Jae-Heon Kim1, Moon-Young Kim2, Jonathan C Knowles3, Sunyoung Choi4, Hyejong Kang5, Sang-Hyun Park6, Sung-Min Park7, Hae-Won Kim8, Jong-Tae Park9, Jung-Hwan Lee10, Hae-Hyoung Lee11. 1. Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine Research Center, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea. Electronic address: wogjs199@naver.com. 2. Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Department of oral and maxillofacial surgery, College of Dentistry, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea. Electronic address: kmyomfs@dankook.ac.kr. 3. Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine Research Center, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; UCL Eastman-Korea Dental Medicine Innovation Centre, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Division of Biomaterials and Tissue Engineering, Eastman Dental Institute, University College London, London, UK; The Discoveries Centre for Regenerative and Precision Medicine, Eastman Dental Institute, University College London, London, UK. Electronic address: j.knowles@ucl.ac.uk. 4. Department of Prosthodontics, Sejong Dental Hospital, School of Dentistry, Dankook University, Sejong, Chungcheongnam-do, 30107, Republic of Korea. Electronic address: annejane@hanmail.net. 5. Department of Orthodontics, Sejong Dental Hospital, School of Dentistry, Dankook University, Sejong, Chungcheongnam-do 30107, Republic of Korea. Electronic address: hyejongk@dankook.ac.kr. 6. Osong Research Institute, TaeWoong Medical Co., Ltd, 55-7, Osongsaengmyeong 2-ro, Republic of Korea. Electronic address: shpark1@stent.net. 7. Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine Research Center, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea. Electronic address: hahatype12@naver.com. 8. Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine Research Center, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea. Electronic address: kimhw@dku.edu. 9. Department of Oral Anatomy, College of Dentistry, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea. Electronic address: jongta2@dankook.ac.kr. 10. Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Department of Nanobiomedical Science & BK21 PLUS NBM Global Research Center for Regenerative Medicine Research Center, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea. Electronic address: ducious@gmail.com. 11. Department of Biomaterials Science, College of Dentistry, Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea; Institute of Tissue Regeneration Engineering (ITREN), Dankook University, 119 Dandae-ro, Cheonan, Chungcheongnam-do 31116, Republic of Korea. Electronic address: haelee@dku.edu.
Abstract
OBJECTIVE: Titanium and its alloys are widely used for dental and medical biomaterials due to their excellent mechanical and biological advantages. After the introduction of direct laser metal sintering (DLMS) 3D printing technology and its use over conventional machine-cut processes, questions remain regarding whether 3D-printed titanium (alloy) devices have similar biological properties to machine-cut counterparts for dental applications. Thus, this work focuses on comparing the biological activities of machine-cut and 3D-printed specimens after optimizing the DLMS 3D-printing conditions in terms of the mechanophysical characteristics. METHODS: The DLMS 3D-printing (as a function of the laser spacing from 30-100μm) and post-surface treatment (as-given or sand-blasted) conditions were optimized using medical-grade Ti-6Al-4V powders in terms of the inner pore amount, mechanical properties, roughness and hydrophilicity. Then, the initial cell adhesion of the optimized DLMS 3D-printed Ti-6Al-4V specimen was compared with that of the machine-cut Ti-6Al-4V specimen against human dermal fibroblasts (hDFs) and mesenchymal stem cells (hMSCs), which are representative of direct-contact cell types of orofacial mucosa and bone, respectively. hMSC differentiation on the specimens was conducted for up to 21 days to measure the osteogenic gene expression and biomineralization. RESULTS: Laser spacings of 30-40μm had fewer inner defects and consequently a higher three-point flexural strength and elastic modulus compared to other larger laser spacings. Depending on the span width (0.3-1mm) in the lattice architecture, the elastic modulus of the 3D-printed cuboid specimen can be further controlled (up to ∼30 times). The sand-blasted specimens after 3D printing revealed lower surface roughness and higher hydrophilicity compared to the as-3D printed specimen, which were considered optimal conditions for biological study. Initial hDF and hMSC adhesion for 12 hr and hMSC differentiation on the surface were comparable between the sand-blasted 3D-printed and machine-cut specimens in terms of adherent cell numbers, vinculin intensity, osteogenic gene expression and biomineralization. SIGNIFICANCE: The optimized DLMS 3D-printed Ti-6Al-4V specimen had similar biological properties to those of the machine-cut counterpart, suggesting the potential usefulness of 3D printing technology for a wide range of dental applications.
OBJECTIVE: Titanium and its alloys are widely used for dental and medical biomaterials due to their excellent mechanical and biological advantages. After the introduction of direct laser metal sintering (DLMS) 3D printing technology and its use over conventional machine-cut processes, questions remain regarding whether 3D-printed titanium (alloy) devices have similar biological properties to machine-cut counterparts for dental applications. Thus, this work focuses on comparing the biological activities of machine-cut and 3D-printed specimens after optimizing the DLMS 3D-printing conditions in terms of the mechanophysical characteristics. METHODS: The DLMS 3D-printing (as a function of the laser spacing from 30-100μm) and post-surface treatment (as-given or sand-blasted) conditions were optimized using medical-grade Ti-6Al-4V powders in terms of the inner pore amount, mechanical properties, roughness and hydrophilicity. Then, the initial cell adhesion of the optimized DLMS 3D-printed Ti-6Al-4V specimen was compared with that of the machine-cut Ti-6Al-4V specimen against human dermal fibroblasts (hDFs) and mesenchymal stem cells (hMSCs), which are representative of direct-contact cell types of orofacial mucosa and bone, respectively. hMSC differentiation on the specimens was conducted for up to 21 days to measure the osteogenic gene expression and biomineralization. RESULTS: Laser spacings of 30-40μm had fewer inner defects and consequently a higher three-point flexural strength and elastic modulus compared to other larger laser spacings. Depending on the span width (0.3-1mm) in the lattice architecture, the elastic modulus of the 3D-printed cuboid specimen can be further controlled (up to ∼30 times). The sand-blasted specimens after 3D printing revealed lower surface roughness and higher hydrophilicity compared to the as-3D printed specimen, which were considered optimal conditions for biological study. Initial hDF and hMSC adhesion for 12 hr and hMSC differentiation on the surface were comparable between the sand-blasted 3D-printed and machine-cut specimens in terms of adherent cell numbers, vinculin intensity, osteogenic gene expression and biomineralization. SIGNIFICANCE: The optimized DLMS 3D-printed Ti-6Al-4V specimen had similar biological properties to those of the machine-cut counterpart, suggesting the potential usefulness of 3D printing technology for a wide range of dental applications.