Dental Waxes PDF

Dental Waxes Dr. Ahmad waadallah  Wax: Wax is defined as a substance that is solid at ambient temperature and when subjected to moderate temperature, become a low viscosity.  Composition of waxes Waxes are organic polymers consisting of hydrocarbons and their derivatives. These are comp...

Dental Waxes Dr. Ahmad waadallah  Wax: Wax is defined as a substance that is solid at ambient temperature and when subjected to moderate temperature, become a low viscosity.  Composition of waxes Waxes are organic polymers consisting of hydrocarbons and their derivatives. These are composed of mixtures of thermoplastic materials (softened by heating then hardened by cooling) The waxes that used in dentistry normally consist of two or more components which may be natural or synthetic waxes, resins, oils, fats and pigments.  ‫يجب أن‬-1 ‫يتوافق مع‬ ‫الحجم‬ ‫والشكل‬ ‫واملحيط‬ ‫الدقيق‬ ‫للجهاز‬ ‫املراد‬.‫تصنيعه‬ Requirements of dental waxes: ‫ يجب‬.2 ‫أن يكون‬ ‫لديه تدفق‬ 1. Must conform to the exact size and shape and contour ‫كافٍ عند‬ ‫ذوبانه‬ ‫إلعادة‬ of the appliance which is to be made. ‫إنتاج‬ ‫التفاصيل‬.‫الدقيقة‬ 2. Should have enough flow when melted to reproduce the ‫ ال‬.3 fine details. ‫ينبغي أن‬ ‫يحدث أي‬ ‫تغيير في‬ ‫األبعاد‬ 3. No dimensional change should takes place once it's ‫بمجرد‬.‫تشكيله‬ formed. ‫ يغلي‬.4 ‫الشمع‬ ‫دون أي‬ 4. Boiling out of the wax without any residue..‫بقايا‬ ‫ يمكن‬.5 5. Easily carved and smooth surface can be produce. ‫إنتاج‬ ‫سطح ناعم‬ ‫ونحته‬.‫بسهولة‬  Classification of Waxes: Natural waxes waxes Synthetic Synthetic waxes A- Origin: hydocarbons B- Chemical Composition: Ester C- Use and Application: 1- processing waxes 2- impression waxes 3- pattern waxes Natural Waxes: 1-Mineral waxes such as paraffin or microcrystalline wax. 2-Plant or ester waxes such as carnauba and candelilla. 3-Insect waxes such as beeswax. 4-Animal waxes such as spermaceti wax obtained from whale. Bees wax Paraffin Candelilla wax Types of Waxes in Dentistry: 1-Processing Waxes: A- Boxing and Utility waxes: Boxing and utility waxes are soft, pliable waxes used primarily in taking and pouring impressions. Boxing wax  Utility wax Wax for protecting the soft tissue from the periphery of the impression tray, to extend or post dam impression trays Beading wax used to make beading around the impression before pouring gypsum to protect the margins. B- Carding Wax: This wax with a high flow value at room temperature and is easily moldable without the need of heating. It is used for attaching parts.  C- Sticky Wax: It is used commonly to assemble metallic or resin pieces temporarily in position.  Orthodontic wax Block-out wax Tracing wax 2- Impression Waxes: A- Corrective Impression Waxes: A wax with high rate of flow at body temperature may be useful for taking corrective impression of the saddle areas. B- Bite -Registration Wax: Bite – registration wax is used for accurate articulation of certain models of opposing arches. 3-Pattern Waxes: A-Casting Waxes: Casting wax is used to form the wax pattern of the metallic framework of removable partial denture.  B- Inlay Waxes: Inlay waxes generally are used to fabricate wax pattern for crowns, inlays or bridges. C- Modelling or Base plate Wax: Base plate wax is relatively hard, and slightly brittle at room temperature but becomes soft, and pliable when heated. Applications of Dental Modelling Waxes: Construction of dentures:  Interocclusal records: Construction of orthodontic appliances:  Construction of extraoral prosthesis: Spacer in different uses:  Duplicating material: Block-out wax: Important Properties of Dental Waxes: 1-Melting Range: With complicated component, waxes have a melting range rather than a single, sharp melting temperature, because these waxes contain several types of molecules, each having a range of molecular weights. 2-Transition Temperature: At temperature above the melting point, the crystallites have melted and the wax is fully fluid. At temperature below the transition temperature, the wax is rigid and cannot easily be moulded. At temperature between the melting point and the transition temperature, the wax is partly fluid and partly solid, i.e. It is viscoelastic.  3- Flow: Flow is the change in shape under an applied force. Wax has a tendency to flow. It results from the slippage of wax molecules over each other.  4 -Stress Relief: In using dental wax, applying stress or pressure is undesirable. Waxes, like other thermoplastic tend to return to their original shape after manipulation. Stress – relief in wax is usually the result of adaptation at too low a temperature.  5-Thermal Expansion: Like other materials, waxes expand when subjected to arise in temperature, and contract as the temperature is decreased This fundamental property may be altered slightly when various waxes are blended, but the response to thermal changes cannot be reduced to negligible values.  6-Thermal Conductivity: The thermal conductivity of waxes is low which implies that these materials gain, and lose, heat very slowly.