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. 2025 Jul;37(7):1940-1948.
doi: 10.1111/jerd.13476. Epub 2025 Apr 3.

The Effect of Different Surface Treatments on the Roughness, Translucency, and Staining of 3D-Printed Occlusal Device Materials

Silvia Rojas Rueda  1 , Hanna Sepsick  2 , Mohammed Hammamy  1 , Amir H Nejat  3 , Edwin Kee  3 , Nathaniel C Lawson  4
Affiliations

The Effect of Different Surface Treatments on the Roughness, Translucency, and Staining of 3D-Printed Occlusal Device Materials

Silvia Rojas Rueda et al. J Esthet Restor Dent. 2025 Jul.

Abstract

Objectives: To compare surface treatments (as-printed, optical polish, resin-coated, polished) of two 3D-printed occlusal device materials (KeySplint Soft and NightGuard Flex 2) cured with or without glycerin for surface roughness, translucency, and coffee staining.

Materials and methods: Discs (2 mm thick) from two 3D-printed occlusal resins (KeySplint Soft and NightGuard Flex 2) were printed using a DLP 3D printer (SprintRay Pro 95), cleaned (ProWash S), and cured (ProCure 2) with or without glycerin. Some specimens were printed in an optical polish tank. Specimens were either as-printed, resin-coated, or polished. Reference milled (ProArt CAD Splint) and heat-cured (Excel Formula Heat Cure Denture Base Material) specimens were also prepared. Surface roughness was analyzed using a contact profilometer. Translucency was measured using a spectrophotometer. Staining was evaluated after 24 days in coffee at 37°C. Data were analyzed with ANOVA and Tukey post hoc tests.

Results: Surface treatments and glycerin curing showed significant differences (p < 0.01). Polishing and resin-coating produced the smoothest surfaces. Optical polish tanks improved smoothness. Polishing increased translucency. Glycerin curing reduced staining except in polished specimens. Milled materials stained less than 3D-printed materials.

Conclusions: Polishing and resin-coating optimized roughness and translucency. Polishing or curing glycerin optimized stain resistance.

Clinical significance: 3D-printed occlusal devices should have their external surfaces polished or resin-coated and receive a final cure in glycerin to prevent staining of their internal as-printed surface. Printing in a tank with an optical polish can help to improve the roughness and translucency of the internal surface of an occlusal device.

Keywords: 3D printing; NightGuard; splints; surface roughness; translucency.

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Conflict of interest statement

Dr. Lawson has received research grants and speaking honoraria from Dentsply Sirona and Ivoclar Vivadent. The other authors declare no conflicts of interest.

Figures

FIGURE 1
FIGURE 1
Study design.
FIGURE 2
FIGURE 2
KeySplint Soft roughness, translucency, and staining. Different lowercase letters represent significant differences between different surface treatments (comparisons only within glycerin curing group). Different uppercase letters represent significant differences between different glycerin curing protocols (comparisons only within surface treatment group).
FIGURE 3
FIGURE 3
NightGuard Flex roughness, translucency, and staining. Different lowercase letters represent significant differences between different surface treatments (comparisons only within glycerin curing group). Different uppercase letters represent significant differences between different glycerin curing protocols (comparisons only within surface treatment group).
FIGURE 4
FIGURE 4
Different occlusal device material roughness, translucency, and staining. Different lowercase letters represent significant differences between different materials.
FIGURE 5
FIGURE 5
Photograph of representative specimens of (top to bottom): KeySplint Soft unstained, KeySplint Soft stained, NightGuard Flex unstained, and NightGuard Flex stained after different surface treatments and curing protocols (left to right): As‐printed, optical polish, resin‐coated, polished, as‐printed with glycerin cure, optical polish with glycerin cure, resin‐coated with glycerin cure, and polished with glycerin cure.
FIGURE 6
FIGURE 6
Photograph of representative specimens of (left to right): Milled, heat‐cured, KeySplint Soft, and NightGuard Flex before (top row) and after (bottom row) staining.
FIGURE 7
FIGURE 7
SEM images of representative specimens of KeySplint Soft (left to right): As‐printed, optical polish, resin‐coated, and polished after curing in air (top row) or glycerin (bottom row).
FIGURE 8
FIGURE 8
SEM images of representative specimens of NightGuard Flex (left to right): As‐printed, optical polish, resin‐coated, and polished after curing in air (top row) or glycerin (bottom row).
See this image and copyright information in PMC

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