Dental Wax Casting Critical Questions PDF

# KEY TERMS - **Baseplate wax**: Dental wax provided in sheet form to establish the initial arch form in the construction of complete dentures. This product typically contains approximately 75% paraffin or cer wax, beeswax other waxes, and resins. - **Bite wax**: A wax form used to record the occlu...

# KEY TERMS - **Baseplate wax**: Dental wax provided in sheet form to establish the initial arch form in the construction of complete dentures. This product typically contains approximately 75% paraffin or cer wax, beeswax other waxes, and resins. - **Bite wax**: A wax form used to record the occlusal surfaces of teeth as an aid in establishing maxillomandibular relationships. - **Boxing wax**: A wax sheet form used as a border at the perimeter of an impression to provide an enclosed boundary for the base of the cast to be made from a poured material such as gypsum resin. - **Burnout**: Process of heating an invested mold to eliminate the embedded wax or plastic pattern. - **Corrective wax (dental impression wax)**: A thermoplastic wax that is used to make a type dental impression. - **Dental wax**: (1) A low-molecular-weight ester of fatty acids derived from natural or synthetic components, such as petroleum derivatives, that soften to a plastic state at a relatively low temperature. (2) A mixture of two or more waxes and additives used as an aid for the production of gypsum casts, production of nonmetallic denture bases, registering of jaw relations, and laboratory work. - **Direct wax technique**: A process whereby a wax pattern is prepared in the mouth directly on prepared teeth. - **Divesting**: Process of removing investment from a cast metal or hot-pressed ceramic. - **Elastic memory**: Tendency of a solid wax form to partially return to its original shape when stored at a higher temperature than that to which it was cooled. - **Flow**: Relative ability of wax to plastically deform when it is heated slightly above base temperature. - **Hygroscopic expansion**: Amount of setting expansion that occurs when a gypsum-bonded cast investment is immersed in water, which is usually heated to approximately 38 °C. (See Chapter 2 for more information on this process.) - **Indirect wax technique**: Procedure in which a wax pattern is prepared on a die. - **Inlay wax**: A specialized dental wax that can be applied to dies to form direct or indirect patterns for the lost-wax technique, which is used for the casting of metals or hot pressing ceramics. - **Refractory**: Capable of sustaining exposure to a high temperature without significant degradation. - **Sprue**: The mold channel through which molten metal or ceramic flows into a mold cavity. - **Sprued wax pattern**: A wax form consisting of the prosthesis pattern and the attached sprue network. - **Sticky Wax**: A type of dental wax that exhibits high adhesion to dry, clean surfaces when it is heated to a plastic condition. # CRITICAL QUESTIONS 1. **A wax pattern of an inlay made using the direct technique may result in a looser-fitting inlay than one made using the indirect technique. Why?** 2. **How can one best minimize potential distortion effects associated with elastic memory and temperature changes?** 3. **Under what conditions should medium and hard waxes be used?** 4. **Why should gypsum-bonded investment not be heated above 700 °C?** 5. **What are two measures that may be taken to minimize porosity in dental castings?** 6. **Why are premeasured packets of investments sometimes more cost-effective?** 7. **Why is the marginal fit of cast crowns on a prepared tooth essential to the long-term clinical success of metal prostheses?** 8. **What methods can be used to increase the abrasion resistance of master dies?** 9. **Why is the term "silver-plated die" technically incorrect?** 10. **What casting deficiencies may result when (1) the sprue former is too small in diameter, (2) the sprue former is attached without flaring to thinner areas, (3) the sprues are oriented toward thin areas of a wax pattern, or (4) the sprues are of inadequate length to position the wax pattern within 6 mm of the end of the invested ring?** 11. **How does nonuniform investment expansion occur? How can excessive longitudinal expansion be minimized?** 12. **How can the risk for porosity and incomplete castings be minimized?**