## Matricing Important Notes

**1. Matrices**

## Matricing Short Essays

**Question 1. Define matrix. Discuss different types of matrices**

**(or)**

**Define Matrix. Describe matrices used for class 2 restoration.**

**(or)**

**Matrices used in operative dentistry**

**Answer:**

**Matrix Definition:**

- It is a device that is applied to a prepared tooth before the insertion of the restorative material to assist in the development of the appropriate axial tooth contours and to confine the restorative material excess

**Types Of Matrices:**

**1. Based on the mode of retention**

- With retainer- Tofflemire matrix
- Without retainer- Automattrix

**2. Based on the type of band**

- Metallic nontransparent matrices
- Non-metallic transparent matrices

**3. Based on the type of cavity**

**Matrix for class 1 cavity**- Double band tofflemeir

**Matrices for class 2 cavity preparation**- Single banded tofflemeir matrix
- Rigid material supported sectional matrix
- Ivory no. 8
- Ivory no 6
- Copper band matrix

**Matrices for class 3 cavities**- Mylar strip matrix
- S-shaped matrix

**Matrices for class 4 cavities**- Custom lingual matrix
- Mylar strip matrix

**Matrices for class 5 cavities**- Window matrix
- Cervical matrix

**Matrices For Class 2 Restoration:**

**1. Ivory Matrix No. 1:**

- For unilateral class 2

**Parts:**

- Claw
- Arms – 2 semicircle arms with pointed projections
- Tightening screw
- Band has a slightly projected part in the middle that is placed gingivally

**Placement:**

- Select and place the band
- Place the retainer
- Tighten the screw

**2. Ivory Matrix No. 8:**

- Band thin sheet of metal
- Circumference of it adjusted by screw

**Read And Learn More: Operative Dentistry Short And Long Essay Question And Answers**

- Used in unilateral/bilateral cases

**3. Tofflemire Universal Matrix Band Retainer:**

- Used in all types of tooth preparations

**Parts:**

- Head
- Slot
- Knurled nuts – Large and small

**Placement:**

- Open large Knurled nut
- Open a small knurled nut in the opposite direction
- Secure both ends of the band
- Place the band into a diagonal slot
- Tighten small knurled nut
- Place the retainer around the tooth
- Tighten large knurled nut

**4. Compound Supported Matrix:**

- Place the band around the tooth
- Secure it by sealing with an impression compound

**5. Auto-Matrix:**

- Preformed bands are available
- Adapt the matrix around the tooth
- Tighten the band with a locking device

**6. T-shaped matrix:**

- Made of brass, copper, or stainless steel
- The long arm of T surrounds the tooth and overlaps the short arm

**Question 2. Matrix Band and Retainer.**

**Answer:**

**Matrix Band and Retainer:**

**Retainer:**

- Holds the band in position and shape

**Band:**

- A piece of metal/polymeric material used to give support and form to the restoration while insertion and setting

**Materials:**

- Stainless steel
- Polyacetate
- Cellulose acetate
- Cellulose nitrate

**Dimensions:**

**Width –**¼ %” to 3/8″ for permanent- 1/8” to 5/16″ for deciduous

**Thickness –**0.0015″ to 0.002″

**Functions:**

- Confines the restoration
- Provide good contour
- Provide surface texture
- Prevent overhanging

**Requirement:**

- Rigid
- Adaptability
- Easy to use
- Easy to removal
- Non-irritant
- Sterilizable
- Inexpensive

**Question 3. Non-metallic matrix.**

**(or)**

**Matrices for tooth-colored materials**

**Answer:**

** Non-metallic matrix:**

- Used for tooth-colored restoration

**Types:**

- Celluloid strips – For silicate cement
- Cellphone strips – For resins
- Mylar strips – For composite and silicate

**Technique:**

- Obtain the desired length of the matrix
- Burnish it over the tooth
- Placement of wedge
- Restoring the tooth
- Hold the matrix till the initial setting

**Indications:**

- Class 3 and Class 4 restoration

**Advantage:**

- Simple to Use
- Economic

**Disadvantage:**

- Lack of stability

## Matricing Short Answers

**Question 1. Functions of the matrix.**

**Answer:**

**Functions of the matrix:**

- Functions Of Matrix Are
- Rigidity
- Establishment of proper anatomic contour
- Restoration of correct proximal contact relation
- Prevention of gingival excess
- Convenient application
- Ease of removal

**Question 2. Automatic.**

**Answer:**

**Automatic:**

- Bands are performed and disposable
- Height of band-3/16″-5/16″
- The thickness of band – 0.038-0.05 mm

**Steps:**

Adapt matrix around the tooth

↓

Tighten the band with a locking device

↓

Restore the tooth

↓

Cut the band with a plier

**Indications:**

- Tilted and partially erupted teeth
- Complex amalgam restoration

**Advantages:**

- Simple
- Convenient
- Good visibility

**Disadvantage:**

- Expensive

**Question 3. S-shaped matrix.**

**Answer:**

**S-shaped matrix:**

**Indications:**

- Restoring the distal part of the canine and premolar
- Class 2 slot restoration

**Advantages:**

- Good contour

**Disadvantage:**

- Cumbersome

**Technique:**

- Twist the band in S shape
- Place interproximal over facial
- The surface of the tooth and the lingual surface of the bicuspid

**Question 4. Copper Band.**

**Answer:**

** Copper Band:**

**Application:**

Select an appropriate copper band that surrounds the tooth

circumferentially 1-2 mm beyond the preparation margins

↓

Mount it over the softened stick of compound

↓

Fill it with restoration

↓

Place it over the tooth

**Indication –** Class 5 preparation

**Advantage –** Simple, Good contour

**Question 5. Sectional matrix system.**

**Answer:**

**Sectional matrix system**

- It consists of dead soft metal matrices available in various shapes, thicknesses, and sizes
- They are selected according to the tooth to be restored

**Indications:**

- For small to moderate class 2 cavities involving one or both proximal surfaces in posterior teeth
- For both amalgam and composite restorations

**Advantages:**

- Easy to use
- Good visibility
- Contact dimensions are adequate
- Gingival adaptation of restoration is good

**Disadvantages:**

- Expensive
- Matrix bands may become dented easily

## Matricing Viva Voce

- Matrix system consists of a matrix band, retainer, and wedges
- The thickness of a matrix band is 0.002 inches
- Matrix retainers are gadgets used to retain the matrix bands in position
- Tofflemire matrix band retainer is ideal to use when MOD preparation is done
- Automatrix is a retainer less matrix system with 4 types of bands used to fit all teeth
- Ideally the matrix band should be positioned 1mm apical to the gingival margin and 1-2 mm above the adjacent marginal ridge
- Tofflemire matrix is the universal matrix
- Compound-supported matrix is also called custom- made matrix or anatomical matrix
- T band matrix is performed T-shaped matrix without a retainer