Comparative Evaluation of Compatibility of Type III and Type IV Gypsum with Addition Silicone Impression Material—An In Vitro Study

Introduction: Types III and IV gypsum are widely used in dentistry to pour impressions and produce working models; however, there is limited research on the differences between the two types regarding compatibility with addition silicone impression materials.Aim: To evaluate the compatibility of type III and three commercially available type IV gypsum with addition silicone impression material in accordance with American National Standards Institute/American Dental Association (ANSI/ADA) Specification No. 19. Materials and methodology: Suitable specimens were prepared using the metal die.A total of 80 impressions were made with addition silicone impression material (FLEXCEED vinyl polysiloxane impression material) of a stainless steel die and poured into 80 samples, divided into 4 groups with 20 samples in each group.Group I: 20 samples of type III dental stone, Neelkanth Dentstone; group II: 20 samples of type IV Die stone, Kalabhai Karson; group III: 20 samples of type IV die stone, Neelkanth die stone plaster; group IV: 20 samples of type IV die stone, Samit die stone.Results: In this study, two types of gypsum, i.e., type III dental stone and type IV dental stone (high strength), were studied for their dimensional stability, dimensional accuracy, and surface roughness.There was a statistically significant difference in dimensional stability, dimensional accuracy, and surface roughness between the control and type III (Neelkanth), type IV (Kalabhai), type IV (Neelkanth die stone), and type IV (Samit).There was no statistically significant difference found between the type IV brands for dimensional stability, dimensional accuracy, and surface roughness.Conclusion: Type IV gypsum was more stable than type III gypsum in terms of replicating the depth in micrometers.There was no significant difference in stability within the brands chosen for the type IV gypsum.Type IV gypsum was more accurate than type III gypsum in terms of replicating the length of the lines in millimeters.There was no significant difference in accuracy within the brands chosen for the type IV gypsum.The surface of type III gypsum was rougher than type IV gypsum in terms of replicating the length of the lines in millimeters.The brand Kalabhai type IV was rougher than the other brands, such as Neelkanth and Samit.