RESUMO
Objective: Previous studies have demonstrated that dental stone casts can be disinfected by replacing 10v% of required water with 5.25% sodium hypochlorite solution. This comparative study evaluated physical properties of dental stone models produced by replacing distilled water with sodium hypochlorite
Methods: In this in-vitro experimental study, a total of 45 dental stone models were produced in the following 3 groups. Group A included stone models fabricated by mixing 300g gypsum powder and 94 mm3 distilled water. Group B comprised of stone models produced by mixing 300 g gypsum powder and 94mm3 diluted 0.5% sodium hypochlorite solution
The third group [C] included specimens produced by mixing 300 g gypsum powder and 90 mm ' distilled water. Setting time, setting expansion and compressive strength of specimens were measured and compared. All tests were carried out according to ADA Specification No.25. Obtained results were entered SPSS software. ANOYA was applied for the comparison of 3 groups and Tukey's test was used for pair wise comparison
Results: Replacing distilled water with sodium hypochlorite caused a statistically significant reduction in setting time [mean reduction of 515 s] and increased the compressive strength of samples [mean increase of 4.06 MPa]. Setting time in group 2 specimens was shorter than that in group 3 samples but no statistically significant difference was noted in setting expansion of samples in the 3 groups
Conclusion: Replacement of distilled water with sodium hypochlorite had no adverse effect on setting time, setting expansion or compressive strength of dental stone casts and thus can be used as a suitable method for disinfection of casts in dental laboratories
RESUMO
Background: The purpose of this study was to generate discussion and communication among a group of general dentists in Tehran on their viewpoints regarding denture adhesives. Have they accepted denture adhesive as a material to enhance denture retention, stability and function? Materials and Methods: In the summer of 2007, a questionnaire was mailed to 300 general dentists who were assigned with a random systematic sampling method from general dentists in Tehran. The questions were arranged in two parts of evaluating knowledge and attitude. In evaluation of knowledge, dentists were classified into groups of good, moderate, weak and lack of knowledge. In evaluation of attitude, dentists were classified into positive, moderate and negative groups. (Evaluating attitude was carried out in good and moderate groups of knowledge.) Results: The study showed that 14%, 32% and 37% of the general dentists had respectively good, moderate and weak knowledge toward denture adhesive while 16.3% had no knowledge about this material. In evaluation of attitude through dentists with positive and moderate knowledge toward denture adhesive, 9.3%, 71.3% and 19.4% had respectively positive, moderate and negative attitude toward denture adhesive. The c2 test showed a significant statistical relation between situation of knowledge and experiences of dentists. Discussion: This study demonstrated that the rate of knowledge of these 300 general dentists in Tehran towards denture adhesives has not been in a good situation. It is believed that denture adhesive be able to enhance the fitness of a denture and provide psychological relief to the patient. Dentists agreed that education, not only for practitioners but also for patients, would raise the advantageous features and reduce the misuse of denture adhesive. Education of the topic "Denture adhesive" should be more concerned in dental universities.