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Thesis
Influence of print direction on accuracy and mechanical properties of 3 D printing resin
University of Iowa
Master of Science (MS), University of Iowa
Summer 2023
DOI: 10.25820/etd.006970
Abstract
Objective: To assess the influence of print direction on accuracy and mechanical properties of 3D printable resin-based composites by estimating the length, width, and height dimensions, determination of flexural strength and modulus, wear properties, and fracture resistance.
Method: Permanent Crown Resin (Formlabs) and Temporary CB Resin (Formlabs) were used to print specimens in (0o, 45o, and 90o) directions using Formlabs Form 3 Low Force Stereolithographic (LFS) desktop printer. Ninety-six specimens (2mmx2xxmm25mm) were printed to assess dimensional accuracy and flexural strength. seventy-two cylindrical-shaped specimens (6mmx3mm) were for localized wear testing. For fracture resistance, ninety-six premolar crowns and abutments were printed using temporary CB and permanent crown resin while premolar die abutments were printed with Vero White resin (Stratasys) using Stratasys J750 polyjet 3D printer. A digital micrometer (ABSOLUTE Digimatic, Mitutoyo) was used to measure specimens’ length, width, and height (n=16). Flexural strength testing was conducted (n=16) in three-point bending following ISO 4049. While localized wear testing (n=12) was stimulated using 400,000 cycles in a Lenifelder-Suzuki machine. Ninety-six premolar crowns were subjected to fracture resistance testing (n=16) with a crosshead speed of 0.5 mm/min, and a force of 10kN using a Zwick Roel universal testing machine. And qualitative visual assessment of fracture patterns was done with scanning electron microscopy. Statistical analysis included two-sample t-test, one- and two-way ANOVA, post hoc Tukey’s test Wilcoxon rank-sum test, Kruskal-Wallis test, and Friedman’s two-way nonparametric ANOVA when appropriate (alpha=0.05).
Results: Mean length and width dimensions were significantly higher in the 0◦ direction for permanent resin compared to temporary resin (p<0.001). For both materials, 0◦ and 45◦ showed better accuracy than 90◦. Permanent resins showed significantly higher flexural strength than temporary resins in all print directions(P<0.001). Mean maximum depth and volume loss of permanent resin was significantly lower than that of temporary resin (p<0.05) after wear challenge, 45◦ showed more wear pattern for both resins. 45◦ also showed significantly higher mean fracture resistance than 0◦ and 90◦. Failure mode III and mode I were associated with permanent and temporary respectively.
Conclusion: Accuracy and mechanical properties were influenced by a change in the print direction and orientation in the permanent and temporary crown resin with 45◦ showing favorable results for the parameters tested. Significant interactions between resin type, and print direction on accuracy and mechanical properties were noted.
Details
- Title: Subtitle
- Influence of print direction on accuracy and mechanical properties of 3 D printing resin
- Creators
- Josephine Itakpe
- Contributors
- Akimasa Tsujimoto (Advisor)Erica Teixeira (Committee Member)Fang Qian (Committee Member)Mahrous Ahmed (Committee Member)Cristina De Mattos Pimenta Vidal (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Oral Science
- Date degree season
- Summer 2023
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.006970
- Number of pages
- xii, 110 pages
- Copyright
- Copyright 2023 Josephine Itakpe
- Language
- English
- Date submitted
- 07/07/2023
- Description illustrations
- illustrations, tables, graphs
- Description bibliographic
- Includes bibliographical references (pages 82-88).
- Public Abstract (ETD)
- The use of 3-D resins as useful alternatives for dental restorations has been limited due to concerns regarding their accuracy and material strength. The focus of 3 D research is to create adaptations by changing the printing parameters such as print direction to improve the properties of these materials since they are considered anisotropic. But it is unclear to what extent these adaptations can improve the material strength.
This study aims to determine if a change in print direction during fabrication can improve the accuracy and strength of these materials. We used flexural strength, elastic modulus, fracture resistance, and resistance to wear of two experimental which were printed using 0,90 and -45 degrees to assess the mechanical properties. For accuracy, we measured all our printed specimens and compared them with our reference digital design for any dimensional variations. Following this, we used scanning electron microscopy to qualitatively analyze how these materials break under high chewing forces. Statistical analysis revealed that accuracy was affected by print direction. We also observed that samples printed with 45 degrees print direction had superior fracture resistance when compared to the 0- and 90-degrees directions, but they had poor resistance to wear.
Within the limitations of our study, we observed that 45 degrees printed specimen showed good accuracy and mechanical properties except for the poor resistance to wear and we concluded that our tested variables were affected by print direction.
- Academic Unit
- Oral Pathology, Radiology and Medicine
- Record Identifier
- 9984454742502771
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