Presentation on theme: "Abdulaziz Al-Abdulwahed, BDS. Definition Something within or from which something else originates, develops, or takes form. Mold. Die. A material."— Presentation transcript:
Definition Something within or from which something else originates, develops, or takes form. Mold. Die. A material in which something is enclosed or embedded (as for protection or study). Merriam-Webster dictionary Your dictionary. com
The purpose Confine the amalgam so that adequate condensation forces can be applied. Allow reestablishment of contact with the adjacent tooth. Resist extrusion of the amalgam and the formation of an overhang. Provide for adequate contour of the proximal surface of the restoration. Establish an acceptable surface texture to the proximal surfaces, especially to the area that cannot be carved and burnished.
Qualities of a good matrix Rigidity. Establishment of proper anatomic contour. Restoration of correct proximal relation. Prevention of gingival access (marginal overhang). Convenient application. Ease of removal.
Types of Matrices Universal Matrix (Tofflemire): Indicated ideally for MOD, or lingual surface preparation. Can be placed in a facial or lingual in relation to the tooth. The Tofflemire retainer consists of different parts: Head. Slide. Rotating spindle. Set-screw. Used with most restoration materials.
Types of Matrices Precontoured bands. Precontoured Tofflemire band. Palodent. Limited application, due to very rounded contour. More suitable in distal of max. canines, and man. 1 st premolars. The contact area of the adjacent tooth is occasionally too close to allow placement of the band without making a dent on the contact area making it unusable.
Types of Matrices Automatrix. 4 different bands: Narrow regular, Wide regular, Medium regular, Medium thin. Indicated to be used with extensive CL II, involving two or more cusps. Auto-lock loop can be positioned either facially or lingualy. Difficult to establish a proper anatomic contour, since it wasn’t precontoured in the beginning.
Other types Omni-matrix: preassembled Tofflemire, intended for a one time use then disposal. Matrix strips: Dead soft, metal. Plastic strip. (CL lll, CL IV). Most matrices either comes in metal (steel), clear (plastic). Copper band matrix: used in complex amalgam restorations, rigid, recontourable, festooned.
Wedging Wedging is an integral, and a crucial part of the placement of the matrix. Used to stabilize the matrix in place, and to prevent the excess of amalgam (marginal overhang). Fundamental to retract the rubber dam in a gingival direction. Wedges can be: Wooden. Clear (plastic). Wizard wedge, triangular cross-section. Rounded wedges. Premier Sycamore wedges.