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Background <p>Post-curing is a critical step in the fabrication of 3D-printed resin-based occlusal splints because it influences polymerization efficiency and final material properties. Atmospheric oxygen may inhibit free-radical polymerization at the resin surface, whereas nitrogen-assisted post-curing may reduce this effect.</p> Objectives <p>This in vitro study evaluated the effects of post-curing atmosphere and duration on the Vickers hardness and surface degree of conversion of a 3D-printed occlusal splint material.</p> Methods <p>Sixty disc-shaped specimens (10&#xa0;mm × 2&#xa0;mm) were fabricated from a commercially available 3D-printable occlusal splint resin in six separate printing builds, with 10 specimens produced per build. The six builds were randomly assigned, one per condition, to nitrogen-assisted or ambient-air post-curing for 5, 10, or 20&#xa0;min (<i>n</i> = 10 per condition). Surface degree of conversion was determined using attenuated total reflectance Fourier transform infrared spectroscopy, and surface hardness was measured using a Vickers microhardness tester. Data were analyzed using two-way analysis of variance and Bonferroni-adjusted pairwise comparisons (α = 0.05).</p> Results <p>Post-curing atmosphere, duration, and their interaction significantly affected both surface degree of conversion and Vickers hardness (<i>p</i> &lt; 0.001). Post-curing duration showed the strongest effect on both outcomes. The highest surface degree of conversion was observed in the 20-min nitrogen-assisted group (89.97 ± 2.38%), followed by the 20-min ambient-air group (84.44 ± 2.38%). Similarly, the highest Vickers hardness was recorded in the 20-min nitrogen-assisted group (20.97 ± 0.95), followed by the 20-min ambient-air group (18.42 ± 0.50). Nitrogen-assisted post-curing produced significantly higher surface DC values than ambient-air post-curing at all durations, whereas a significant atmosphere-related difference in VHN was observed only at 20&#xa0;min.</p> Conclusions <p>Post-curing duration was the strongest factor affecting both outcomes. Nitrogen-assisted post-curing increased surface DC at all tested durations but produced a significantly higher VHN than ambient-air post-curing only after 20&#xa0;min.</p>

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Effect of nitrogen-assisted and ambient-air post-curing protocols on surface hardness and degree of conversion of a 3D-printed occlusal splint material

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年8月4日

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  • Dalndushe Abdulai,
  • Raghib Suradi,
  • Mehran Moghbel,
  • Musab Qamheya,
  • Rafat Sasany

摘要

Background

Post-curing is a critical step in the fabrication of 3D-printed resin-based occlusal splints because it influences polymerization efficiency and final material properties. Atmospheric oxygen may inhibit free-radical polymerization at the resin surface, whereas nitrogen-assisted post-curing may reduce this effect.

Objectives

This in vitro study evaluated the effects of post-curing atmosphere and duration on the Vickers hardness and surface degree of conversion of a 3D-printed occlusal splint material.

Methods

Sixty disc-shaped specimens (10 mm × 2 mm) were fabricated from a commercially available 3D-printable occlusal splint resin in six separate printing builds, with 10 specimens produced per build. The six builds were randomly assigned, one per condition, to nitrogen-assisted or ambient-air post-curing for 5, 10, or 20 min (n = 10 per condition). Surface degree of conversion was determined using attenuated total reflectance Fourier transform infrared spectroscopy, and surface hardness was measured using a Vickers microhardness tester. Data were analyzed using two-way analysis of variance and Bonferroni-adjusted pairwise comparisons (α = 0.05).

Results

Post-curing atmosphere, duration, and their interaction significantly affected both surface degree of conversion and Vickers hardness (p < 0.001). Post-curing duration showed the strongest effect on both outcomes. The highest surface degree of conversion was observed in the 20-min nitrogen-assisted group (89.97 ± 2.38%), followed by the 20-min ambient-air group (84.44 ± 2.38%). Similarly, the highest Vickers hardness was recorded in the 20-min nitrogen-assisted group (20.97 ± 0.95), followed by the 20-min ambient-air group (18.42 ± 0.50). Nitrogen-assisted post-curing produced significantly higher surface DC values than ambient-air post-curing at all durations, whereas a significant atmosphere-related difference in VHN was observed only at 20 min.

Conclusions

Post-curing duration was the strongest factor affecting both outcomes. Nitrogen-assisted post-curing increased surface DC at all tested durations but produced a significantly higher VHN than ambient-air post-curing only after 20 min.