Class II Ag Matrices

Question 1

Who invented the matrix for Ag restos?

Answer 1

Dr. Tofflemire

Question 2

Qualities of good proximal restorations

Answer 2

• ideal contact position and dimension occluso-gingivally and bucco-llingually
• proper proximal contours
• proper establishment of embrasures
• flush margins

Question 3

Purpose of condensation

Answer 3

1. ensure adaptation of the Ag to the walls of the prep and the matrix
2. to produce a final restoration free of voids
3. to remove and eliminate excess mercury

Question 4

Why do we want to remove excess mercury?

Answer 4

Hg increases the rate of corrosion and increases risk of marginal fracture

Question 5

Poor condensation leads mainly to:

Answer 5

marginal leakage/recurrent decay

Question 6

height of Ag matrix?

Answer 6

1-2mm higher than the marginal ridge or tooth structure being replaced.

Question 7

Depth of Ag matrix?

Answer 7

0.5-1mm gingival to the gingival margin of the preparation

Question 8

What prevents excess Ag from flowing beyond the gingival margin of the preparation?

Answer 8

wedge

Question 9

How to recreate contour of the tooth with matrix band?

Answer 9

by using a ball burnisher against the adjacent tooth to replicate the convex surface of the proximal surface

Question 10

wedge functions!

Answer 10

1. separates teeth
2. stabilizes band (prevents movement)
3. prevents overhang

Question 11

What occurs if the wedge is positioned too occlusally?

Answer 11

• the band will not be kept tight against the tooth
• poor proximal contour
• poor contact
• OVERHANG

Question 12

What occurs if wedge is positioned too gingivally?

Answer 12

• will not keep band against tooth
• will not provide separation of teeth
• may damage soft tissue
• OVERCONTOURING OF RESTO
• GINGIVAL OVERHANG

Question 13

An ideally placed wedge accomplishes 3 main goals:

Answer 13

1. prevents overhang by keeping the band tight against the tooth
2. stabilizes the band
3. provides separation of the two teeth to compensate for the thickness of the band

Question 14

How to check for adequate wedging?

Answer 14

Check band and wedge placement with an explorer. If the band can be pushed from the tooth with the explorer, the wedge is either in the wrong position and/or not placed forcefully enough

Question 15

Two types of wedges

Answer 15

1. Anatomic:
   - wood (premier sycmore wedges)
   - plastic (flexiwedges)
2. Triangular:
   - Wizard wedges

Question 16

When choosing a wedge, choose the one that:

Answer 16

1. fits the embrasure completely

2. provides separation of teeth

Question 17

Which retainer do you use for lingual placement and which for vestibular placement?

Answer 17

CONTRAANGLE - lingual

STRAIGHT - vestibular

Question 18

What does the contraangle retainer accomodate for?

Answer 18

the incisal edges of anterior teeth (it goes over them)

Question 19

Which way should you orient the open portion of the retainer?

Answer 19

towards gingiva

Question 20

Role of outer knob

Answer 20

tightening the band against the screw

Question 21

Role of inner knob

Answer 21

adjust diameter of the band. Increase or decrease band size

Question 22

Types of matrix bands

Answer 22

1. conventional (flat) - must be contoured by operator
2. Pre-contoured
3. Dead soft or Ho Bands - matrix band has no memory

Question 23

Caution for precontoured bands:

Answer 23

take extra care removing the band since marginal ridges may break as the band is slid out from the contact

Question 24

What is the name of the system which is similar to a Tofflemire matrix system, but it is disposable/one-time-use?

Answer 24

Omni-matrix system. Developed for infection control, but not eco-friendly

Question 25

What are the possible consequences of having a band that extends more than 2mm occlusally?

Answer 25

• bending or moving band with condenser
• loss of visibility
• loss of access to cavity preparation