Matrix System In Operative Dentistry Question And Answers

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:

1. Celluloid strips – For silicate cement
2. Cellphone strips – For resins
3. 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

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