Comparing stainless steel, resin, rigid silicone, and adaptive silicone SH 6/7 sickle scalers in a standardized simulation.
Musculoskeletal disorders (MSDs) are a leading occupational issue in dental hygiene. Because hand scaling can drive fatigue and strain, this 2025 study evaluated how four SH 6/7 sickle scaler handles affect muscle work and post-instrumentation fatigue:contentReference[oaicite:0]{index=0}.
Key findings (TL;DR)
- Adaptive silicone handle showed the most favorable ergonomic performance overall:contentReference[oaicite:1]{index=1}.
- It produced significantly less muscle work than any of the three rigid handles (all p<0.0001):contentReference[oaicite:2]{index=2}.
- Fatigue ratings (VAS): significantly lower in the fingers versus all rigid handles, and in the thumb versus the rigid resin handle:contentReference[oaicite:3]{index=3}.
- Tester comments: “don’t have to grip as hard,” “more secure in my hand,” and “more comfortable” for the adaptive silicone handle:contentReference[oaicite:4]{index=4}.
What the researchers did
- Participants: 11 right-handed dental hygiene students (24–40 years):contentReference[oaicite:5]{index=5}.
- Task: 1-minute scaling per study arm on typodonts; SH 6/7 blades used for all handles; order randomized:contentReference[oaicite:6]{index=6}.
- Handles tested: rigid stainless steel, rigid resin, rigid silicone, and adaptive silicone (flexible core that conforms to the hand):contentReference[oaicite:7]{index=7}.
- Measures: VAS fatigue (thumb, fingers, palm, wrist) and sEMG from APB, FDI, FPL, EDC; standardized processing and analysis (GLM with Tukey post-hoc):contentReference[oaicite:8]{index=8}.
See Figure 2 for electrode placement and Figure 3–4 for fatigue and muscle-work charts in the paper.:contentReference[oaicite:9]{index=9}
Results that matter
1) Fatigue (VAS)
The adaptive silicone handle reduced perceived fatigue, reaching statistical significance in the fingers vs. all rigid handles and in the thumb vs. rigid resin:contentReference[oaicite:10]{index=10}.
2) Muscle work (sEMG)
Average muscle work was lowest with the adaptive silicone handle; pairwise differences were large and highly significant:
- Adaptive silicone vs. rigid stainless steel: −59.8 (AUC units), p<0.0001:contentReference[oaicite:11]{index=11}
- Adaptive silicone vs. rigid resin: −39.3, p<0.0001:contentReference[oaicite:12]{index=12}
- Adaptive silicone vs. rigid silicone: −20.2, p<0.0001:contentReference[oaicite:13]{index=13}
3) What clinicians said
- Rigid stainless steel: familiar, but tiring:contentReference[oaicite:14]{index=14}
- Rigid resin: light, but grip felt too hard:contentReference[oaicite:15]{index=15}
- Rigid silicone: softer feel, still rigid:contentReference[oaicite:16]{index=16}
- Adaptive silicone: feels lighter, less gripping force, more secure and comfortable:contentReference[oaicite:17]{index=17}
Why adaptive handles help
Handles that conform to the user’s hand can increase contact area and distribute pressure more evenly, which reduces pinch force and localized strain—explaining the lower muscle work and finger/thumb fatigue observed with the adaptive silicone design:contentReference[oaicite:18]{index=18}.
Limitations
- Small sample (n=11) and short task duration per arm:contentReference[oaicite:19]{index=19}.
- Student testers only; results may differ in experienced clinicians:contentReference[oaicite:20]{index=20}.
Bottom line
Handle design matters. For SH 6/7 sickle scalers, an adaptive silicone handle can meaningfully reduce both muscle work and fatigue compared with rigid stainless steel, resin, and rigid silicone designs:contentReference[oaicite:21]{index=21}.
Source: Davis A, Zozaya O, Bratt L, Shayo K. Effect of Handle Design and Material on the Ergonomic Performance of a Dental Sickle Scaler. J Oral Med Dent Res. 2025;6(1):87. Open access under CC BY-NC-ND 4.0:contentReference[oaicite:22]{index=22}.