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Quality assurance of stereolithography based biocompatible materials for dental applications
Halmstad University, School of Business, Innovation and Sustainability.ORCID iD: 0000-0002-8364-202x
Halmstad University, School of Business, Innovation and Sustainability.ORCID iD: 0000-0002-2330-0597
Hallands Hospital, Halmstad, Sweden.
Hallands Hospital, Halmstad, Sweden.
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2023 (English)In: Surface Topography: Metrology and Properties, ISSN 2051-672X, Vol. 11, no 1, article id 014008Article in journal (Refereed) Published
Abstract [en]

Additive Manufacturing (AM) is increasingly being used in healthcare sectors for its potential to fabricate patient-specific customized implants, and specifically in dentistry, AM finds its applications in maxillofacial implants, dentures, and other prosthetic aids. However, in most applications, AM is largely being used for prototyping purposes. The full-scale realization of AM can only be achieved if the downsides of AM are addressed and resolved. Hence this paper focuses on providing a detailed analysis of surface quality, dimensional accuracy, and mechanical properties of the biocompatible material produced, using the Stereolithography (SLA) method for a dental application. For quality analysis, test artefacts were produced, and the quality was assessed before and after the sterilization process. The results suggest that micro-surface roughness essential for cell growth is similar for all build inclinations and well within the control limit required for effective bone regeneration. Multi-scale surface characterization revealed that the sterilization process involving heat can potentially alter the micro-roughness features of resin-based materials. The results from the dimensional analysis show that the SLA parts produced had negligible dimensional deviations from the CAD model to the printed parts and were unaffected by the sterilization process. The tensile test results suggest that the part orientation does not affect the tensile strength and that the sterilization process seems to have an insignificant effect on the tensile properties of the SLA parts. Furthermore, the results were validated by producing a membrane barrier for Guided Bone Regeneration (GBR). The validation results showed that excess resin entrapment was due to the geometrical design of the membrane barrier. In conclusion, this paper provides an overview of quality variations that can help in optimizing the AM and sterilization process to suit dental needs. © 2023 IOP Publishing Ltd.

Place, publisher, year, edition, pages
Bristol: Institute of Physics Publishing (IOPP), 2023. Vol. 11, no 1, article id 014008
Keywords [en]
additive manufacturing, autoclave sterilization process, dental application, dimensional accuracy, surface metrology, tensile properties, topography characterization
National Category
Probability Theory and Statistics
Identifiers
URN: urn:nbn:se:hh:diva-50251DOI: 10.1088/2051-672X/acbe54ISI: 000945276300001Scopus ID: 2-s2.0-85149878416OAI: oai:DiVA.org:hh-50251DiVA, id: diva2:1748969
Note

This research work is a joint effort from the researchers at Halmstad University and Maxillofacial doctors at the Region Halland hospital in Halmstad. The authors would like to acknowledge the contribution of other members who assisted in this project such as the staff/nurses in Region Halland hospital for sterilizing the samples and colleagues at Halmstad University in the Functional surfaces research group for their input.

Available from: 2023-04-05 Created: 2023-04-05 Last updated: 2026-02-10Bibliographically approved
In thesis
1. On Characterization and Optimization of Surface Topography in Additive Manufacturing Processes
Open this publication in new window or tab >>On Characterization and Optimization of Surface Topography in Additive Manufacturing Processes
2022 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With its ability to construct components through the layer-by-layer deposition of material, Additive Manufacturing (AM), more commonly known as "3D printing", has revolutionized the manufacturing industries. Not only can AM produce complex lightweight designs, but it can also streamline the supply chain, allowing businesses to more quickly and easily meet customer demand. Additionally, with the rising demand for low-volume customized products and sustainable production, manufacturers are increasingly compelled to adopt AM to remain competitive in the global economy. Despite its popularity, AM has several significant drawbacks, one of the most notable being its poor surface topography quality. Most product failures can be traced back to the initial surface conditions, making the surface texture a crucial factor in determining how well a product will perform. Hence, this thesis presents a study on the surface topography of various AM processes, mainly to understand the surface behavior in relation to the factors affecting it. Every manufacturing process, including AM, generates distinct surface features referred to as “footprints” or process signatures, which substantially affect the surface quality and function. These process signatures vary based on changes in AM processes and their process settings, materials, and geometrical design. The accuracy of identifying and analyzing these features becomes crucial in defining their relationship with manufacturing process variables. Usually, the best practice for defining surface quality is through parametric characterization, which provides a quantitative description of either the stochastic or deterministic nature of manufactured surfaces. However, the challenge with AM is that it generates surfaces that often contain both the aforementioned surface features, which make it particularly difficult to identify the manufacturing “footprints” through the parametric description. Therefore, the surface topography of AM may often require novel characterization methods to fully interpret the manufacturing process and thereby predict and optimize its product performance. The overall goal of this thesis is to provide an optimal approach toward the characterization of AM surfaces so that it gives a better understanding of the manufacturing process and also assists in process optimization to control the surface quality of the printed products. To realize this goal, the surface texture of AM processes was studied, particularly Material Extrusion (MEX), Vat Photopolymerization (VPP), and Powder Bed Fusion (PBF). These processes present topographical features that cover most of the surface scenarios in AM. Hence, to explain these varied surface features, a diverse range of surface characterization tools, such as Power Spectral Density (PSD), scale-sensitive fractal analysis, feature-based characterization, and quantitative characterization by both profile and areal surface texture parameters, were included in the analysis. Additionally, a methodology was developed using a statistical approach (linear multiple regression) and a combination of the above-mentioned characterization techniques to identify the most significant parameters for discriminating different surfaces. Finally, the knowledge gained through the above-mentioned measurements and analysis is put to use to optimize the AM process to achieve enhanced surface quality. The results suggest that the developed approaches can be used as a guideline for AM users who are looking to optimize the process for gaining better surface quality and component functionality, as it works effectively in finding the significant parameters representing the unique signatures of the manufacturing process.

Place, publisher, year, edition, pages
Gothenburg: Chalmers Univeristy of Technology, 2022. p. 93
Series
Thesis for the degree of Doctor of Philosophy, ISSN 0346-718X ; 5225
Keywords
additive manufacturing, vat-photopolymerization, fused deposition modeling, laser-based Powder bed fusion, surface metrology, power spectral density, scale-sensitive fractal analysis, featurebased characterization, profile parameters, areal surface texture parameters, and multiple regression.
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:hh:diva-57967 (URN)978-91-7905-759-6 (ISBN)
Public defence
2022-12-15, Virtual Development Laboratory (VDL), Chalmers Tvärgata 4C, Campus Johanneberg, Gothenburg, 10:15 (English)
Opponent
Supervisors
Available from: 2026-02-10 Created: 2025-12-03 Last updated: 2026-02-10Bibliographically approved

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Vedantha Krishna, AmoghReddy, Vijeth VenkataramRosén, Bengt Göran

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