W1: Matrix Systems

Question 1

What types of matrix are there?

Answer 1

contoured and non contoured
avoid flimsy for post.

Question 2

Which wedge is not apart of system?

Answer 2

fender wedge, which is used for prep stage

Question 3

Order of sectional matrix

Answer 3

matrix
wedge
ring
use explorer to check gaps in gingival margin (impossible to remove excess material)

Question 4

If you detect gap in gingival margin what must you do?

Answer 4

don’t proceed. potential for secondary caries and periopocket

Question 5

MOD, what should you do?

Answer 5

use 2 matrix systems, complete mesial matrix, wedge and ring, repeat for distal

Question 6

where does ring orient?

Answer 6

outside of mouth

Question 7

What should we use for amalgams?

Answer 7

tofflemire

Question 8

tofflemire placement

Answer 8

parallel to arch

Question 9

slots of tofflemire should be facing which side?

Answer 9

always gingivally, facial side

Question 10

Metal band types

Answer 10

1. simple
2. gingival ext, goes into deep prox box

closing metal will make narrow and wider circumference, narrow part goes gingivally to follow crown which is narrower gingivally

Question 11

How do you orient the tofflemire band?

Answer 11

big up, small down

Question 12

Use of Tofflemires. Do they replace wedges?

Answer 12

Yes, can be used for MOD, but also MO or DO

Question 13

Automatrix is limited how so?

Answer 13

‘flat’

Question 14

Retainerless matrices limitation

Answer 14

can be bit big, need wedge

Question 15

When to use?

Answer 15

to recreate contour of proximal surfaces (cervical class V also, used to contour and adapt material more easily, prevent moisture)

Question 16

Direct placement of comp in comp veneers, which matrix do we use?

Answer 16

clear strip

Question 17

Why use matrix?

Answer 17

1. contour
2. proper filling, no gaps
3. no excess
4. contact
5. moisture prevention

Question 18

What is proper anatomic contour for tooth we are restoring?

Answer 18

consider embrasures on surfaces in 3D.

Question 19

Matrix must be placed beyond where? and why?

Answer 19

beyond cavity margin
- optimise bonding
- prevent ledges (AVOID LEDGES- would be really hard to remove, hard to clean, biofilm risk and result in secondary caries, or periodontal disease)

Question 20

Why are wedges used and where would they be placed?

Answer 20

• used to stabilise matrix in cervical area, though teflon can be used alternatively
• PLACE below contact area either Buccal or palatially (effects seal)
• some plastic wedges have concavities which lets it sit over papilla with low impact and helps it be inserted for better seal

Question 21

How do you create contour on tofflemire matrix which is flat?

Answer 21

‘burnishing.
use ball burnisher, identify from inside towards out where contact is and press few times to create contour.

if you do it outside it won’t be as precise.

Question 22

For proper contour you must….

Answer 22

ensure clearance of contact so matrix can fit

• if no clearance= no matrix can fit

Question 23

Flat vs precontoured matrix

Answer 23

flat= large space, food impaction, contact is too high, slight occlusal embrasure needs to be proper

to deflect food when masticating,

precontour= contact point more natural position

Question 24

Cons of V3 matrix

Answer 24

some matrix like V3 can make concavities. should be convex.

Question 25

Placement of wedge too high or wedge too large can.... + What is best position?

Answer 25

can deform matrix needs to be placed below contact, subgingivally. select right size.

Question 26

Adv of wooden vs plastic wedge

Answer 26

wooden= can adapt, if too big can make it thinner. plastic= not possible to adapt cross section resembles area under contact point. make sure base of triangle goes gingival

Question 27

how to place wooden wedge?

Answer 27

tip goes through. triangle fits IP area with BASE to gingival, top point of triangle to contact area

Question 28

We condense amalgam with pressure, we want to therefore...?

Answer 28

push wedge with pressure, and tighten matrix as much as possible.

Question 29

A matrix should be selected such that it ....

Answer 29

- covers. extends beyond the extent of the cavity - sits. can be engaged and stabilised. - bulges right place. maximum convexity of the matrix should be positioned against and in contact with the maximum convexity of the intact adjacent tooth to create an appropriate contact area - fits. The matrix should be able to be placed passively, unimpeded by contact with the adjacent tooth.

Question 30

material excess can lead to

Answer 30

Question 31

correct wedge placement in restorative phase?

Answer 31

- fender wedge: doesnt matter lingual/buccal lingual embrasure= slight bigger than buccal embrasure, place wedge like that it won't close properly. vv. place lingual embrasure= close ALWAYS from lingual or palatal embrasure, ensures no gingival space

Question 32

Why should we avoid a wide Contact?

Answer 32

material contact with soft tissue causing inflammation

Question 33

food impaction

Answer 33

happens when we don't place wedge far enough to pt where we feel tension/position.

Question 34

What is a solution to gaps in matrix?

Answer 34

teflon tape

Question 35

After resto

Answer 35

floss and check

Question 36

key takers

Answer 36

1. check for gingival gaps 2. master tofflemire and sectional V3 before trying others

Question 37

Why is creating a contact area between the restored tooth and adjacent tooth important?

