Dental Materials

METALLURGICAL TERMS a. Cold Working. This is the process of changing the shape of a metal by rolling, pounding, bending, or twisting at normal room temperature. b. Strain Hardening. This occurs when a metal becomes stiffer and harder because of continued or repeated application of a load or force. At this point, no further slippage of the atoms of the metal can occur without fracture. c. Heat Softening Treatment (Annealing). This treatment is necessary in …

Casting of glass or ceramic A castable ceramic is prepared in a similar manner as metal cast preparation . Glass is heated to 1360 degrees & then cast. Phosphate bonded investments are used for this purpose .…

COMPOSITE RESINS Applications / Use Anterior restorations for aesthetics (class III, IV, V, cervical erosion abrasion lesions) Low-stress posterior restorations (small class I, II) Veneers Cores for cast restorations Cements for porcelain restorations Cements for acid-etched Maryland bridges Repair systems for composites or porcelains Polymerization--reaction of small molecules (monomers) into very large molecules (polymers) Cross-linkin…

Dental Implants Applications/Use   Single-tooth implants Abutments for bridges (freestanding, attached to natural teeth) Abutments for over dentures Terms Subperiosteal- below the periosteum -but above the bone (second most frequently used types) Intramucosal-within the mucosa Endosseous into the bone  (80%of all current types) Endodontics-through the root canal space and into the periapical bone Transosteal-through the bone Bone substitu…

CASTING DEFECTS Classification : 1) Distortion. 2) Surface roughness . 3) Porosity . 4)Incomplete casting . 5) Oxidation . 6) Sulfur contamination . Distortion It is usually due to the distortion of wax pattern. To avoid this : Manipulation of the wax at its softening temp Invest the pattern at the earliest . If storage is necessary store it in a refrigerator . Surface roughness May be due to : Air bubbles on the wax pattern . Cracks due t…