Restorative - Week 9 PP

Question 1

Matrix Systems

Answer 1

A matrix system provides a “temporary wall” for the restoration process in class II, III and IV preparations

to hold the filling material in place - or else it would spill out

Question 2

Posterior Matrix Systems - Universal retainer

Answer 2

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 3

Matrix Band

Answer 3

• Thin, flexible stainless steel material

The two designs most commonly used are:

• Universal band: Selectred 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 4

Design of Matrix Bands

Answer 4

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 5

Contouring the Matrix Band

Answer 5

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 6

Wedges

Answer 6

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 7

Types of Wedges

Answer 7

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 8

Considerations for wedges include:

Answer 8

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