A Novel Computational Approach to CAD-Driven Biomechanical Analysis of 3D-Printed Dental Crowns Ruaa Rafil Waheeb 0 Ehsan Sabah Al-Ameen 0 1Mechanical Engineering Department, College of Engineering, Mustansiriyah University , Baghdad , Iraq 60 66

Stereolithography (SLA) resin 3D printing technology has changed many aspects of dental crown fabrication. The current work focuses on the finite element analysis study of mechanical behavior in under-axial loading conditions and quantifies Von Mises stresses in a SLA resin 3D printed crown. The results illustrated severe stress concentrations at the tips of the cusps with peak Von Mises stress around 136.3 MPa and maximum deformation around 0.02653 mm. The results showed that SLA resin crowns had higher levels of stress (75.0 MPa) compared to zirconia (65.0 MPa) and ceramic (70.0 MPa) crowns, indicating that the danger of failure under the influence of stressful factors is greater for this type of crown material. Still, SLA resin crowns showed lower deformation than zirconia (0.030 mm) and ceramic (0.035 mm). However, the need for shape optimization and improvement in material to increase the lifetime of SLA resin crowns was shown. However, there is a need for further research to match their performance to that of conventional materials. The future line of work should consider the development of new resin formulations that would better mechanical properties and the optimization of printing parameters to reduce stress and deformation in 3D-printed crowns.

 eol>Forecasted Economics Artificial Neural Networks Open Government Data Business Dynamics 1. Introduction

shown both materials to have a similar set of mechanical properties and the data satisfied [ 8, 12, 13, 14 ].

Prosthodontics, as a branch of dentistry, has experienced This means that the process of additive manufactura sea change with the assimilation of additive manu- ing can indeed be carried out for dental materials. Their facturing technologies, more commonly described as applications in dentistry have, therefore, advanced the 3D printing [ 1 ]. Wide applications benefit from addi- ways and means in prosthesis manufacture. Revilla-León tive manufacturing, including the communication sector and Özcan (2018) [15] in their study provide a compre[ 2, 3, 4, 5, 6 ]. These have brought a revolution in the fab- hensive overview of various 3D printing technologies rication of dental prostheses [ 7 ]. SLA resin 3D printing used in prosthodontics with their advantages and limitais one of the best technologies in producing functional tions. They underscore the potential of the technologies and esthetical dental crowns due to its very high level for enhanced precision and eficiency in the production of accuracy and smooth finish [ 8 ]. The high degree of of dental restorations. The mechanical properties of 3Dcustomization that 3D printing allows entails the produc- printed dental materials have been widely studied [16]. tion of dental restoration on a need-to basis. However, The oral environment provides a complex biomechanunderstanding the mechanical behavior of 3D-printed ical milieu with forces exerted on dental restorations. crowns under physiological loading is an essential aspect The value of the results of these studies is immense in in ensuring durability and clinical eficacy [ 7, 9, 8, 10 ] predicting clinical performance [17, 18, 19] as well as and quality [ 11 ]. Tahayeri et al. [12] in the study compar- reliability of these prostheses [20, 21]. Finite element ative analysis carried out between 3D-printed and con- analysis is a very strong non-invasive tool that helps to ventionally cured provisional crown materials displayed understand the mechanical behavior of dental structures within-materials comparable mechanical properties, re- and restorations [ 22, 23, 24 ]. The adoption of 3D printing spectively, that suggest the potential viability of additive in dentistry has been extensively studied, with a focus manufacturing within dental prosthetics. The introduc- on both the mechanical and biological properties of the tion of such technologies into dentistry has revolution- materials used. For instance, Atria et al [ 25 ] evaluated ized the methodologies used in fabricating prosthetics. the mechanical properties of various 3D-printed resins The 3D-printed provisional crown materials compared to for provisional dental restorations, finding that the exthe traditionally cured provisional crown materials have perimental Permanent Bridge (PB) resin demonstrated superior mechanical properties compared to other commercially available resins. The use of high-fidelity FEA for diferent fields [ 26, 27, 28, 29 ], specific in the bio mechanics material like dental prostheses is still an emergused in conventional prosthodontics. The unique mi- adult human molars, as reported by [ 30 ] as shown in crostructure of the printed resins and associated material Figure (1). properties call for a rethink of established biomechanical principles in crown design and manufacture. Previous studies have shown that stress distribution can vary significantly with diferent cusp angles in dental crowns [ 30 ]. This study employs finite element analysis (FEA) to investigate the mechanical behaviour of SLA resin 3Dprinted dental crowns under vertical loading conditions.

