Abstract
Accurate impression-making is considered a vital step in the fabrication of fixed dental prostheses. There is a paucity of studies that compare the casts generated by various impression materials and techniques that are commonly used for the fabrication of provisional and definitive fixed prostheses. The aim of this study is to compare the accuracy of casts obtained using conventional impression and digital impression techniques. Thirty impressions were made for the typodont model (10 impressions each of polyvinyl siloxane, alginate, and alginate alternative materials). Ten digital models were printed from the same model using a TRIOS-3 3Shape intraoral scanner. Accuracy was assessed by measuring four dimensions (horizontal anteroposterior straight, horizontal anteroposterior curved, horizontal cross-arch, and vertical). A one-way ANOVA and Tukey’s test (α = 0.05) were used to analyze data. A statistically significant difference in the four dimensions of the stone casts and digital models was observed among the four groups (exception: between alginate alternative and 2-step putty–light body impression in the horizontal anteroposterior straight, horizontal anteroposterior curved, and horizontal cross-arch dimensions; between alginate and alginate alternative in the horizontal anteroposterior curved dimension; between alginate and 2-step putty–light body impression in the horizontal anteroposterior curved dimension; and between alginate alternative and digital in the vertical dimension). Polyvinyl siloxane had the highest accuracy compared to casts obtained from other impression materials and digital impressions.
Highlights
Dental prosthetic rehabilitations are characterized by a series of ordered clinical and laboratory steps, during which several types of impression materials and techniques are necessary [1]
This study examined the following two null hypotheses: (1) there will be no statistically significant differences in accuracy between casts made by the two impression modalities and the typodont master model at each of the four locations, and (2) there will be no statistically significant differences in dimensions measured at each of the four locations between the casts generated using the conventional and digital impression techniques
The results of this study indicated that stone casts generated using conventional impression and pouring techniques have a higher linear dimensional accuracy than 3Dprinted casts, which contradicts the findings reported by recent studies [27,28]
Summary
Dental prosthetic rehabilitations are characterized by a series of ordered clinical and laboratory steps, during which several types of impression materials and techniques are necessary [1]. Accurate impression-making is considered a vital step in the fabrication of fixed dental prostheses. The current impression materials available for fixed prosthodontic procedures, including polyvinyl siloxanes and polyether, offer an excellent reproduction of surface details of the tooth preparations, as demonstrated by clinical observation and scientific evidence [2,3,4,5,6]. A common technique for making impressions with polyvinyl siloxanes is the putty– light body impression technique. Two different techniques are commonly used: the one-step and two-step putty–light body impression techniques. The two-step putty–light body technique has been reported to be more accurate than the one-step technique. In the two-step putty–light body technique, there is a uniform space for the light body material to polymerize with minimal shrinkage, and the details are recorded by the light body material only [7,8,9]
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