Screw access finding after screw loosening through cemented splinted crowns on non-parallel implants using mixed reality - guided access optimization: A clinical case report

Background : Screw loosening remains a recurring challenge in implant-supported prostheses. This is a particular problem in the case of crown restorations cemented on implants. Especially when implant required non-axial angle during implantation. To stabilize prosthetic reconstruction it requires to tighten them without damaging implant-supported structure. Objective : This paper presents unique workflow between cone-beam computer tomography (CBCT), dental impression, 3D scan, three-dimensional (3D) segmentation and mixed reality visualization to plan and execute precise access openings for screw tightening in prosthetic implant-supported structure. Method : Patient underwent a CBCT scan which was processed in 3DSlicer software. Additionally dental impression was done with 3D. Merged data resulted in obtaining high quality 3D model. To visualize the ideal trajectory for screw access virtual tube was created on it. Final step was to implement model in mixed reality application using Unity for Meta Quest 3 headset. Clinician evaluated model in mixed reality, verified optimal drilling angle and subsequently performed clinical procedure. This case report was prepared and reported in accordance with CARE guidelines and completed CARE checklist. Result : Mixed reality application displaying high detailed model allowed clinician to clearly understand accurate spatial angle to drill holes in prosthesis. All screws requiring tightened were done which restored stability of implant-supported structure. Conclusion : Utilize Mixed Reality technology to display 3D models based on CBCT scan can effectively help clinicians for planning complex prosthetic interventions when implants are done with not common technique. This can improve precision and confidence during procedure which also reduce damage on prosthetic structure.