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. 2021 Dec;13(6):351-360.
doi: 10.4047/jap.2021.13.6.351. Epub 2021 Dec 22.

Efficiency of occlusal and interproximal adjustments in CAD-CAM manufactured single implant crowns - cast-free vs 3D printed cast-based

Tobias Graf  1 , Jan-Frederik Güth  1 , Christian Diegritz  2 , Anja Liebermann  3 , Josef Schweiger  3 , Oliver Schubert  3
Affiliations

Efficiency of occlusal and interproximal adjustments in CAD-CAM manufactured single implant crowns - cast-free vs 3D printed cast-based

Tobias Graf et al. J Adv Prosthodont. 2021 Dec.

Abstract

Purpose: The aim of this study was to evaluate the efficiency of occlusal and interproximal adjustments of single implant crowns (SIC), comparing a digital cast-free approach (CF) and a protocol using 3D printed casts (PC).

Materials and methods: A titanium implant was inserted at position of lower right first molar in a typodont. The implant position was scanned using an intraoral scanner and SICs were fabricated accordingly. Ten crowns (CF; n = 10) were subject to a digital cast-free workflow without any labside occlusal and interproximal modifications. Ten other identical crowns (PC) were adjusted to 3D printed casts before delivery. All crowns were then adapted to the testing model, simulating chair-side adjustments during clinical placement. Adjustment time, quantity of adjustments, and contact relationship were assessed. Data were analyzed using SPSS software (P < .05).

Results: Median and interquartile range (IQR) of clinical adjustment time was 02:44 (IQR 00:45) minutes in group CF and 01:46 (IQR 00:21) minutes in group PC. Laboratory and clinical adjustment time in group PC was 04:25 (IQR 00:59) minutes in total. Mean and standard deviation (±SD) of root mean squared error (RMSE) of quantity of clinical adjustments was 45 ± 7 µm in group CF and 34 ± 6 µm in group PC. RMSE of total adjustments was 61 ± 11 µm in group PC. Quality of occlusal contacts was better in group CF.

Conclusion: Time effort for clinical adjustments was higher in the cast-free protocol, whereas quantity of modifications was lower, and the occlusal contact relationship was found more favourable.

Keywords: 3D printing; CAD-CAM; Cast-free; Digital workflow; Single implant crown; Time-efficiency.

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Figures

Fig. 1
Fig. 1. Experimental sequence.
Fig. 2
Fig. 2. Intraoral scanners of testing model (Co-Cr alloy) equipped with scan post and scanbody (A). CAD of hybrid abutment crown (B).
Fig. 3
Fig. 3. Hybrid abutment crowns (random selection) mounted on referencing scan fixture (A), on testing model, mimicking the clinical situation (B), and placed on 3D printed cast (C).
Fig. 4
Fig. 4. Spherical geometries selected (red) for data alignment (A) and difference image of contact areas after superimposition (B).
Fig. 5
Fig. 5. Median adjustment time in the different groups and at different processing stages in minutes.
Fig. 6
Fig. 6. Mean quantity (± 1 SD) of adjustments in the different groups and at different processing stages in microns.
See this image and copyright information in PMC

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