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matrices

MATRICES, RETAINERS AND WEDGES

  • matrices was introduced in the year 1871 by Dr. Louis jack.
  • Matrix is a device used to contour a restoration to simulate that of a tooth structure, which it is replacing.
  • Matrix is a device used during restorative procedures to hold the plastic restorative material with in the tooth while it is setting.
  • MATRICING
  • Is the procedure whereby a temporary wall is created opposite to axial walls, surrounding areas of the tooth structure that were lost during the cavity preparation.
  • IDEAL REQUIREMENTS OF A MATRIX
  • Matrix should be inserted easily
  • Should be sufficiently rigid to retain the contour given to it so that it can be transferred to the restoration.
  • Should not adhere or react with the restorative material
  • Should resist the condensation pressure
  • Ease of removal
  • Economical
  • OBJECTIVES
  • It must act as a temporary wall of resistance during introduction of the restorative material.
  • It should provide shape to the restoration.
  • Should confine the restoration with the acceptable physiological limits.
  • It must assist in isolating the gingiva and rubber dam during introduction of restorative material.
  • It must help in maintaining a dry operative field thereby preventing contamination of the restoration.
  • Correct location is in the gingival embrasure just beneath the contact area.
  • Wedge can be inserted buccally or lingually. It depends on cavity preparation and placement of the band. Location of the retainer dictates the direction of insertion.
  • Generally, wedge is inserted from the lingual side as this embrasure is larger in size. In lower arch as lingual wedge interferes with the tongue, it is placed from the buccal side. In upper arch it is placed from the palatal aspect.
  • Wedging should not be done from both the sides as it might leave large space just below the contact area leading to overhanging of the amalgam at that area.
  • Length of the wedge should be only ½” or 1.3cm so that it does not irritate the tongue or the cheek.
  • Care should be taken to ensure that the wedge is positioned apically in relation to the gingival cavity wall.
  • The gingival wedge should be tight enough to prevent overhanging of the restoration.

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