Influence of water/powder ratio in the mineral and synthetic casts
Aim: To evaluate the influence of varying the water/powder ratio on the compressive strength of type IV mineral and synthetic casts. Methods: Four commercial brands of type IV mineral and synthetic casts were evaluated: Durone, Herostone, Fuji Rock, and Elite Rock. Ninety-six test samples were prepared from a silicone matrix, according to ADA’s standard no. 25. The samples were prepared according to the manufacturer’s recommendations with a normal water/powder ratio (n = 12) and with 20% extra water (n = 12), forming the control (A) and experimental (B) subgroups, respectively. Compressive strength tests were performed using a universal testing machine EMIC (DL 2000) with a load cell of 2,000 kgf/cm2. The obtained data were analyzed statistically using two-way ANOVA and Tukey’s test (α=5%). Results: The synthetic Elite Rock cast was statistically different from the one obtained when the portion of water indicated by the manufacturer was used; no significant differences were found in the remaining casts when the proportion of water was increased by 20%. Conclusions: the groups of synthetic and mineral casts differed and the water increase (20%) did not cause significant difference on the compressive strength of the materials.
2. Lindquist TJ; Stanford CM; Knox E. Influence of surface hardener on gypsum abrasion resistance and water sorption. J Prosthet Dent. 2003; 90: 441-6.
3. He LH; van Vuuren LJ; Planitz N, Swain MV. A micro-mechanical evaluation of the effects of die hardener on die stone. Dent Mater J. 2010; 29: 433-7.
4. Ragain JC; Grosko ML; Raj M; Ryan TN; Johnston WM. Detail reproduction, contact angles, and die hardness of elastomeric impression and gypsum die material combinations. Int J Prosthodont. 2000; 13: 214-20.
5. Sharma A, Shetty M, Hegde C, Shetty NS, Prasad DK. Comparative Evaluation of Dimensional Accuracy and Tensile Strength of a Type IV Gypsum Using Microwave and Air Drying Methods. J Indian Prosthodont Soc. 2013; 13: 525-30.
6. Gujjarlapudi MC, Reddy SV, Madineni PK, Ealla KK, Nunna VN, Manne SD. Comparative evaluation of few physical properties of epoxy resin, resin-modified gypsum and conventional type IV gypsum die materials: an in vitro study. J Contemp Dent Pract. 2012; 13: 48-54.
7. Valente VS, Zanetti AL, Feltrin PP, Inoue RT, de Moura CD, Pádua LE. Dimensional accuracy of stone casts obtained with multiple pours into the same mold. ISRN Dent. 2012; 2012:730674. doi: 10.5402/2012/730674.
8. Anusavice KJ. Phillips’ science of dental materials. 11th ed. Saint Louis: Elsevier; 2003.
9. Michalakis KX, Asar NV, Kapsampeli V, Magkavali-Trikka P, Pissiotis AL, Hirayama H. Delayed linear dimensional changes of five high strength gypsum products used for the fabrication of definitive casts. J Prosthet Dent. 2012; 108: 189-95.
10. Alsadi S, Combe E, Cheng YS. Properties of gypsum with the addition of gum Arabic and calcium hydroxide. J Prosthet Dent. 1996; 76: 530-4.
11. American National Standards/American Dental Association Specification No. 25. Dental gypsum products. New York: American National Standards Institute; 2000.
12. Schneider RL, Taylor TD. Compressive strength and surface hardness of type IV die stone when mixed with water substitutes. J Prosthet Dent. 1984; 52: 510-4.
13. Hiraguchi H, Nakagawa H, Wakashima M, Miyanaga K, Saigo M,Nishiyama M. Effects of disinfecting alginate impressions on the scratch hardness of stone models. Dent Mater J. 2006. 25: 172-6.
14. Hersek N, Canay S, Akça K, Ciftçi Y. Tensile strength of type IV dental stones dried in a microwave oven. J Prosthet Dent. 2002; 87: 499-502.
15. Craig GC, Powers JM. Restorative dental materials. 10th ed. Missouri: Mosby Year Book; 1997. p. 63-73.
16. Silva MA, Vitti RP, Consani S, Sinhoreti MA, Mesquita MF, Consani RL. Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven. J Appl Oral Sci. 2012; 20: 588-93.
17. Khan Z, Morris JC, von Fraunhofer JA. Effect of irreversible hydrocolloid impressions on surface hardness of dental stone. J Prosthet Dent. 1984; 52: 435-7.
18. Van Noort R. Introduction to dental materials. 4. ed. London: Mosby; 2013.
19. Schwedhelm ER, Lepe X. Fracture strength of type IV and type V die stone as a function of time. J Prosthet Dent. 1997; 78: 554-9.
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