Digital Diagnostic versus Conventional Casts

Dental diagnostic casts are fundamental instruments in prosthodontics, orthodontics, and restorative dentistry, serving as three-dimensional replicas of the oral hard and soft tissues upon which clinical and laboratory procedures are planned and executed. Conventional plaster casts, obtained through alginate or polyvinylsiloxane impressions, have constituted the gold standard for decades; however, they are susceptible to material-induced distortions, dimensional instability, and logistical challenges related to storage and transfer. The advent of intraoral scanners (IOS) and computer-aided design/computer-aided manufacturing (CAD/CAM) technologies has enabled the production of digital diagnostic casts that may circumvent many of these limitations. This systematic review aimed to critically evaluate and compare the accuracy, time efficiency, and clinical outcomes of digital diagnostic casts versus conventional casts across prosthodontic, orthodontic, and implant-supported restorative applications, following the PRISMA 2020 guidelines. A systematic electronic search was conducted across PubMed/MEDLINE, Cochrane Library, Scopus, and Google Scholar databases, restricted to publications from 2013 to 2026. Studies were included if they employed a direct comparison between digital and conventional cast-fabrication methods, with dimensional accuracy, time efficiency, or clinical outcomes as primary or secondary endpoints. Both in vitro and in vivo study designs were considered. Risk of bias was assessed using the Risk of Bias tool 2 (ROB 2) for randomized controlled trials and the Newcastle-Ottawa Scale (NOS) for non-randomized studies. A total of 22 studies met the final inclusion criteria. Digital casts generated by stereolithographic (SLA) intraoral scanning demonstrated mean trueness values ranging from 67.5 to 98.23 micrometers (95% CI: 63.43-102.3 µm), compared with conventional stone casts that exhibited dimensional deviations up to 0.61 ± 0.13 mm. Digital impression workflows produced statistically significantly lower mean deviations (0.41 ± 0.09 mm versus 0.61 ± 0.13 mm; p < 0.0001). Patient-reported comfort favored digital impressions (VAS: 8.43 ± 0.8 versus 6.39 ± 0.71; p < 0.00001). Procedural time was shorter for digital workflows in implant prosthodontics (11.95 ± 1.75 min versus 20.47 ± 3.25 min; p < 0.00001), although time advantages were context-dependent. In orthodontic applications, digital and conventional models demonstrated clinically comparable measurements with no statistically significant differences for most diagnostic parameters. Extended-pour alginate and alginate-alternative opposing casts achieved superior occlusal accuracy compared to conventional alginate and three-dimensional (3D)-printed casts. Digital diagnostic casts demonstrate accuracy that is equivalent or superior to conventional casts for most clinical applications, with measurable advantages in patient comfort and procedural efficiency. Nevertheless, clinical context, arch span, and the specific digital technology employed remain critical determinants of diagnostic cast performance. Higher-quality, multi-center randomized trials are needed to definitively establish evidence-based clinical guidelines.