Screw-retained implant bridge with MUA connection

Dr Antonino Cacioppo

Thu. 19. June 2025

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A 72-year-old patient in good general health presented with partial edentulism in the maxillary posterior region. The main goal was to achieve a rapid fixed prosthetic rehabilitation. After clinical and radiographic (2D and 3D) analysis, it was decided to proceed with a screw-retained bridge on implants, using multi-unit abutment connections to compensate for angulation and z-axis discrepancies. After guided surgery to place two internal hexagonal/conical connection implants, osseointegration time was allowed before prosthetic loading. The patient was informed that the entire prosthetic treatment would be completed on one day, since there would be no need for an external laboratory.

Materials

The following implant components (IPD Dental Group; Fig. 1) were used:

multi-unit abutments, to ensure proper management of insertion and z-axis stresses;
ProCam scan bodies, for accurate intra-oral scanning; and
ProCam titanium bases (Ti-bases), to ensure a precise connection between the implants and prosthesis.

The use of compatible components optimised for a digital workflow resulted in a well-fitting and functional prosthesis.

Chairside workflow

Intra-oral scanning
After postoperative healing of the implants, multi-unit abutments and ProCam scan bodies were placed over the implants, and data was acquired with the Medit i700 wireless intra-oral scanner (Figs. 2a & b). The use of the intra-oral scanner allowed us to avoid physical impressions, thereby reducing patient discomfort. It also allowed for the capture of a detailed and accurate digital representation of the implant connections and enabled real-time evaluation of the scan quality.

The use of intra-oral scanners to capture impressions has demonstrated high accuracy compared with conventional techniques.^1, 2 The importance of ensuring a precise intra-oral scan is often under-estimated, and accurate intra-oral data capture is the true starting point for a successful restoration. Accurate transfer of the implant position is essential for achieving a perfect match between the digital design and clinical reality. Having an optimised geometry and being made of a highly readable scanning material, the ProCam scan bodies allowed the position of the implants and the profile of the peri-implant tissue to be captured with extreme fidelity (Fig. 3).

Figs. 2a & b:: Intra-oral scanning using ProCam scan bodies.

Fig. 2b

Fig. 3: Extreme fidelity of capture of the implant position and surrounding tissue profile using the ProCam scan bodies.

Design
Once the STL file of the scan had been obtained, the prosthesis was digitally designed in the RealGUIDE CAD+ software (3DIEMME), according to the following criteria:

precise fit on the ProCam Ti-bases;
passivity of the structure to reduce stress;
occlusion optimisation; and
natural aesthetics through advanced design.

The implant base was then fabricated using Ti-base custom interfaces. A key technical detail comes into play here: the ability to take advantage of a special 50 μm printing offset, designed to ensure the appropriate space for the cement and optimise the accuracy of fit between the 3D-printed part and the Ti-base. This seemingly minor detail turned out to be essential for achieving effective cementation, eliminating any tension and ensuring perfect adhesion of the anatomical part to the implant base. The ability to modify the design in real time made the design phase extremely efficient (Figs. 4a-c). The use of CAD/CAM technologies in fixed implant prosthetics has shown excellent results in terms of precision and fit.³

Figs. 14a–c:: Bridge design in RealGUIDE CAD+.

Fig. 4b

Fig. 4c

Dfab 3D printing

Once the modelling was complete, the file was sent to the Dfab 3D printer (RD-Printing; Fig. 5) for fabrication of the high-strength hybrid polymer prosthesis. The total printing time was 25 minutes. The material selected was Irix Max Photoshade (DWS Systems; Fig. 6), a ceramic-filled hybrid composite that is biocompatible, durable and highly aesthetic. Direct printing assured:

high accuracy without the need for retouching;
smooth surface and defined details; and
natural colour gradient owing to resin layering enabled by Photoshade technology.

The accuracy of 3D printing compared with conventional techniques is supported by clinical studies, which have demonstrated high reproducibility and prosthetic fit.^4, 5

Fig. 5: Dfab 3D printer.

Fig. 6: Irix Max Photoshade Dfab cartridge.

Dfab employs tilted stereolithography (TSLA) technology, designed for chairside manufacture, and works with disposable cartridges, available in small, medium and large versions depending on the volume of material contained, allowing the workflow to be optimised according to the number and size of restorations to be printed. An evolution of stereolithography, TSLA is a versatile technology that uses an inclined build platform and a moving high-viscosity material to create a cascade effect that allows heavy fillers to be mixed evenly during printing. This technology increases printing speed and allows the size of the supporting structures to be reduced.

