Accuracy of a cast fabricated with the i-Tero digital impression system

Abstract

A decisive factor in the prognosis of dental prostheses is the degree of accuracy in reproducing the intraoral condition. Various impression materials and techniques have been developed to achieve accurate reproducibility in dental casts. However, none have completely overcome the distortions in cast dimensions caused by polymerization of the impression material. A new digital impression technique was recently introduced that was convenient for both the clinician and patient, avoided the errors inherent in an analog impression, and enhanced the accuracy of the corresponding cast. The purpose of this study was to evaluate the accuracy of casts made with this digital impression system compared to casts made with conventional techniques.For comparisons, we used a standardized, stainless steel model that simulated two abutments for a fixed partial denture. Casts were fabricated based on either the i-Tero digital impression system (n=15) or the conventional impression technique, with addition silicone impression material and a die stone (n=15). The abutment and inter-abutment distances were measured on the casts made from the two different types of impressions. Statistical analysis was performed with the ANOVA test (p<0.05), followed by Tukey’s HSD test. The distances measured on the polyurethane casts based on the digital impression technique were not statistically different from those measured on the standardized models. The distances measured on the gypsum cast based on the conventional impression technique were not significantly different from the standardized model, except in height.The major limitation of this investigation was that it was performed in vitro. Thus, the evaluations did not include affects of fluids and soft tissues present in the human oral condition. Within these limitations, we showed that the cast fabricated with the digital impression system displayed reproducibility and accuracy similar to the cast made with the conventional impression technique.