Achour et al. [ 31 ] studied FEA applications in the realm of dental implant research. It was determined that the tool is helpful in optimizing implant design as well as predicting its clinical performance. However, a significant shortage of works notes stress analysis of 3D-printed dental crowns through high-fidelity FEA models. Porojan and Topală [ 32 ] used the finite element method to study the failure mechanism of monolithic posterior aesthetic crowns; needful material choice and designs that would minimize stress concentrations were being discussed. Yoon et al. [ 33 ] further emphasized that crowns made from materials with higher elastic moduli, such as ceramics, were more efective in reducing stress on tooth structures. The convergence of additive manufacturing and FEA has opened new avenues for optimizing dental prosthetics, as discussed by [ 34 ], who explored the efects of diferent materials and designs on stress distribution Figure 1: Crown implement geometry in dental restorations. This paper tries to fill this gap by running advanced finite element high-fidelity models to The material properties used in the FEA model were detail the stress analysis in SLA resin 3D-printed den- based on a photopolymerizable resin specifically detal crown structures. In this study, the various loading signed for 3D printing of dental prostheses (NextDent scenarios have been applied using the Abaqus software C&B, 3D Systems). The key mechanical properties, as package for making judgments on the distribution of reported by the manufacturer and verified through instresses and deformation patterns in 3D-printed crowns. dependent testing, as reported from the previous study This paper gives new perspectives on the mechanical [35] where the behavior is like the composite material behavior of the specificities and functioning of the char- and has the elastic properties [36, 37]. acteristics of SLA resin crown by means of better design and fabrication techniques that provide better clinical 2.2. Finite Element Model Development results. It presents a comprehensive FEA study on SLA resin 3D printed dental crowns under normal loading The 3D model was imported into Abaqus CAE (Dassault conditions to provide insights into their mechanical be- Systèmes) for mesh generation and analysis. A tetrahavior. But as per this research, the SLA resin crowns hedral mesh was generated, consisting total number of can have some prospects in dental restorations, but in element 25570 linear tetrahedral elements of type C3D4 many aspects, they are behind the materials like zirconia as shown in the Figure (2). A mesh convergence study and ceramic. was conducted to ensure result accuracy while maintaining computational eficiency [ 23, 24 ], while an interesting improvement can be obtained by using neural approaches 2. Materials and Methods [38, 39]. Boundary conditions were applied to simulate the crown cemented to an idealized tooth preparation. 2.1. Crown Design and Material The interface between the crown and the tooth preparaProperties tion was modeled as a perfectly bonded connection [40].

The base of the tooth preparation was fixed in all degrees of freedom to simulate the constraints provided by the surrounding bone structure.

A three-dimensional model of a mandibular first molar crown was created using computer-aided design (CAD) software. The crown geometry was based on average anatomical measurements derived from a sample of 50 2.2.1. Loading Conditions The distinct loading scenarios were simulated to repre

sent a range of physiological and parafunctional forces, vertical load: A total force of 600 N was applied uniformly across the occlusal surface as shown in Figure (3), simulating normal mastication forces [ 33 ].

2.2.2. Analysis Parameters

The analysis was conducted using Abaqus/Standard, employing a static, linear elastic model. The von Mises stress criterion was used as the primary metric for evaluating stress distribution within the crown. Additional output variables included maximum principal stress, minimum principal stress, and total deformation.

 3. Results and Discussion

3.1. Stress Distribution Patterns

The finite element analysis (FEA) conducted under verti

cal loading conditions revealed distinct stress distribution patterns in the 3D-printed dental crown. Utilizing the von Mises stress criterion [41, 42], the analysis identiifed areas of high stress concentration, primarily at the cusp tips and the central fossa region of the crown. • Stress Concentrations: Under a vertical load of 600 N, stress was predominantly concentrated at the mesiobuccal cusp tip. The maximum von Mises stress recorded was approximately 136.3 MPa as shown in Figure (4). This high-stress concentration at the cusp tips indicates that these areas are critical points that bear the highest loads during normal mastication, making them susceptible to potential stress-induced failures.

