Vol. 11, Issue 4, Part C (2025)
Comparison of dimensional accuracy between manually-mixed and vacuum- mixed gypsum product for fixed partial denture
Md. Mamunur Rashid, Md. Al-Amin Sarkar, Md. Alamgir Kabir, Musammat Jannatul Ferdous, Ashik Abdullah, Md. Majharul Islam Bhuyan and Raisul Islam
Background: Accurate duplication of teeth plays a vital role in the fabrication of fixed partial denture. The ultimate success of a dental restoration depends mainly on accuracy of die material (gypsum products), which exhibit dimensional change while setting and hardening process so accurate mixing techniques are very essential. There are several mixing techniques such as manually, mechanical and vacuum-mixed techniques.
Objective: To compare dimensional accuracy between manually and vacuum mixed gypsum products.
Materials and Methods: This was a comparative and an in-vitro study conducted in the department of prosthodontics, with 64 dies that had been prepared from the mold with different mixing techniques. The non- probability purposive sampling technique was utilized with set inclusion and exclusion criteria. Sixty-four gypsum dies prepared from master die using addition silicone impression materials. In group A 32 gypsum dies made from manually mixed technique, and group B 32 gypsum dies made from vacuum mixed technique. Three measurements were done for each die sample by measuring tooth length, width and tooth height by using a digital slide caliper. The dimension of the experimental dies was compared each other and also compared with the dimensions of master die to get linear dimensional discrepancy.
Results: The mean value of length, height and width of dies from group A and group B were tabulated and unpaired t-test were performed. The probability value was <.001 (<.05) which is highly significant at 0.1% level. Conclusion: It could be concluded that vacuum mixing technique is more appropriate method for pouring gypsum dies in term of dimensional accuracy than manually mixed technique.
Conclusion: Dies produced from vacuum mixing technique showed a significantly greater dimensional accuracy compared with dies produced from manually mixed technique. Within the limitations of this study, it could be concluded that vacuum mixing technique is an appropriate method to pouring gypsum dies in term of dimensional accuracy than manually mixed technique.
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