Summary

This document provides an overview of soft lining materials used in dentistry. It details different types of soft liners, their properties, and applications. The document also includes information about different types of denture materials and their characteristics.

Full Transcript

Soft Lining material SOFT LINNING MATERIALS Soft liner TISSUE CONDITIONERS Tissue conditioners are soft elastomers used to treat an irritated mucosa supporting a denture. They are used only for short-term applications and should be replaced every 3 days. It has good...

Soft Lining material SOFT LINNING MATERIALS Soft liner TISSUE CONDITIONERS Tissue conditioners are soft elastomers used to treat an irritated mucosa supporting a denture. They are used only for short-term applications and should be replaced every 3 days. It has good effect on inhibition of the growth of oral bacterial flora and this should promote healing of inflamed tissues. Soft liner Tissue conditioner is composed of : Powder : Polymethyl methacrylate Liquid : Aromatic ester-ethyl alcohol mixture. Tissue conditioners are very soft, with no polymerization reaction, only it is physical. They become stiffer as a result of loss of alcohol. They are mixed at chairside, placed in the denture, and seated in the patient mouth Soft liner Properties that make tissue conditioners effective are: 1. Viscous behavior, which allows adaptation to the irritated denture-bearing mucosa over a period of several days. 2. Visco-elastic and elastic behavior which cushions the cyclic forces of mastication & spreading the load on the mucosa. Soft liner SOFT DENTURE LINER Permanent soft lining materials are resilient polymers used to replace the fitting surface of a hard plastic denture. Causes Patient cannot tolerate a hard fitting surface. To improve retention of the denture. Patients with irritation of the denture bearing mucosa, areas of sever undercuts, congenital or acquired defects of the palate. Desirable properties of soft liners are: 1. High bond strength to the denture base. 2. Dimensional stability of the liner during and after processing. 3. Permanent softness or resilience. 4. Low water sorption 5. Color stability. 6. Ease of processing. 7. Biocompatibilty Soft liner Types of Soft Liners Plasticized acrylic Silicone Room temperature vulcanizing (RTV) Heat cured Soft liner Acrylic soft liners The plasticized acrylics are consisting mainly of ethyl methacrylate. The monomer usually contains the plasticizer, which is a large phthalate ester. The monomer can be methyl methacrylate or butyl methacrylate Silicone soft liners  The silicones soft liners can be divided into two types: Room-temperature vulcanizing (RTV) Heat curing.  The resilience of silicones seems to be the ideal.  However, silicones have poor tear strength, no intrinsic adhesion to acrylic denture base. Soft liner 1. RTV silicones The RTV silicones' greatest drawback is their lack of adhesion, which is especially a problem in the attachment between acrylic denture base and silicone liner. Silicone liners support the growth of yeasts in the mouth. Nystatin (antifungal compound) reduces Candida albicans during active therapy.  The RTV silicones use an addition cross-linking system such as those used in impression rubbers.  Clinical disadvantages 1. Low degree of cross-linking. 2. Low serviceability. 3. Swelling and buckling during use. 4. Sensitivity to denture cleansers. 5. Rupture strength deteriorates with water. Soft liner 2. Heat-cured silicones eSiloxane methacrylate that can polymerize into the curing denture base and into the heat-cured addition silicone. Achieve a greater degree of cross-linking. Have much longer clinical lifetimes. DENTURE TEETH REQUIREMENTS 1) They should have good appearance, resembling natural teeth in shape, color and translucency. 2) There should be good attachment between the artificial teeth and the denture base. The artificial tooth and base materials should be compatible 3) The artificial teeth should be of low density in order that they do not increase the weight of the denture. Soft liner 4) The artificial teeth should be strong and tough 5) They should be hard enough … 6) They should allow grinding with a dental bur so that adjustments to the occlusion can be made by the dentist at the chair side. 1. ACRYLIC RESIN TEETH  Most denture teeth acrylic resin resemble denture base acrylic resin composition but with; More cross-linking agent added which are resistant to crazing. Stronger than the denture base acrylic resin. Have tooth-colored pigments rather than pink ones.  Acrylic denture teeth are “chemically” bonded to the acrylic denture base during processing of the denture. Soft liner 2. PORCELAIN TEETH Porcelain teeth are made by manufacturers in much the same shapes, sizes, and shades as acrylic teeth. Porcelain teeth are much harder and more stain resistant compared to acrylic teeth. Porcelain teeth are never used with diabetic patient Porcelain teeth are rarely used because; 1. They excessively wear the opposing teeth. 2. They cause trauma and bone loss in the supporting and opposing alveolar ridges. Mode of attachment Porcelain teeth are held in the denture by the mechanical undercuts or pins that are embedded in the back of the denture tooth. Soft liner Maxillo facial Prosthesis Soft liner Silicone rubber Soft liner

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