Effect of Nitrogen Gas Post-Curing and Printer Type on the Mechanical Properties of 3D-Printed Hard Occlusal Splint Material

Abstract

Although three-dimensional (3D) printing is clinically convenient to fabricate occlusal splints, it is still unclear how the post-curing method and the printer type can affect 3D-printed splints. This study aimed to evaluate the effect of stroboscopic post-curing at a nitrogen gas (N2) atmosphere versus post-curing in an air atmosphere, as well as the printer type (liquid crystal display (LCD) and digital light processing (DLP)) on the mechanical properties of a 3D-printed hard-type occlusal splint material. Flexural strength, flexural modulus, Vickers hardness number (VHN), fracture toughness, degree of double bond conversion (DC), 3D microlayer structure, water sorption, and water solubility were evaluated. The post-curing method significantly affected all evaluated properties except fracture toughness and 3D microlayer structure, while the printer type significantly affected all evaluated properties except flexural strength and flexural modulus. VHN and DC were significantly higher, and the smoother surface was noticeably obtained when printed by LCD printer and post-cured at an N2 atmosphere. The current results suggested that the post-curing method and the printer type would play a role in the mechanical properties of the evaluated material and that the combination of post-curing at an N2 atmosphere and LCD printer could enhance its mechanical properties and surface smoothness.

Effect of 3D Printer Type and Use of Protection Gas during Post-Curing on Some Physical Properties of Soft Occlusal Splint Material

“…Finally, in accordance with the same manner as the first drying procedure, the second drying procedure was continued until a stable weight (WT 3 ) of each specimen was acquired. W SP and W SL were calculated in percentages (%) using the following equations [ 19 , 45 , 46 ]: W SP = [(WT 2 − WT 3 )/WT 1 ] × 100 and W SL = [(WT 1 − WT 3 )/WT 1 ] × 100 where WT 1 is the initial weight of the specimen after storing it in a desiccator for 24 h in milligrams (mg); WT 2 is the weight of the specimen after water immersion for 30 days in milligrams (mg); and WT 3 is the stable weight of the specimen after the second drying cycle in milligrams (mg).…”

“…Recently, digital technology has played an important role in various dental fields. The three-dimensional (3D) printing method is rapidly becoming more common in dental appliance fabrications, including occlusal splints [ 18 , 19 ]. This method provides 3D objects built by a layer-by-layer replication with two-dimensional (2D) data acquired with computer-aided designing (CAD) and computer-aided manufacturing (CAM) systems [ 20 , 21 , 22 , 23 ].…”

“…Reymus et al reported that the post-curing methods affected the degree of conversion of 3D-printed interim prostheses, and stroboscopic post-curing in a nitrogen gas (N 2 ) atmosphere resulted in the highest degree of conversion [ 41 ]. Although a few studies have investigated the effect of the post-curing method on the mechanical properties of 3D-printed materials used for HSs [ 18 , 19 ], there is no report documenting the effect of post-curing on the mechanical properties of 3D-printed materials used for SSs.…”

Integrated manufacturing of direct 3D-printed clear aligners

“…This is followed by support removal and post-production curing with Cure M (Graphy, Seoul, Korea). The nitrogen generation curing unit has been utilized (28) and recommended to enhance the physical properties of the resin material by providing an inert environment, thereby preventing the formation of oxygen inhibition layer (37). THC 2 UV Curing system (Graphy Inc., Seoul, Korea) is a known representation of this category.…”

Effect of Surface Polishing on Physical Properties of an Occlusal Splint Material for Additive Manufacturing under Protection Gas Post-Curing Condition

“…Thanks to the increased light intensity, DLP printers can produce items more effectively, leading to the widespread development of dental materials for DLP-based stereolithography printing systems [ 17 , 18 ]. On the other hand, previous studies reported that LCD printers could provide objects with a smoother surface and a higher degree of conversion than DLP printers [ 19 , 20 ]. Although LCD printers might have several advantages, only a few studies have been performed on objects printed using LCD printers.…”