Comparative evaluation of the accuracy of dental stone casts fabricated using different technologies and impression materials: an uncontrolled clinical and laboratory study

BACKGROUND: Despite the availability of studies addressing the accuracy of various impression materials and digital methods for jaw model acquisition, the comparative effectiveness of these approaches remains insufficiently investigated, underscoring the relevance of the present study.

AIM: The work aimed to comparatively assess the accuracy of dental stone jaw casts obtained by conventional methods using different impression materials and of digital models produced by intraoral scanning.

METHODS: The study included 30 patients with intact dentitions. For each patient, impressions were obtained using alginate, A-silicone, and C-silicone materials, and intraoral scanning was performed. Dental stone casts were fabricated from the analog impressions: solid casts from alginate impressions and casts with removable dies from silicone impressions using the Giroform system (Amann Girrbach AG, Austria) and a conventional technique. All physical models and digital scans were converted to 3D STL format. Comparative analysis of the accuracy of anatomic detail reproduction (teeth 1.6 and 2.1; ISO/FDI designation) was performed using Geomagic Control X (3D Systems, USA) by superimposition and deviation assessment.

RESULTS: The highest accuracy (minimal deviation from the digital reference) was observed for solid casts fabricated from alginate impressions: deviation of 0.0031 ± 0.0005 mm for tooth 1.6 and 0.0029 ± 0.0004 mm for tooth 2.1. Among casts with removable dies, those fabricated using the Giroform system demonstrated the best results: deviation of 0.0037 ± 0.0003 mm for tooth 1.6 and 0.0036 ± 0.0003 mm for tooth 2.1. The lowest accuracy was recorded for casts with removable dies fabricated by the conventional method from C-silicone impressions, with maximum deviations of 0.0066 ± 0.0007 mm and 0.0065 ± 0.0007 mm, respectively. All intergroup differences were significant (p < 0.001).

CONCLUSION: Digital models obtained by intraoral scanning and solid casts fabricated from alginate impressions demonstrate high and comparable accuracy. For fabrication of casts with removable dies, use of the Giroform system substantially improves accuracy compared with the conventional technique. These findings are clinically relevant for selecting the optimal method for producing working models in prosthodontics.