Reliability of Metal 3D Printing with Respect to the Marginal Fit of Fixed Dental Prostheses: A Systematic Review and Meta-Analysis

Abstract

Three-dimensional (3D) printing technologies have been widely used to manufacture crowns and frameworks for fixed dental prostheses. This systematic review and meta-analysis aimed to assess the reliability of the marginal fit of 3D-printed cobalt-chromium-based fixed dental prostheses in comparison to conventional casting methods. Articles published until 25 June 2020, reporting the marginal fit of fixed prostheses fabricated with metal 3D printing, were searched using electronic literature databases. After the screening and quality assessment, 21 eligible peer-reviewed articles were selected. Meta-analysis revealed that the marginal gap of the prostheses manufactured using 3D printing was significantly smaller compared to that manufactured using casting methods (standard mean difference (95% CI): −0.92 (−1.45, −0.38); Z = −3.37; p = 0.0008). The estimated difference between the single and multi-unit types did not differ significantly (p = 0.3573). In the subgroup analysis for the measurement methods, the tendency of marginal discrepancy between the 3D printing and casting groups was significantly different between articles that used direct observation and those that used the silicone replica technique (p < 0.001). Metal 3D printing technologies appear reliable as an alternative to casting methods in terms of the fit of the fixed dental prostheses. In order to analyze the factors influencing manufacturing and confirm the results of this review, further controlled laboratory and clinical studies are required.

The effect of the digital manufacturing technique of cantilevered implant-supported frameworks on abutment screw preload

“…Microscopic readings showed that implant abutment connection misfit is significantly affected by the digital manufacturing technique, which is in agreement with previous literature. 25 32 The 3DP group showed lower implant abutment misfit than the CAD-cast group. One possible reason is that CAD-cast manufacturing technique is affected by the ability and experience of the laboratory technician in casting the CAD-cast frameworks.…”

“…A systematic review evaluated the fit of casted, milled and 3DP abutments and found that 3DP had poor internal fit compared to other manufacturing methods, which would ultimately affect the RTV. 32 Several studies showed that misfit ranging between 10 and 150 µm would be clinically acceptable and tolerated in the long term. 37 38 39 41 42 43 RTV describes the amount of force needed to un-torque a screw and it has been used as a measurement of preload in multiple studies to evaluate joint stability.…”

“… 29 30 Ramalho et al 31 compared the fit of abutments manufactured using digital, partial digital, and conventional methods and showed higher implant abutment connection misfit in fully digitalized abutments. In contrast, Bae et al 32 conducted a systematic review to compare the reliability of the marginal fit of 3DP and conventional casting, and they concluded that compared to conventional casting, 3DP techniques are reliable for the construction of fixed dental prostheses with an accurate marginal fit. To the best of our knowledge, there are no studies in the literature that compared the effect of different digital manufacturing techniques of ICFDPs on abutment screw’s preload.…”

Accuracy of Fixed Implant‐Supported Dental Prostheses Additively Manufactured by Metal, Ceramic, or Polymer: A Systematic Review

“…45 Several reviews have been published about additively manufactured dental restorations. 2,5,10,46,47 The accuracy of the tooth-and implant-supported restorations has only been documented in general, but this study serves the relevant systematized data about the accuracy of AM fixed implant-supported prostheses exceptionally. Because of the manufacturing and construction differences between tooth-and implant-supported restorations such as scanning of the preparation margin or capturing the virtual position of the implant with scan body, tolerance of marginal gap discrepancies or passivity, fixation type, and the more specific data about implant-supported restorations was required.…”

“…Previous systematic reviews have assessed metal AM tooth‐supported fixed or removable prostheses accuracy 10,36–39 . However, studies evaluating the accuracy of the AM implant‐supported prosthesis have not yet been reviewed systematically.…”