Compressive strength and surface roughness of die stone cast after repeated disinfection with sodium hypochlorite solution

Abstract EN

Background: The transmission of oral pathogen to impression and subsequently on to gypsum cast has been demonstrated, and dental stone cast have to be disinfected to prevent the transmission of infectous disease, this infection process may affect some physical or mechanical properties of the cast.

The aim of the study was to evaluate the compressive strength and surface roughness of type IV dental stone cast after repeated immertion in and sprying using (0.5%) sodium hypochlorite disinfectant solution.

Materials and methods: A total of (42 test blocks) were prepared and divided to (3) three groups (14each) (control spray and immersion) for the surface roughness test.

These were subdivided into (2) groups (7) each to be tested after (24 and 48 hours) the same distribution of the test block were followed for the compressive strength test.

For each test 1 / 3 of the test black immersed in the disinfectant solution for 30 minutes then allowed 24 hours for be each drying this was repeated 5 times before being tested, 1/3 of the specimens were sprayed with the disinfectant 5 times in an interval of 24 hours for bench drying the last 1 / 3 blokes were the control.

Results : Immersing or spraying with hypochlorite solution significantly decreased the compressive strength after 24 hours and increased after 48 hours.

As for the surface roughness the results showed that both spraying and immersion significantly increased the value of the roughness, with immersion as a higher value.

Spraying with (0.5%) sodium hypochlorite solution provide smoother dental stone casts surfaces and adequate compressive strength when allowed for (48 hours) compared to immersion group bench drying.

Conclusion : Dental stone casts disinfected by immersion method showed a higher surface roughness than those disinfected by spraying.