Document Type : Research Paper



Aims: To evaluate the effect of microwave disinfection on diametral tensile strength (DTS) of type III
and type IV dental stones. Materials and Methods: A total of 80 cylindrical specimens was prepared
with dimensions 40 mm in height and 20 mm in diameter. These specimens were divided into 4 main
groups: Geastone type III, Zeta type III, Micromod type IV and Silky Rock type IV. Twenty specimens
for each main group were divided into 10 specimens as control subgroup and 10 specimens representing
microwave irradiated subgroup. The microwave irradiation was performed in a household microwave
oven at 900 watts for 5 minutes. The DTS was conducted on a mechanical testing machine at a
cross head speed of 1.0 mm/minute. The data were statistically analyzed using Student's t–test, analysis
of variance and Duncan's Multiple Range test. Results: The microwave disinfection caused significant
increase in DTS (p < 0.05) for all types of dental stone, and dental stones type IV (Micromod and Silky
Rock) had significantly higher DTS (p < 0.05) than dental stones type III (Geastone and Zeta). Conclusion:
Microwave disinfection of gypsum cast cause significantly increase in diametral tensile strength
of type III and type IV dental stone.