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Amalgam is a metallic filling material composed from a mixture of mercury (from 43% to 54%) and a powdered alloy made mostly of silver, tin, zinc and copper, commonly called the amalgam alloy. [16] Amalgam does not adhere to tooth structure without the aid of cements or use of techniques which lock in the filling, using the same principles as a ...
Sometimes, a tooth is planned to be restored with an intracoronal restoration, but the decay or fracture is so extensive that a direct restoration, such as amalgam or composite, would compromise the structural integrity of the restored tooth or provide substandard opposition to occlusal (i.e., biting) forces. In such situations, an indirect ...
Creep or plastic deformation happens when subjected to intra-oral stresses such as chewing or grinding. Creep causes the amalgam to flow and protrudes from the margin of the cavity forming unsupported edges. "Ditch" is formed around the margins of the amalgam restoration after fracture due to amalgam creep at the occlusal margins.
The reconstructive ladder is the set of levels of increasingly complex management of wounds in reconstructive plastic surgery. [1] The surgeon should start on the lowest rung and move up until a suitable technique is reached.
The stress in the aligned fibrils will carry majority of the stress as the covalent bonds are significantly stronger than the van der Waals bonds. The plastic like behavior of polymers leads to a greater assumed plastic deformation zone in front of the crack tip altering the failure process. [6]
Resin-based glass ionomers have two setting reactions: an acid-base setting and a free-radical polymerisation. The free-radical polymerisation is the predominant mode of setting, as it occurs more rapidly than the acid-base mode. Only the material properly activated by light will be optimally cured. The presence of resin protects the cement ...
Long leg cast for tibial fracture. A long leg cast extends from the upper thigh to the toes, immobilizing the knee joint as well as the lower leg and ankle. It is typically used for injuries requiring stabilization across multiple joints, such as tibial or fibular fractures, severe knee injuries, or post-surgical recovery.
Two important quantities that are used to describe shape-memory effects are the strain recovery rate (R r) and strain fixity rate (R f). The strain recovery rate describes the ability of the material to memorize its permanent shape, while the strain fixity rate describes the ability of switching segments to fix the mechanical deformation.