Related Experiment Video
Updated: Oct 26, 2026
Roughness Impact of Piezoelectric Dental Scaler on Two Distinct Flowable Composite Filling Materials
Published on: January 10, 2025
Optimizing light-curing protocols for clear aligner attachments: A comparison of bulk-fill and conventional resin
Narudol Treethanya1, Nuntinee Nanthavanich Saengfai1, Choltacha Harnirattisai2
1Department of Orthodontics, Faculty of Dentistry, Mahidol University, Bangkok, Thailand.
Background/Purpose:
The durability of clear aligner attachments is closely related to the polymerization and surface hardness of resin composites, which may be affected by extended light-curing distance during clinical procedures. This study aimed to evaluate the effects of different light-curing times at a 10 mm distance on the surface hardness and polymerization efficiency of conventional and bulk-fill resin composites.
Materials And Methods:
A total of 120 disk-shaped specimens (5 mm diameter, 2 mm thickness) were fabricated from six resin composites (two conventional and four bulk-fill). Specimens were light-cured for 20, 30, or 40 s using a low-intensity LED curing unit positioned 10 mm from the surface. Knoop microhardness numbers (KHNs) were measured on top and bottom surfaces after 24-h storage. The Knoop hardness ratio (%KHR) was calculated to assess depth of cure. Statistical analysis was performed using one-way ANOVA and independent t-tests (α = 0.05).
Results:
Increasing curing time significantly improved surface hardness and %KHR across all materials. Bulk-fill composites achieved the clinically acceptable 80% KHR threshold after 30 s, whereas conventional composites did not reach this level even at 40 s. No significant differences were observed between polystyrene (PS) and polyurethane (PU) template groups.
Conclusion:
A curing time of 30 s is sufficient for bulk-fill composites, while conventional composites require at least 40 s to achieve adequate polymerization under a 10 mm curing distance.