Operative Dentistry: Matrices and Restorations

Matrices

• Custom-made matrices include T-shaped Matrix Band, S-shaped Matrix Band, and others
• T-shaped Matrix Band is indicated for patients who can't tolerate the matrix retainer and for Class II cavities in children
• Advantages of T-shaped Matrix Band include simplicity and being inexpensive and rapid
• Disadvantages of T-shaped Matrix Band include being flimsy in structure and not stable

S-shaped Matrix Band

• Indicated for Class 3 or Class 2 with Class V extension
• Compound material is used to hold the band in position in the facial, lingual, and gingival aspects

Types of Matrices for Compound Class I Restoration

• Occlusolingual preparation
• Class 1 with buccal or lingual extension
• Double banded Tofflemire matrix is used

The Wedged Metal Matrix

• Sectional matrix + wedge without the retainer
• Compound or gingival barrier can be used

The Soldered Metal Band

• A type of matrix band

Ligature Tied Band

• Also known as the Black's metal band matrices
• A piece of metal band is cut shorter and slightly less than the measurement of the neck of the tooth
• Gingival corners are turned up or a hole is punched near each end
• Dental floss silk is passed through one hole, along the length of the band, and back through the other hole

Wedges

• Devices used in rapid tooth separation, tooth preparation, and restoration
• Functions of wedges include:
  • Rapid separation of teeth
  • Preventing gingival overhang of restoration
  • Providing space to compensate for the thickness of the matrix band
  • Helping in stabilization of the retainer and matrix during restorative procedures
  • Providing close adaptability in the cervical portions of the proximal restorations
  • Helping in retracting and depressing the interproximal gingival area
  • Helping in depressing the rubber dam

Types of Wedges

• Plastic wedges
• Wooden wedges:
  • Triangular
  • Round

Wooden Wedges

• Made from soft wood like pine or hard wood like oak
• May be medicated
• Preferred due to:
  • Easy to trim
  • Adapt well
  • Absorb moisture and swell to provide adequate stabilization to the matrix band
  • Used along with metal matrices

Triangular Wooden Wedges

• Most commonly used
• Apex of the wedge lies in the gingival portion of the contact area
• Base lies in contact with the gingiva, helping in stabilization and retraction of the gingiva
• Used in tooth preparations with deep gingival margins

Round Wooden Wedges

• Not so commonly used
• Made from wooden tooth picks by trimming the apical portion
• Has a uniform shape
• Used in Class II tooth preparation

Plastic Wedges

• Have the disadvantage of being difficult to trim and adapt
• Diamond Wedge is a type of plastic wedge that solves many of the difficulties in using traditional, rigid wedges
• Diamond Wedge has a diamond-shaped cut-out in the tip, which collapses during insertion and springs open once through the embrasure, creating a tight seal and preventing the wedge from backing out
• Flexibility of the Diamond Wedge creates an excellent marginal adaptation, which eliminates the uncontrolled flow of excess composite and minimizes clean-up after the composite has been cured