Evaluation of the Reusability of Dental Stone Powder After Crushing and Rehydration: An In Vitro Mechanical Study

Abstract

Aim: This study aimed to evaluate the effect of recycling type III dental stone powder through crushing and rehydration on surface hardness, compressive strength, surface roughness, and setting time compared with conventional dental stone.

Materials and Methods: Eighty specimens of type III dental stone were fabricated and divided according to the performed tests into control and recycled groups. Before recycling, the previously set dental stone specimens were disinfected using 0.525% sodium hypochlorite solution, then crushed, dried at 100°C for one hour, and remixed using the same powder-to-water ratio as the conventional material. Surface hardness was measured using a Shore D hardness tester, surface roughness was assessed using a digital profilometer, and setting time was evaluated using a standardized penetration method. Data were analyzed using descriptive statistics and one-way ANOVA with a significance level of p ≤ 0.05.

Results: The control group showed slightly higher surface hardness values than the recycled group; however, the difference was statistically non-significant (p = 0.111). The recycled group's mean compressive strength was 23.91 ± 1.88 MPa, while the control groups was 24.85 ± 1.72 MPa. At p = 0.274, the difference was not statistically significant (p = 0.274). The recycled group had considerably greater surface roughness values (p = 0.004). Additionally, recycled dental stone showed a little longer setting time, although the difference was not statistically significant (p = 0.146).

Conclusion: Recycling dental stone resulted in a slight non-significant reduction in surface hardness and compressive strength, a significant increase in surface roughness, and a slight non-significant increase in setting time. The recycled material retained satisfactory mechanical qualities in spite of these modifications, indicating its possible application as a cost-effective and sustainable substitute in dental labs.

Keywords:

Recycled dental stone, gypsum recycling, type III dental stone, surface roughness, sustainable dentistry.

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