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]. The conventional dental impression technique has many advantages. It is a well-known, relatively simple, and highly accurate technique that requires minimal and simple equipment [10]. However, conventional impressions involve many steps, such as tray selection, application of tray adhesives, type of impression material and technique, disinfection, shipping to a dental laboratory, and pouring the impression with dental stone to prepare the working cast and dies [10; 11]. Since this procedure is highly technique-sensitive, inaccuracies in any of these steps can lead to distortion of the master model, resulting in errors in the final dental prosthesis. Therefore, each step must be performed as precisely as possible. The concept of digital impressions using an intraoral scanner (IOS) has been employed in dentistry since the 1980s, and its use instead of conventional impression techniques has been rapidly increasing for the fabrication of fixed dental prostheses [12]. Digital impression technology is believed to potentially solve the problems and challenges of conventional impressions, is easier to use by the clinician, and is highly accepted by patients [10; 11]. Impression trays are not involved in digital impression-taking, which helps overcome the problems related to improper tray selection and separation of the material from the tray. Delay and improper pouring of conventional impressions are common procedures, leading to distortion of impressions [11]. A previous study measured the accessible marginal inaccuracy and the internal fit to evaluate the precision of crowns fabricated using conventional and digital impressions and reported that crowns fabricated using digital impressions were as accurate as those fabricated using conventional impressions [13]. In addition, many researchers have found that the marginal adaptation of all-ceramic crowns fabricated using digital impressions is better than the marginal adaptation of all-ceramic crowns using conventional impressions [14; 15; 16]. In contrast, other studies reported no significant difference between the marginal adaptation and the internal fit of all-ceramic crowns and short fixed partial dentures using digital versus conventional impression techniques [17; 18]. The previous study evaluated the impression accuracy of quadrant impressions and found that the precision of digital quadrant impressions was comparable to that of conventional methods; however, the precision differed significantly between the digital impression systems [19]. To the best of the authors' knowledge, this is the first study that compares the casts generated by several impression materials and techniques commonly used to fabricate provisional and definitive fixed prostheses. The purpose of this study was to compare conventional impression (putty and light body consistencies polyvinyl siloxane [PVS], alginate [ALG], and vinyl polysiloxane based alginate alternative [AA]) and digital impression techniques in terms of accuracy, dimensional stability, and ability to produce clinically acceptable casts. 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 (horizontal straight [HS], horizontal curved [HC], horizontal cross-arch [HCA], and vertical [V]), 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.