Answer 37

- prevent food impaction in the area, - often being uncomfortable for patients and a common - cause for complaint. - also potentially increase the risk of further caries and periodontal disease,

Question 38

What is the difference between composite vs amalgam placement? (Oliver Baily 2001)

Answer 38

Amalgam is actively placed, in that it must be frmly packed and compacted into the cavity to form the restoration. Composite on the other hand is passively placed, in that there is limited force imparted and maintained during placement before curing (most commonly) with a light. It also shrinks when undergoing polymerisation. Tis explains the tendency of composites to perform less well than amalgam in terms of contact point creation and prevention of food impaction, even with so-called ‘packable composites’.

Question 39

Is it better to use composite or flowable when forming interproximal walls?

Answer 39

composite (Oliver Baily, 2021)

Question 40

A tooth is heavily broken down and you choose a tofflemire over a sectional matrix. What could be a potential con/adv if you use it?

Answer 40

tofflemire - adv: less overhangs bc stabilises matrix top down, esp inside out. cons: - contact area is too high and unnatural, often comes 'out' laterally forming unsupported marginal ridge ('overhang') -that can fracture, -food packs, uncomfy, - floss breaks. - AKA 'dead space'/ black triangles - can't fit wedge as well which can impact efficacy (OB, 2021)

Question 41

What are the cons/adv of sectional matrices?

Answer 41

- adv: sectional matrices have a surface concavity that tofflemire bands dont. Means we can form better contact area. - disadv: concavity/ indent can form which can lead to bacteria build up/ hard to clean, often not easy to identify. can lead to caries in proximal area.

Question 42

Comment on this placement of matrics:

Answer 42

Sectional matrices are good for maintaining contact area however if matrix is distorted it can form a concavity (don't want that, will be hard to clean and harbor bacteria causing caries) Fig. 3 a, b, c, d) Tooth restored using sectional matrix and separating ring. Very tight contact, with peripheral ledging and concavity at contact area and beyond. Concavity only evident when tooth removed

Question 43

The aim of a sectional matrix is to

Answer 43

a cleansable, anatomical restoration with a smooth convex surface, which is continuous with the remaining tooth structure and has a contact area at the level of the maximum convexity of the intact adjacent tooth

Question 44

which one is correct placement of matrix? A or B?

Answer 44

B is correct A the matrix is not in contact with neighbouring tooth. I.e: a) Matrix with insufcient occluso-cervical curvature not contacting adjacent tooth following appropriate wedging.

Question 45

comment on this matrix position (different views)

Answer 45

good contact area, but probs should position more downwards i.e: b, c) Matrix with increased occluso-cervical curvature resulting in acceptable positioning of contact (potentially slightly coronal). However, adaptation occlusal to the contact area is sub-optimal, potentially requiring increased fnishing. Repositioning the matrix more apically may address these issues. This may require adjustment of the matrix cervically C,D image is ideal

Question 46

Comment on D,E matrix position

Answer 46

- more curve up down so contact is good - adaptation of occlusal to contact is good con - bc it's more curved this could lead to distorted placement.

Question 47

comment

Answer 47

a) an eliott sep b & c) the wedge is not high enough to seal cervical area, you can see lil gap palatally d,e) better seal by placing 2 wedges fgh) teflon tape pack for seal ij) teflon wrapped around floss. technique for seal. pulle dsame time in opp directions to make a seal.

Question 48

What is adaptation and how do you optimise adaptation of matrices?

Answer 48

- adaptation: the transition from proximal wall to occlusal - trim it cervically... The mesio-distal matrix curvature and curvature occlusal to the contact area will also afect the marginal adaptation and therefore potential ledge formation in the resulting restoration, which will impact on the need for fnishing of the restoration (Fig. 4). Matrices may need to be modified; for example, by trimming them cervically, to optimise adaptation

Question 49

What is the teflon floss technique?

Answer 49

wrapping teflon around 2 floss and drawing it in from both sides of matrix. supposed seal, but unstable bc teflon lacks rigidity.

Question 50

If a matrix is not in contact with adjacent tooth what can you do?

Answer 50

choose diff matrix with more curvature up down.

Question 51

Why must thickness of matrix be considered?

Answer 51

no sep= movement. i.e. if these teeth aren’t separated before placement of the restoration. The teeth can be transitorily moved apart by virtue of the compressibility of their periodontal ligaments before placement, thus allowing the formation of a contact when the matrix is removed.7 This can be achieved by using wooden wedges, separating rings, or Elliott

Question 52

Why must matrix be stabilised coronally?

Answer 52

Wooden wedges can predictably provide lasting separation of 50 microns,7 which is sufficient to accommodate most metal matrices available, but some clear matrices are 75 microns thick, therefore separation with a wooden wedge alone would not be recommended

Question 53

What happens if you apply force to a matrix?

Answer 53

causes distortions - gaps leading to ledges or loss of contact area

Question 54

When placing matrix how can you prevent distortion?

Answer 54

clear contacts cervically and bucccopalatally

Question 55

What is stabilisation distortion and how can you prevent it?

Answer 55

- moving matrix - prevent by using had to stop as placing wedge (BELOW BASE OF CAVITY) to secure

Question 56

Comment

Answer 56

Question 57

Comment

Answer 57

wedge= prevent distortion/ moving problem sometimes, add ring= more distortion use wooden wedge i.e. "Anecdotally, rigid metal matrices lend themselves to a degree of self-stabilisation coronally, which facilitates their use without a separating ring in many situations. When a ring is not used, separation with a frmly placed wooden wedge or mechanical separator is required."