The effect of repeated immersion of gypsum cast in sodium hypochlorite and glutaraldehyde on its physical properties: An in vitro study

Abstract

Background:One method used to disinfect a dental cast is immersion in a disinfecting solution. Repeated immersion of a cast in disinfectant may affect its physical properties.Purpose:The purpose of this study was to evaluate the changes in dimensional accuracy and hardness of the dental casts as a result of repeated disinfection in 0.525% sodium hypochlorite and 2% glutaraldehyde solutions.Materials and Methods:Sixty specimens were made of type III dental stone. Twenty specimens were immersed in slurry, a supernatant solution of calcium sulfate in distilled water (control casts), 20 specimens in 0.525% sodium hypochlorite, and 20 specimens in 2% glutaraldehyde solutions for 30 min and air dried for 24 h. This process was repeated for 7 times for testing. Linear dimensional change and hardness were determined according to American National Standards Institute/American Dental Association (ANSI/ADA) standards. The data were analyzed using two-way analysis of variance.Results:For specimens prepared with type III stones, treatment was by immersion in slurry (group I – control casts), and by immersion in 0.525% sodium hypochlorite (group II – test group 1) and in 2% glutaraldehyde solution (group III – test group 2). The specimens treated with sodium hypochlorite and glutaraldehyde showed more linear dimensional change compared to the specimens treated in slurry. However, the difference between test casts and control casts was significant. But the difference between the two test groups was not significant. Both the test groups showed decrease in hardness of the specimens compared to that specimens in control group. But the difference between two test groups was not significant in hardness. However,the values remained close to ANSI/ADA standards.Conclusion:The results demonstrated that repeated immersion of type III dental stone specimens in slurry with distilled water, 0.525% sodium hypochlorite and 2% glutaraldehyde, along with drying in air, caused a significant increase in linear dimension and a significant decrease in hardness.

Effect of Different Energy Levels of Microwave on Disinfection of Dental Stone Casts

“…28 In the current study, the disinfection was achieved with regards to P. aeruginosa and S. aureus with the recommended and applied concentration of 1:10 dilution of commercially available NaOCl (approximately 0.06%), similar to that used previously. 29 Disinfection regarding C. albicans was seen at a lower concentration of 0.03%. The higher persistency of P. aeruginosa to microwave disinfection, similar to that seen in previous literature, 15 was also seen in the chemical disinfection group.…”

Effect of Incorporation of Disinfectants on Surface Hardness and Dimensional Accuracy of Die Stone: An in vitro Study

“…9 All disinfectants have their pros and cons. For example, glutaraldehyde 10 has been proved to be sporicidal, viricidal, fungicidal, and bactericidal. However, it should not be used as a spray disinfectant as the fumes are toxic.…”

Efficacy of Microwave Disinfection on Moist and Dry Dental Stone Casts with Different Irradiation Times

“…The most used disinfection processes are chemical methods including immersion of the contaminated objects in sodium hypochlorite (5,6). However, the efficacy of this method on microorganisms has not been able to fulfill all disinfection requirements (4,7,8) and microbial transmission requires blockage by a practical, easy and effective disinfection or sterilization procedures.…”