The process begins by loading the CAD restoration as an STL file into the Photoshade software, which automatically positions and correctly supports it for the best accuracy and fit with the occlusal surface facing the platform and the marginal and internal surfaces free of support and facing the cartridge reservoir. The desired Photoshade colour gradient and positioning of the cervical and incisal colour boundaries are then selected, the width of the interspace resulting in a sharp (narrow) or gradual (wider) transition (Figs. 7a-c). Once the appearance of the restoration is approved, the printing process can begin. A disposable Dfab cartridge containing the printing reservoir of the selected material and size is loaded into the top of Dfab, along with the printing media and disposable platform. The top of Dfab is closed, and the cartridge is tilted at a 45° angle. Printing is initiated by the Photoshade Pro software, and a continuous flow of material is begun and maintained by gravity and a quiet peristaltic pump (Fig. 8). At this stage, the software precisely controls the extrusion of material in two different gradations to produce the desired colour gradient of the restoration. The blue UV laser beam is directed at the surface of the composite, selectively polymerising it to create the object. The build platform is gradually lowered into the resin tank, part of the material’s cartridge, and the process is repeated layer by layer until the object is complete.

Figs. 17a–c:: Selecting the shade and the colour gradient in the Photoshade software.

Fig. 7b

Fig. 7c

Dfab is then opened, and the top section tilted to return the build platform and used cartridge to their original horizontal position, and they are removed, starting with the platform, to prevent unpolymerised liquid material from dripping into the printer. To remove any residual unpolymerised liquid composite, the platform containing the restoration is washed with 95% ethanol for 1–2 minutes in a special shaker container. The restoration is then manually separated from the platform—without risking damage to adjacent surfaces—by grasping the restoration and using a twisting motion to break the very thin supports. Any unpolymerised composite residue in areas such as the occlusal and internal surfaces can be removed with a flat brush dipped in 95% ethanol. Finally, post-polymerisation is performed to improve the properties of the restorative material. A proprietary dual-energy (UV light and heat) unit (Dcure, RD-Printing) is used (Fig. 9) with an automated, material-specific cycle that takes approximately 9 minutes to complete.

Fig. 8: Video graphics still image of a phase of the Dfab printing process.

Fig. 9: Dcure post-polymerisation unit.

Finishing and clinical evaluation
After printing, the bridge was washed with 94%–96% ethanol (food grade), post-polymerised and finished directly in the clinic (Figs. 10a-c) with the following procedures:

polishing and characterisation with a glaze (DEI experience Seal Coat Fast, DEI Italia) to improve the aesthetics (Figs. 11a-c);
verification of passive fit on the ProCam Ti-bases;
extra-oral cementation on the ProCam Ti-bases using MultiLink Hybrid Abutment cement (Ivoclar); and
verification of occlusion and function.

Once screwed to the implants, the prosthesis demonstrated excellent stability and seamless integration with the peri-implant tissue (Fig. 12). No occlusal retouching was performed.

Fig. 10a: Bridge after washing, still on the build platform.

Fig. 10b: Bridge after support removal.

Fig. 10c: Bridge after surface finishing.

Figs. 11a–c: Polished and glazed bridge.

Fig. 11b

Fig. 11c

Fig. 12: Bridge in position on the implants, demonstrating seamless integration with the peri-implant bone.

Outcome

The entire digital workflow was completed in one session, allowing the patient to receive a definitive prosthesis without a long wait. The chairside approach significantly reduced treatment time by eliminating the need to send the case to an outside laboratory. The main benefits achieved were:

accurate fit to the implant sites;
excellent aesthetics thanks to Irix Max Photoshade;
minimal post-production retouching; and
immediate patient comfort.

Discussion

The chairside 3D-printing workflow represents a revolution in implant prosthetics, enabling the clinician to:

reduce treatment time;
maintain complete control over the prosthesis; and
eliminate the errors that can arise in data transfer to the laboratory.

The use of intra-oral scanners for data acquisition is now an established reality, and numerous studies have confirmed their accuracy and reliability in implant prosthetics.^6, 7 Digital prostheses have demonstrated excellent accuracy of fit in comparative analyses with conventional methods.⁸ The integration of digital technologies into the chairside workflow allows for optimisation of treatment management, reduction of treatment time and improvement of patient comfort.^9, 10 The use of IPD components ensured a stable and predictable implant connection. In particular, the ProCam scan bodies enabled reliable and detailed scanning by correcting volumetric mesh distortions using advanced mathematical algorithms and precise offset adjustments, and the ProCam Ti-bases ensured excellent implant–prosthesis coupling accuracy. The combination of the Medit i700 wireless, RealGUIDE CAD+, Dfab and Irix Max Photoshade made the process extremely efficient and demonstrated how digital technologies can transform the approach to implant prostheses.

Conclusion

This clinical case demonstrates that the fabrication of a screw-retained bridge on implants using a chairside 3D-printing workflow is a clinically viable and efficient option. The dentist can manage all steps of the process independently, reducing time and cost without compromising quality and accuracy. Dfab’s TSLA printing technology enables immediate, customised and highly predictable solutions that improve the patient experience and optimise practice operations.

Editorial note:

This article was published in 3D printing–international magazine of dental printing technology Vol. 5, Issue 1/2025. The list of references can be found here.