COMPARATIVE EVALUATION OF SURFACE HARDNESS OF TYPE IV GYPSUM PRODUCT USING THREE DIFFERENT DIE HARDENERS: AN IN – VITRO STUDY

Dr. Nimra Mehraj*, Dr. Samiksha Arora and Dr. Shobhit Garg

ABSTRACT

Statement of the problem: A die, commonly made of Type IV gypsum, should be dimensionally stable, hard and resistant to inadvertent abrasion caused during its fabrication. To increase the surface hardness, coating of die hardners has been recommended. But no conclusive data is available as some authors stated that the surface hardness increases while others were in view that it decreases or shows no effect on application die hardeners. Hence, this study was undertaken to evaluate and compare the surface hardness of Type IV gypsum products using different die hardeners. Materials & Method: A total of 60 samples, divided into four groups, were fabricated from the mould prepared by impression of the master die. Group I, II and III were treated with different types of die hardeners whereas, Group IV (control) was not treated with any type of die hardener. Micro Vickers hardness test was then conducted for the evaluation of surface hardness. Results: Statistically significant results (P<0.05) were found for surface hardness evaluation after the application of different die hardeners. Mean Surface hardness was highest with the control group followed by samples treated with mixture of vinyl and natural resins, Cyanoacrylate esters blended with acetone and least was seen with solution of phthalate resin. Conclusion: Die hardener coating applied on Type IV gypsum product decreases the surface hardness.

Keywords: Statement of the problem: A die, commonly made of Type IV gypsum, should be dimensionally stable, hard and resistant to inadvertent abrasion caused during its fabrication. To increase the surface hardness, coating of die hardners has been recommended. But