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Objectives The accuracy, especially precision of intraoral scans of various intraoral scanning devices using various implant systems, positions and additive manufacturing methods has not been studied sufficiently yet. This in-vitro study evaluated the accumulative effect of intraoral scanning (IOS), additive manufacturing (AM), implant angulation, and implant analog system on the precision of definitive implant cast. Materials and Methods A partially edentulous reference (Ref) cast presenting a case of a 3-unit implant supported (BLT RC, Straumann) fixed dental prosthesis in the posterior region was selected. The cast base was prepared using 5 precision spheres and the cast fitted using titanium implant scan bodies (3Shape) and scanned using a laser scanning head device (ALTERA; Nikon) producing a reference Ni data set (n = 1). A second reference data set (T4, n = 10) was prepared using digital scan of the Ref cast using an intraoral scanner (Trios 4, 3Shape A/S). Test quadrant cast were produced out of the digital scans using three different additive manufacturing (AM) devices (MAX UV385 (Asiga), PRO 4K65 UV (Asiga) and NextDent 5100 (3D Systems)) and 3 implant analog systems (Accurate Analog for Printed Models (Elos Medtech), DIM-ANALOG (nt-trading), and RC Repositionable Implant Analog (Straumann)) (n = 90). Open-tray splinted vinyl polysiloxane impressions (n = 10) were made of the Ref cast and control casts poured using Type IV dental stone. Stone and AM casts were thereafter digitized using a laboratory scanner (E4; 3Shape A/S). Implant local and global precision (3D distance, angulation) was assessed comparing reference (Ni, T4), test (AM), and control (stone) groups with a metrology software (Geomagic Control X; 3D Systems). Shapiro-Wilk and Leven’s tests were used to evaluate data normality and homogeneity of variance respectively. Student’s t-test, two-way, and three-way ANOVA models as well as Post hoc Tukey-HSD tests were used (α ≤ .05). Results Digital scans made with Trios 4 (3Shape A/S) showed mostly similar precision to stone casts. However, IOS was significantly more precise in capturing angulation between the implants than control stone casts (P = .05). Both groups showed clinically significant global angulation precision (> 0.40°). Global angulation precision of the distal implant was significantly better in AM models rather than IOS (P ≤ .05, ∆≥0.26°). All local measurements showed a similar precision between test AM and control stone models (P > .05). However, global angulation precision of both implants was mostly better in AM models rather than in the control group (P ≤ 0.05, ∆≥0.21°). The AM device MAX UV385 (Asiga) had a significantly higher precision than NextDent 5100 (3D Systems) (P = .05). The implant analog system DIM-ANALOG (nt-trading) provided significantly less local angulation precision than Repositionable Implant Analog (Straumann) (P = .01). Conclusions Digital scans reproduce similar distance but higher angulation precision between implants compared to stone casts. Clinical Relevance: AM device and implant analog system choice has a significant effect on the precision of AM models. |
