Vat Photopolymerization 3D Printing in Dentistry: A Comprehensive Review of Actual Popular Technologies

Abstract

In this comprehensive review, the current state of the art and recent advances in 3D printing in dentistry are explored. This article provides an overview of the fundamental principles of 3D printing with a focus on vat photopolymerization (VP), the most commonly used technological principle in dental practice, which includes SLA, DLP, and LCD (or mSLA) technologies. The advantages, disadvantages, and shortcomings of these technologies are also discussed. This article delves into the key stages of the dental 3D printing process, from computer-aided design (CAD) to postprocessing, emphasizing the importance of postrinsing and postcuring to ensure the biocompatibility of custom-made medical devices. Legal considerations and regulatory obligations related to the production of custom medical devices through 3D printing are also addressed. This article serves as a valuable resource for dental practitioners, researchers, and health care professionals interested in applying this innovative technology in clinical practice.

Keywords: 3D printing; accuracy; dental additive manufacturing; dentistry; vat photopolymerization.

Figure 4

Summary of the differences between the three resin tank polymerization printing processes (version of [23]).

Figure 1

The seven categories of 3D printing technology.

Figure 2

Operation of stereolithography (laser) printing technology. The orange arrow indicates that the platform lifts upward, while the element is being printed.

Figure 3

Operation of DLP printing technology. The pink arrow indicates that the platform lifts upward, while the element is being printed.

Figure 5

Difference in printing speed between SLA and DLP (due to their great heterogeneity, LCD printers are not represented here). The surfaces required for the manufacture of the various elements represented by the dashed blue lines are located in the area where DLP prints faster. FPD = fixed partial denture; RD = removable denture.

Figure 6

Example of occlusal splint printing planning based on artificial intelligence using the Rayware Cloud software (Sprintray, Los Angeles, CA, USA). After the stl design file was uploaded, and the printing resin was selected (Keysplint Soft, Keystone Industries, Gibbstown, NJ, USA), the positioning of the elements to be printed and the orientation of the splints were automatically generated using artificial intelligence.

Figure 7

Differences in printing accuracy between SLA and DLP (due to their great heterogeneity, LCD printers are not represented here). FPD = fixed partial denture; RD = removable denture.

Figure 8

Examples of printing support structure placement: (a) correct positioning of printing supports to print two hollowed full wax-up models—the entire useful upper surface is free of support structures; (b) incorrect positioning of printing supports for temporary shells—prosthetic element contact with the intrados should be minimized.

Figure 9

Basing models: (a) stl file from an intraoral scanner after acquisition. This non-closed geometry cannot be printed; (b) the same impression after cleaning and basing with specific software (Inlab 22, Dentsply Sirona, Charlotte, NC, USA). Numerous parameters are available for adjusting the model geometry or performing die placements. This continuous geometry can be printed; (c) the same impression automatically based with a slicer (PreForm, Formlabs, Somerville, MA, USA). The basing is less efficient but saves time.

Figure 10

The four typical angles for positioning an item on a build plate; an example of a 4-unit bridge.

Figure 11

Impact of the build orientation on the reduction in the contact surface for each layer. This reduction reduces the peeling force required to detach the print from the vat at each layer and thus limits the risk of printing failures.

Figure 12

Selection of an optimal orientation based on various parameters (time, precision, and risk of failure). A green dot indicates a good performance regarding a specific parameter, a yellow dot indicates average performance, and red dot indicates inferior performance. There is no ideal orientation; it is the experience of the practitioner (or the artificial intelligence of the slicer) that guides the choice.

Figure 13

Surgical guide before (a) and immediately after removal of the printing support structures (b). Additional polishing was required (c). The resin used was dental SG (Formlabs, Somerville, MA, USA) printed on Form 3B+ (Formlabs, Somerville, MA, USA).