The stress contour plots visually demonstrate the regions where the material is most likely to experience failure, emphasizing the importance of these findings in optimizing the design of dental crowns to enhance their durability. 3.2. Deformation Analysis The deformation analysis provided additional insights into the structural integrity of the 3D-printed dental crown under the applied load. The results indicated that the deformation patterns closely followed the stress distribution, with the highest deformation observed at the same critical regions identified in the stress analysis. The deformation distribution under a vertical load scenario shows that the highest deformation occurs at the cusp tips, particularly the mesio-buccal cusp tip, and the central fossa. Maximum Deformation, vertical load scenario resulted in a maximum deformation value of 0.02653 mm as shown in Figure (5).

This value is within the acceptable range for dental restorations, indicating that the crown can withstand functional loads while maintaining its structural integrity.

 4. Discussion

analysis as illustrated in Figure (6) showed that the SLA resin crowns have elevated stress concentrations, espeThe current study was aimed at conducting finite element cially at the cusp tips, compared to zirconia and ceramic. analysis to examine the mechanical behavior of SLA resin The maximum registered stress for SLA resin was 136.3 3D-printed dental crowns under a vertical loading con- MPa, as opposed to 65.0 MPa for zirconia and 70.0 MPa for dition. Important results can be derived by this means ceramic. These results indicated that SLA resin crowns regarding the patterns of stress distribution and deforma- might have a higher tendency for specific areas of stresstion, which could possibly be predicted due to this new related failures, and therefore the optimization of design manufacturing way, in order to make possible further im- was required in order to ensure their durability. provements on such a material. Comparison with Past Deformation Analysis: From Figure (7) can be obStudies: In this section, the current results are compared served that the deformation study revealed that the maxin detail with the findings from past studies for diferent imum deformation of SLA resin crowns was 0.02653 mm, crown materials such as zirconia and ceramic. The quan- lower than that found for zirconia at 0.030 mm, followed tities of importance for the stress and deformation from by ceramic at 0.035 mm. This indicates that stress concenthese comparisons are listed in Table 1. trations are higher and deformation is lower in loading Implications of Stress Results: The von Mises stress conditions for SLA resin crowns within clinically accept

 5. Conclusion

This study presents a comprehensive finite element analysis (FEA) of SLA resin 3D-printed dental crowns under vertical loading conditions, revealing key insights into their mechanical behavior. The analysis indicates that while SLA resin crowns show promising potential for 60–66

Key Findings Higher stress at cusp tips, moderate deformation Lower stress concentration, high durability Balanced stress distribution, suitable for crowns Reference This Study Yoon et al. [ 33 ] Porojan Topală, [ 32 ] and dental restorations, there are notable areas for improvement, especially when compared to traditional materials like zirconia and ceramic.

• Important Findings: 1. Stress Distribution: From the von Mises stress analysis, it has been revealed that increased levels of stresses occurred at the cusp tips in the SLA resin crowns, with a maximum of around 136.3 MPa. This is indeed much higher in comparison with those observed for zirconia and ceramic crowns, respectively, the value indicating a much higher susceptibility to stress-induced failures of the SLA resin crowns

2. Patterns of Deformation: The highest deformation that was recorded on SLA resin crowns was 0.02653 mm, which was just slightly lower when compared with that from both zirconia and ceramic crowns, again confirming the fact that SLA resin crowns can withstand the dynamic behavior of forces applied during normal functioning of the system.

• Future Research Directions , Future research should aim to: Explore New Materials: Investigate advanced photopolymerizable resins with superior mechanical properties to reduce stress and deformation. Optimize Printing Parameters: Study the efects of diferent printing parameters, such as layer thickness and orientation, on the mechanical properties of 3D-printed crowns. Conduct Long-term Clinical Studies: Perform long-term clinical trials to validate the in-vivo performance of SLA resin crowns and their suitability for permanent restorations. In conclusion, while SLA resin crowns ofer a viable solution for dental restorations, particularly for temporary and provisional applications, further optimization in design and material properties is essential. Continued research and development in additive manufacturing technologies will be crucial in advancing the clinical efectiveness and durability of 3D-printed dental prostheses.

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