Objective 3D-printed aligners (DPAs) are a promising alternative to thermoformed aligners (TFAs), but variations in post-curing procedures may affect their biocompatibility. This study evaluated the in-vitro cytotoxicity of DPAs under different post-curing conditions and compared them with TFAs. Materials DPAs were printed using 3D-print TC-85DAC resin (Graphy, Seoul, Korea) and post-cured under various conditions. In Experiment 1, two post-curing conditions were tested on animal cells and compared: 14 min with nitrogen (P1A) using Tera Harz Cure (THC2, Graphy, Seoul, Korea), and 30 min on each side (P1B) using Form Cure machine (FormLabs Inc, Somerville, USA). In Experiment 2, three post-curing conditions using the same curing machine (THC2) were tested on human cells: with Nitrogen for 14 minutes (P2A), without Nitrogen for 14 minutes (P2B), without Nitrogen for 30 minutes (P2C). In the Experiment 3, three aligner materials were compared: 3D- printed resin (TC-85DAC, Graphy, Korea), thermoformed Smart Track (Align Technology, USA), and thermoformed TruGEN (Spark, Ormco, USA). Aligners were cut into 2 × 2 mm specimens, sterilized at 121°C, and incubated in in 96-well plates containing DMEM at 37°C for 7 and 14 days. The cells viability of MC3T3E-1 mouse pre-osteoblasts and primary human dental bud stem cells (DBSCs) was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Optical density values obtained from animal and human cell cultures were normalized to untreated controls, summarized as means and statistically analyzed (a=0.05). Results After 7 and 14 days, the cell viability of P1B was significantly reduced compared to P1A (P<0.001). Overall, P1B post-curing exhibited moderate cytotoxicity, while P1A post- polymerisation was highly biocompatible. A significant reduction in cell survival was observed in the P2B and P2C post-curing groups compared to P2A (P<0.05). At 7 days, P2A showed higher cell survival than P2B and P2C, though differences were not significant. At 14 days, P2A exhibited the highest viability among post-curing groups, with significant differences compared to P2B and P2C (P<0.05). From 7 to 14 days, P2B and P2C showed significant viability decreases (P<0.01), whereas P2A showed stable results. Overall, P2A demonstrated the highest cytocompatibility across timepoints. The comparison of cytotoxicity between DPA and TFA did not reveal any significant differences with both SmartTrack and TruGen. Conclusion The 3D-printing of aligners may represent a viable biocompatible alternative to the conventional thermoforming process. However, the different post-curing conditions may significantly influence the cytotoxicity of DPA, and the use of nitrogen in the post-curing process may significantly reduce DPA cytotoxicity over time.
Biocompatibility of New Orthodontic Materials / Campobasso, Alessandra. - (2024).
Biocompatibility of New Orthodontic Materials
Campobasso, Alessandra
2024-01-01
Abstract
Objective 3D-printed aligners (DPAs) are a promising alternative to thermoformed aligners (TFAs), but variations in post-curing procedures may affect their biocompatibility. This study evaluated the in-vitro cytotoxicity of DPAs under different post-curing conditions and compared them with TFAs. Materials DPAs were printed using 3D-print TC-85DAC resin (Graphy, Seoul, Korea) and post-cured under various conditions. In Experiment 1, two post-curing conditions were tested on animal cells and compared: 14 min with nitrogen (P1A) using Tera Harz Cure (THC2, Graphy, Seoul, Korea), and 30 min on each side (P1B) using Form Cure machine (FormLabs Inc, Somerville, USA). In Experiment 2, three post-curing conditions using the same curing machine (THC2) were tested on human cells: with Nitrogen for 14 minutes (P2A), without Nitrogen for 14 minutes (P2B), without Nitrogen for 30 minutes (P2C). In the Experiment 3, three aligner materials were compared: 3D- printed resin (TC-85DAC, Graphy, Korea), thermoformed Smart Track (Align Technology, USA), and thermoformed TruGEN (Spark, Ormco, USA). Aligners were cut into 2 × 2 mm specimens, sterilized at 121°C, and incubated in in 96-well plates containing DMEM at 37°C for 7 and 14 days. The cells viability of MC3T3E-1 mouse pre-osteoblasts and primary human dental bud stem cells (DBSCs) was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Optical density values obtained from animal and human cell cultures were normalized to untreated controls, summarized as means and statistically analyzed (a=0.05). Results After 7 and 14 days, the cell viability of P1B was significantly reduced compared to P1A (P<0.001). Overall, P1B post-curing exhibited moderate cytotoxicity, while P1A post- polymerisation was highly biocompatible. A significant reduction in cell survival was observed in the P2B and P2C post-curing groups compared to P2A (P<0.05). At 7 days, P2A showed higher cell survival than P2B and P2C, though differences were not significant. At 14 days, P2A exhibited the highest viability among post-curing groups, with significant differences compared to P2B and P2C (P<0.05). From 7 to 14 days, P2B and P2C showed significant viability decreases (P<0.01), whereas P2A showed stable results. Overall, P2A demonstrated the highest cytocompatibility across timepoints. The comparison of cytotoxicity between DPA and TFA did not reveal any significant differences with both SmartTrack and TruGen. Conclusion The 3D-printing of aligners may represent a viable biocompatible alternative to the conventional thermoforming process. However, the different post-curing conditions may significantly influence the cytotoxicity of DPA, and the use of nitrogen in the post-curing process may significantly reduce DPA cytotoxicity over time.File | Dimensione | Formato | |
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