# Analysis of 3D-Printed Zirconia Implant Overdenture Bars
###### Abstract  
Dental implant components are typically fabricated using subtractive manufacturing, often involving metal materials that can be costly, inefficient, and time-consuming. This study explores the use of additive manufacturing (AM) with zirconia for dental implant overdenture bars, focusing on mechanical performance, stress distribution, and fit. Solid and lattice-structured bars were designed in Fusion 360 and produced using LithaCon 210 3Y-TZP zirconia (Lithoz GmbH, Vienna, Austria) on a CeraFab 8500 printer. Post-processing included cleaning, debinding, and sintering. A 3D-printed denture was also fabricated to evaluate fit. Thermography and optical imaging were used to assess adaptation. Custom fixtures were developed for flexural testing, and fracture loads were recorded to calculate stress distribution using finite element analysis (ANSYS R2025). The FEA model assumed isotropic, homogeneous, linear-elastic material behavior. Bars were torqued to 15 Ncm on implant analogs. The average fracture loads were 1.2240 kN (solid, \(n=12\)) and 1.1132 kN (lattice, \(n=5\)), with corresponding stress values of 147 MPa and 143 MPa, respectively. No statistically significant difference was observed (\(p=0.578\); \(\alpha=0.05\)). The fracture occurred near high-stress regions at fixture support points. All bars demonstrated a clinically acceptable fit on the model; however, further validation and clinical evaluation are still needed. Additively manufactured zirconia bars, including lattice structures, show promise as alternatives to conventional superstructures, potentially offering reduced material use and faster production without compromising mechanical performance. d 2025 15 8751 28 July 2025 5 August 2025 19 June 2025 28 July 2025 5 August 2025 28 July 2025 5 August 2025 28 July 2025 5 August 2025 28 July 2025 5 August 2025 28 July 2025 5 August 2025 28 July 2025 28 July 2025 28 July 20  
that the implants withstand tensile forces and maintain the prosthesis in place [3]. Support implies that the implants also serve to resist the compressive forces generated by function [6]. With implant support, forces on the intraoral soft tissues are minimized, ultimately maximizing patient comfort [7]. Implant-retained prostheses provide some mitigation for the aforementioned issues [8]; however, an implant-supported prosthesis can provide a comprehensive solution to the problems related to complete edentulism [9]. Therefore, the ideal solution for an edentulous patient is an implant-supported approach [10]. Currently, there has been much progress with the fixed screw-retained hybrid denture. Although the aesthetics can be favorable, the product has limitations due to technical difficulty, cost, adjustability, and maintenance of oral hygiene [4]. The milled bar overdenture serves as an alternative approach, which provides the stability and retention of a fixed prosthesis and also offers the convenience and flexibility of a removable prosthesis [11]. With the milled bar overdenture, the bar remains attached to the implants, while the complete denture can be removed and reseated. This approach addresses some of the cost and hygiene concerns, but some technical difficulties remain [11]. A previous report showed a case report [12] illustrating a 12-year post-operative retrospective evaluation of a mandibular milled bar overdenture case, through clinical and radiological evaluation. Combining proper case selection and appropriate surgical and prosthodonic fundamentals, the treatment modality proves to be a predictable and successful option. Furthermore, the milled bar can be fabricated to compensate for misaligned implants while still supporting the denture and the patient's occlusion [13]. Milled bars are exclusively fabricated through a reductive manufacturing process, otherwise known as subtractive manufacturing [14], which represents a costly workflow and produces a high amount of waste [15].