Purpose Additive manufacturing (AM) in prosthodontics is used as an alternative to casting or milling. Various techniques and materials are available for the additive manufacturing of the fixed and removable tooth‐supported restorations, but there is a lack of evidence on the accuracy of AM fixed implant‐supported prostheses. Recent studies investigated the accuracy of ceramic AM prostheses. Therefore, the aim of this systematic review was to evaluate the accuracy of additively manufactured metal, ceramic or polymers, and screw‐ or cement‐retained fixed implant‐supported prostheses. Materials and Methods Two calibrated investigators performed an electronic search of relevant publications in the English language following selected PICOS criteria and using a well‐defined search strategy (latest search date—1st of June, 2021). Based on the exclusion criteria (no control group, less than five samples per group, 3D printing of the implant abutment part, only subjective evaluation of accuracy, etc.) studies were not included in the review. Quantitative data of accuracy evaluation such as marginal gap, strain analysis, and linear measurements was extracted and interpreted. QUADAS‐2 tool was used to assess the risk of methodological bias of all included studies. Results Sixteen in vitro studies were selected for the final analysis. Six of the selected studies evaluated screw‐retained restorations and 10 cement‐retained implant‐supported restorations. Only 4 publications concluded that AM restorations were more accurate than conventionally made (cast or milled) ones. The most common finding was that AM restorations were more accurate than cast and demonstrated less or similar accuracy compared to milled ones (n = 10 studies). Detected marginal discrepancies mean values of the AM prosthesis varied from 23 to more than 200 µm, but most of them were categorized as clinically acceptable. Conclusions AM implant‐supported fixed prostheses demonstrate similar accuracy compared to conventional and computer‐aided design and computer‐aided manufacturing techniques in vitro. Detected inaccuracies of AM restorations do not exceed clinically acceptable limits. Clinical studies with longer follow‐up periods are needed to show the reliability of AM prostheses.

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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.

Objectives The accuracy of intraoral digital scans using various intraoral scanning devices regarding additive manufacturing and implant position and system is not evaluated sufficiently yet. To evaluate in-vitro the accumulative effect of intraoral scanning (IOS), additive manufacturing (AM), implant angulation, and implant analog system on the trueness of the definitive implant cast. Materials and Methods A case of a three-unit implant-supported (BLT RC, Straumann) fixed dental prosthesis in a posterior region was simulated on the reference (Ref) cast. 5 precision spheres were placed on the cast base. Ref cast was fitted with titanium implant scan bodies (3Shape A/S) and scanned with a coordinate measurement machine equipped with a laser scanning head (ALTERA; Nikon) producing a reference Ni data set (n = 1). Digital scans of the Ref cast were taken with Trios 4 (3Shape A/S) which served as a second reference data set (T4, n = 10). Each digital scan was used to produce physical test quadrant cast with 3 AM machines for 3 implant analog systems (n = 90). Tested implant analog systems: Accurate Analog for Printed Models (Elos Medtech), DIM-ANALOG (nt-trading), and RC Repositionable Implant Analog (Straumann). Tested additive manufacturing (AM) devices: MAX UV385 (Asiga), PRO 4K65 UV (Asiga), and NextDent 5100 (3D Systems). Conventional open-tray splinted vinyl polysiloxane impressions (n = 10) were made of the Ref cast and control casts were poured with Type IV dental stone. Stone and AM casts were fitted with the same titanium implant scan bodies (3Shape A/S) and digitized using a laboratory scanner (E4; 3Shape A/S). Implant local and global trueness (3D distance, angulation) was assessed comparing reference (Ni, T4), test (AM), and control (stone) groups with metrology software (Geomagic Control X; 3D Systems). To assess data normality and homogeneity of variance Shapiro-Wilk and Leven’s tests were used respectively. Student’s t-test, two-way, and three-way ANOVA models were used for statistically significant differences between data groups estimation. A Post hoc Tukey-HSD test for further ANOVA analysis was used. For all tests and models, α was assigned to be less than 0.05. Results Digital scans showed higher 3D distance trueness between implants compared to stone casts (P = .00). The trueness of additively manufactured casts was mostly similar to or lower than IOS scans (P ≤ .05). Only in a few instances did the AM casts produced with PRO (Asiga) and Nextdent 5100 (3D Systems) and equipped with Nt-trading and Elos implant analogs showed higher angulation trueness than digital scans (P < .05). AM casts showed better 3D distance and lower angular trueness than stone casts (P < .05). Higher 3D distance deviations were introduced by Nextdent 5100 (3D Systems) AM device and Nt-trading system (P < .05). Implant angulation influence on trueness was non-significant (P > .05). Conclusions Within the limitations of this in vitro study, digital scans and additively manufactured casts reproduced the distance between the implants with higher trueness compared to stone casts. All test and control groups had clinically significant angulation deviations. Clinical Relevance: AM device and implant analog system have a significant effect on the trueness of AM models.