Dental Materials

COMPOSITE RESINS Reaction Free radical polymerization Monomers + initiator. + accelerators-+ polymer molecules Initiators-start polymerization by decomposing and reacting with monomer Accelerators-speed up initiator decomposition Amines used  for accelerating self –curing  systems  Light  used for accelerating light-curing systems Retarders or inhibitors-prevent premature polymerization…

Applications/Use Load -bearing restorations for posterior  teeth  (class I, II) Pinned restorations Buildups or cores for cast restorations Retrograde canal filling material    (1) Alloy. An alloy is a solid mixture of two or more metals. It is possible to produce a material in which the desirable properties of each constituent are retained or even enhanced, while the less desirable properties are reduced or eliminated. (2)…

Investment Techniques  Single step investing technique: The investing procedure is carried out in one step either by brush technique or by vacuum technique. a). Brush technique: The accurate water-powder ratio is mixed under vacuum. A brush is then used to paint the wax pattern with mix then the casting ring is applied over the crucible former and the ring is filled under vibration until it is completely filled. b). vacuum technique: • The mix …

PHYSICAL PROPERTIES OF MATERIALS Definite and precise terms are used to describe the physical properties of dental materials. a. Hardness. Hardness is the measure of the resistance of a metal to indentation or scratching. It is an indication of the strength and wearability of an alloy or metal. b. Ductility. Ductility is the measure of the capacity of a metal to be stretched or drawn by a pulling or tensile force without fracturing. This property permits a…

ACRYLIC RESINS Use. Acrylic (unfilled) resins are used as temporary crown material. Temporary crowns are placed to protect the crown preparation and provide patient comfort during the time the permanent crown is being constructed…