Classification of Matrix Systems in Dentistry

Classification of Matrix Systems

• Classified according to involvement of the dental crown: Circumferential matrix or Sectional matrix system
• Circumferential matrix: Involves the mesial, distal, facial, and lingual surfaces simultaneously
• Sectional matrix: Involves only one of the proximal surfaces

Classification of Matrix Band

• Classified according to:
  • Thickness (in Micrometres)
  • Material (Metallic or Transparent)
  • Extension
  • Contour
• Metallic bands:
  • Don't allow passage of light
  • Made of Stainless steel
  • Varying thickness (~ ≤50 microns)
• Transparent bands:
  • Allow passage of light for adequate polymerization of composite increments
  • Made of polyester, cellulose acetate, or polyvinyl chloride (PVC)
  • Examples: SUPERMAT, SUPERLOCK, TENSIONING INSTRUMENT, ADAPT SUPERCAP MATRICES

Matrix Systems

• Circumferential matrix:
  • Involves the mesial, distal, facial, and lingual surfaces simultaneously
  • Used in all compound cavities, particularly those of three-surface type
  • Examples: IVORY MATRIX NO. 8
• Sectional matrix:
  • Involves only one of the proximal surfaces
  • Most widely used for restoration of Class II cavities using resin composite
  • Components: Rings, ring holder, bands, wedges, forceps

Sectional Matrix Systems

• Functions of the rings:
  • Aid in stabilizing the sectional matrix
  • Provide additional tooth separation while the composite is inserted
• Advantages:
  • Convenience
  • Improved visibility due to absence of a retainer
  • Ability to place the auto locks on both the buccal or lingual surface of the tooth

Application of Sectional Matrix System

• Steps:
  1. Matrix band placement
  2. Wedge placement
  3. Ring placement

Advantages of Sectional Matrix Systems

• The ring provides tooth separation for good interproximal contact
• Simplified matrix placement compared to circumferential band
• Better proximal contour due to shaped with multiple convexities
• Sectional matrix bands come in different thicknesses and extensions, suitable for most cases

Dental Wedges

• Definition: Pieces of wood, plastic, or elastic material introduced into the interproximal space to ensure correct restoration of the proximal surface
• Functions:
  • Stabilize the matrix band during application and condensation of the restorative material
  • Promote separation between the adjacent teeth
  • Aid in restoration of the adequate contour of the lost surface
  • Prevent extrusion of the restorative material in the gingival margin
  • Aid in retracting the rubber dam and the interdental gingival papilla

Classification of Dental Wedges

• Classified according to:
  • Material (Wooden, Plastic, Elastic)
  • Size

Wedge Placement

• The wedge should be inserted through the widest side of the embrasure
• Lingual or buccal side as long as the matrix is closely adapted to the cervical margin
• The wedges must enter under pressure and remain tight in position
• Errors to avoid:
  • WEDGE OCCLUSAL TO THE GINGIVAL MARGIN
  • WEDGE IS TOO LARGE
  • WEDGE IS TOO SMALL
  • WEDGE PLACED UPSIDE DOWN

Checking Proximal Contact

• Use floss in the gingival direction and pull laterally through the embrasure to avoid dislodging the restoration