should be contoured
in the proximal contact area so the final restoration
will have proper contact with the adjacent tooth
* To contour the band, place on a paper pad. Using a
burnisher or end of the mirror handle, rub against the
inner surface of the band until the ends begin to curl

Question 5

Wedges

Answer 5

Class II restorations require a matrix band to act as an artificial wall for the tooth.
- The matrix band alone does not provide the
anatomic contour required interproximally
- A wedge is inserted into the lingual embrasure
to hold the matrix band firmly against the gingival
margin of the preparation

Question 6

Various Wedges

Answer 6

Wedges are made in various sizes, forms (triangular or round) and materials (wood or plastic)
-most commonly used type of wedge is the triangular or round wooden wedge

Question 7

Consideration for wedges include:

Answer 7

-wedge must be wide enough so that pressure is applied to apical and gingival walls of the preparation
-wedge presses the band aggainst the tooth and causes a slight separation of the teeth
-Wedge is slightly wider than the distance between the cervical portions of adjacent teeth

Question 8

Position the wedge

Answer 8

When positioning the wedge, #110 (howe) pliers or cotton pliers are the instrument of choice for inserting the wedge firmly into the embrasure

• for posterior restorations, the wedge will be positioned on the lingual side
• improper wedge and band placement can result in an overhang or in cupping

Question 9

Anterior Matrix Systems

Answer 9

-clear plastic matrix is used with anterioiur composite resin or glass ionomer materials (celluloid or mylar strip)

• used for a class 3 or 4 restoration when the proximal wall of an anterior tooth is missing
• no retainer is needed to hold the matrix in place, making this system and easier application

Question 10

Plastic matrix and wedge serve the following purpose during the restoration process:

Answer 10

-matrix is placed interproximally before the etching and bonding of the tooth to protect adjacent teeth from these materials
-after the placement of composite material, the matrix is pulled tightly around the tooth to help in reconstructing its natural contour

• clear plastic matrix allowxs for the curing light to penetrate the material, thereby completing the curing process

Question 11

Sectional Matrices

Answer 11

Posterior composite restorations require a different type of matrix system than is used with the universal band and retainer

• a thin, polished palodent-type matrix band and tension ring produce tight anatomic contact for composite resin materials in class 2 restorations

Question 12

Matrix Systems for primary teeth

Answer 12

-universal retainer and the matrix band do not fit primary molars properly because of the shape and size of these teeth

• t-band and spot-welded bands are two types of matrix systems designed to provide the correct width and depth needed for proper restoration of priimary molars

Question 13

T-Band (for Primary)

Answer 13

A copper band in the shape of a T
* When formed, the top portion of the T allows the
straight portion to adjust and fit the circumference of
the primary molar

Question 14

Preparing the T-band matrix involves:

Answer 14

• Bending the wings of the T-band to form a U-shaped trough
• Slipping the free end of the band loosely through the U formation
• Closing the wings, and pulling the free end to make a small loop of the band
• Holding the free end toward the facial surface, place the band loop on the tooth to be prepared