system used to hold the dental material and tooth together during the setting process

(a)  

Besides acting as a temporary wall, the matrix system provides the following features:

The two retainer systems used for class II restorations are the tofflemire retainer system and the

(a)  

• primarily positioned from the buccal surface of the tooth being restored.

• “universal retainer”

• is a mechanical device that holds a matrix band snugly in position

• designed for the placement of class II amalgam restorations and intermediate restorations.

• May use a contra-angle retainer if buccal surface needs a restoration

• A thin, flexible stainless steel material designed to adapt to the natural curve of the tooth

• Used for the placement of amalgam

The two designs of matrix band

(a)  

Components of a tofflemire and what they do

Is designed in such a way that when the ends of the band are brought together, the band forms a circle

(a)  

Describe the 2 circumferences of the matrix band

center of the matrix band should be (a)   in the proximal contact area

The thin, contoured matrix band is positioned first interproxi-mally, and then the wedge is firmly placed to close the cervical margin. The prongs of the tension ring are placed between the band and the wedge, thereby creating a solid closure of the cavity preparation.

(a)  

Advantages of using a retainerless matrix system:

is inserted into the lingual embrasure to hold the matrix band firmly against the gingival margin of the preparation

(a)  

Wedge selection criteria

Used to insert wedges

(a)  

Improper wedge and band placement can result in an ________ or in _______ of the final material

(a)  

Improper contouring can cause the patient to have

CRITERIA FOR PLACING THE POSTERIOR MATRIX RETAINER AND BAND

The clear plastic matrix, also referred to as the celluloid strip or (a)   strip, is used for a class III or IV restoration when the proximal wall of an anterior tooth is prepared.

The three purposes of the plastic matrix and wedge (anterior matrix system)

• An alternative to the use of a Tofflemire retainer and band

• This system has no retainer to hold the band in place

• Each band has a coil-like auto lock loop.

• The tightening wrench is inserted into the coil and is turned clockwise to tighten the band.