Stereolithography (SLA), a form of 3D printing additive manufacturing, finds extensive use across various industries, notably in biomedical applications [1]. SLA based additive manufacturing involves vat photopolymerization technology to create solid objects by the process of photopolymerization of vat of liquid resin using laser. Vat photopolymerization is superior to other additive manufacturing (AM) technologies, for example selective laser sintering (SLS) and fused deposition modeling (FDM) due to its ability to fabricate intricate complex parts with high speed, spatial resolution and precision [2]. Presently, SLA and FDM are engaged in direct competition, primarily due to the initial high cost of resin and the increasing number of SLA providers, resulting in a decline in resin prices. As 3D printing doesn't need cutting or grinding metal, it provides a great deal of design and geometric freedom to the manufacturers to meet industrial requirements beyond the conventional fabrication methods [3]. Besides offering flexibility in shapes, additive manufacturing methods can integrate various materials in one item, enabling users to switch materials during printing for intricate combinations, resulting in customized mechanical and design attributes not achievable through traditional manufacturing methods. It has transitioned from being solely a prototyping tool to being employed in the production of consumer-ready goods [4]. Companies are increasingly drawn to 3D printed products due to their minimized energy consumption and waste generation [5]. In the realm of biomedicine, 3D printed technology has been found to be the most effective owing to the possibility of fabrication of patient specific customized products. In dentistry, the use of AM techniques has been generally accepted for sophisticated treatment planning, making orthodontic and bite splints, and making surgical drill guides. It is essential that surgical guidelines for oral implantology are made precisely [6].
Various parameters have been explored to observe the impact of printing pathways on mechanical properties. Increasing layer thickness reduces printing time but deteriorates the surface finish [7, 8]. In SLA, post-curing creates inter-layer linkages resulting in a smooth surface finish without visible layer interfaces [9]. The strength of the material is also influenced by changes in the infill parameter. Many scholars have investigated how different build settings affect the mechanical properties of polymer materials using various 3D printing techniques [10]. Song et al. [11] inspected the mechanical response of unidirectional 3D-printed Polylactic acid (PLA) by conducting a series of tensile, compressive, and flexural tests. Their study revealed significant anisotropy in mechanical properties due to the printing orientation and layer bonding. Key findings included the higher strength and stiffness along the printing direction and the notable impact of layer adhesion on the material's overall mechanical performance. Wang et al. [12] focused on enhancing PLA’s impact strength in fused layer modeling (FLM) through material modifications. They experimented with various additives and processing conditions to improve the toughness of PLA. The study found that specific additives significantly increased the impact resistance of PLA without compromising its printability, demonstrating a viable method to produce more durable 3D-printed PLA parts. Cantrell et al. [13] experimentally characterized the mechanical properties of 3D-printed parts made-up of Polycarbonate and Acrylonitrile butadiene styrene (ABS). They performed compressive, tensile, and flexural tests to assess the materials' strength, stiffness, and failure modes. The study exposed that polycarbonate generally exhibited superior mechanical properties compared to ABS, and that both materials' properties were significantly affected by layer orientation and infill density. Ankouhi et al. [14] conducted mechanical characterization and failure analysis of 3D-printed ABS, focusing on the effects of printing orientation and layer thickness. Through tensile and impact testing, they found that thinner layers and optimized orientation significantly enhanced the mechanical performance and failure resistance of ABS parts. The study concluded that careful selection of printing parameters is crucial for maximizing the strength and durability of 3D-printed components. Torrado and Roberson [15] analyzed the failure and anisotropy of tensile test specimens with varying print raster patterns and geometries. Their evaluation, involving tensile testing, indicated that both specimen geometry and raster pattern significantly influence the mechanical properties and failure behavior. The study highlighted that certain print patterns and geometries can mitigate anisotropy, leading to more uniform strength and improved performance in 3D-printed parts. Durgun and Ertan [16] conducted an experimental investigation of the Fused Deposition Modeling (FDM) technique to enhance mechanical properties while considering production cost. Through systematic experimentation and analysis, they identified optimal process parameters that improved mechanical strength without significantly increasing production expenses. Their findings contribute valuable insights into optimizing FDM for cost-effective yet high-performance 3D printing applications. Sood et al. [17, 18] conducted a comprehensive investigation into the mechanical properties of FDM parts. The study involved a parametric appraisal to understand how different printing parameters affect mechanical properties. They performed experimental investigations and developed empirical models specifically aimed at enhancing compressive strength through optimized FDM processing. Lee et al. [19] measured the anisotropic compressive strength of AM parts. Through their study, they assessed how the orientation of the printed layers affects the compressive strength of the parts. Vega et al. [20] investigated the influence of layer orientation on both microstructure and mechanical properties of a polymer. Through their study, they examined how different printing orientations affect the material's mechanical performance and internal structure. This research contributes to a deeper understanding of how printing parameters impact the final properties of 3D-printed parts, providing valuable insights for optimizing printing processes and material selection. Rao et al. [21] explored the influence of conventional drilling and additive fabrication techniques on the tensile properties of 3D-printed ONYX/CGF composites. Their study investigated how different methods of creating holes within the composites affect their mechanical behavior. By comparing conventionally drilled holes to additively fabricated ones, the research provides insights into optimizing manufacturing processes for composite materials, offering potential enhancements in strength and performance. It likely includes experimental comparisons of tensile strength and modulus between specimens with these different hole fabrication methods, aiming to optimize composite performance. Compared to traditional fabrication techniques, SLA-printed surgical guides are purported to enhance the precision of implant positioning. Even with drill guides, achieving a fully predictable implant position isn't guaranteed. Surgical guidelines printed via SLA exhibited discrepancies of up to 13% from the intended design. These errors primarily stem from data manipulation by the operator or irregular fitting of the surgical guide. Notably, the latter issue may indicate inaccuracies in the fabrication process of SLA-printed surgical guides [22].The precision of SLA printing can be influenced by both the printing process itself and the characteristics of the photosensitive resins employed. While SLA printing typically involves preset parameters like printing speed, cured line width, energy distribution, and cure depth, certain preprocessing settings such as configuring supporting structures, positioning objects on the build platform, and determining object orientation must be adjusted. Additionally, operators have control over post-processing steps like washing, cleaning, and final polymerization, all of which can impact the precision and mechanical properties of the produced parts. Variations in both pre- and post-processing procedures may affect the accuracy and mechanical characteristics of the final product [23]. The stability of surgical drill guides during use is crucial to prevent fracture and bending. Studies have shown that different printing directions can influence the mechanical properties of various SLA materials. A new class I biocompatible resin designed for surgical guide production has recently been introduced and utilized in clinical settings for tasks such as implant placement and sinus grafting [24]. However, for this particular resin type, the manufacturer provides specifications for flexural properties but lacks information regarding the effects of printing process parameters on these properties.
From the literature review, it can be summarized that there is currently no existing research that explores the utilization of this specific resin in SLA manufacturing to analyze how processing settings impact accuracy and mechanical properties. Therefore, this study aims to investigate the effects of print orientation, part placement on the build platform, and post-curing processes on the mechanical properties of SLA-produced items. Tensile, flexural, fracture and impact test were conducted for mechanical analysis. Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA) tests were conducted for analyzing the thermal stability and thermo-mechanical behavior of resin respectively. For identifying chemical compound, FT-IR test of resin was also performed. The information gathered can guide dental professionals in optimizing printing parameters and design considerations for specific dental applications, ensuring the fabrication of high-quality and durable dental prosthetics and devices.