What type of study is this?

This is a In Vitro Study study.

September 10, 2025Open Access

Comparative In Vitro Analysis of Composite Resins Used in Clear Aligner Attachments

Key Points

AC demonstrated superior mechanical properties compared to CF, leading to a more durable attachment—this is crucial for effective treatment outcomes.
DSC showed significant thermal differences between AC and CF, with AC exhibiting higher thermal stability, reflecting its capacity for better performance under stress.
Tribological analysis indicated that AC had a greater friction coefficient than CF, showcasing its better wear performance which is vital for patient comfort during therapy.
Surface roughness tests showed that AC maintained a smoother surface after wear, which is essential for reducing plaque accumulation and improving hygiene.

Abstract

Background: Attachments are essential components in clear aligner therapy, enhancing retention and improving the predictability of tooth movements. Mechanical and wear properties of the composite resins used for attachment reproduction are critical to maintaining their integrity and shape over time. This study aimed to evaluate and compare the mechanical properties, thermal behavior, and wear performance of the hybrid composite Aligner Connect (AC) and the flowable resin (Connect Flow, CF). Methods: Twenty samples (ten AC and ten CF) were reproduced. All specimens underwent differential scanning calorimetry (DSC), combustion analysis, flat instrumented indentation, compression stress relaxation tests, and tribological analysis. A 3D wear profile reconstruction was performed to assess wear surfaces. Results: DSC and combustion analyses revealed distinct thermal transitions, with CF showing significantly lower Tg values (103.8 °C/81.4 °C) than AC (110.8 °C/89.6 °C) and lower residual mass after combustion (23% vs. 61%), reflecting reduced filler content and greater polymer mobility. AC exhibited superior mechanical properties, with higher maximum load (585.9 ± 22.36 N) and elastic modulus (231.5 ± 9.1 MPa) than CF (290.2 ± 5.52 N; 156 ± 10.5 MPa). Stress relaxation decrease was less pronounced in AC (18 ± 4%) than in CF (20 ± 4%). AC also showed a significantly higher friction coefficient (0.62 ± 0.060) than CF (0.55 ± 0.095), along with greater wear volume (0.012 ± 0.0055 mm3 vs. 0.0070 ± 0.0083 mm3) and maximum depth (36.88 ± 3.642 µm vs. 17.91 ± 3.387 µm). Surface roughness before wear was higher for AC (Ra, 0.577 ± 0.035 µm; Rt, 4.369 ± 0.521 µm) than for CF (Ra, 0.337 ± 0.070 µm; Rt, 2.862 ± 0.549 µm). After wear tests, roughness values converged (Ra, 0.247 ± 0.036 µm for AC; Ra, 0.236 ± 0.019 µm for CF) indicating smoothened and similar surfaces for both composites. Conclusions: The hybrid nanocomposite demonstrated greater properties in terms of stiffness, load-bearing capacity, and structural integrity when compared with flowable resin. Its use may ensure more durable attachment integrity and improved aligner–tooth interface performance over time.

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Cite This Study

Gazzani et al. (Wed,) studied this question.

synapsesocial.com/papers/68c1bb6a54b1d3bfb60ed6fd https://doi.org/https://doi.org/10.3390/app15158698

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