Effect of a Helical Ultrasonic Scaler Tip on Dentin Surface Roughness

Objectives: To evaluate the effects of a novel helical ultrasonic scaler tip (HUST) on dentin surface roughness and compare its performance with a non-helical ultrasonic scaler tip (NHUST) and a conventional hand scaler (Gracey Curette, GC). The HUST was designed to minimize dentin damage while maintaining high efficiency in calculus removal. Materials and Methods: Standardized dentin blocks prepared from extracted human teeth were used to evaluate the effects of each instrument (HUST, NHUST, GC). Tip wear was assessed using scanning electron microscopy (SEM) after 0, 50, 100, 200, and 400 applications. Surface roughness was quantified by measuring the total height of the profile (Pt) using a non-contact surface profilometer based on Coherence Correlation Interferometry. Statistical analysis was performed using Shapiro–Wilk test, Kruskal–Wallis test, and Steel–Dwass post hoc analysis. Results: No visible wear was observed on either ultrasonic tip, even after 400 applications. Pt was significantly higher in the NHUST group (18.80 ± 6.21 µm) than in the HUST (10.26 ± 4.31 µm) and GC (6.05 ± 3.78 µm) groups (p < 0.01). No significant difference was observed between the HUST and GC groups. All experimental groups showed greater roughness than the polished control (3.29 ± 1.14 µm), but the HUST group exhibited significantly lower surface alteration than the NHUST group. Conclusions: The HUST demonstrated dentin surface preservation superior to that of the NHUST and comparable to hand instrumentation. Clinical Relevance The HUST may represent a promising option for subgingival scaling, with reduced dentin surface trauma while maintaining mechanical durability.