Roughness and wettability of aligner materials

Orthodontic aligners are fabricated from thermoplastic materials, whose surface properties influence plaque accumulation. While prior research has shown that surface roughness and wettability affect bacterial adhesion, the specific impact of these properties in aligner materials remains unclear. Existing studies have focused on general dental polymers rather than aligner-specific materials. This gap motivated an investigation into how surface energy and roughness parameters of commercial aligner materials vary. No prior work had resolved whether thermoforming affects these properties. The study aimed to clarify whether differences in surface characteristics exist among materials and whether these could predict plaque retention. This work builds on prior findings but narrows the focus to orthodontic aligner materials. By examining both as-received and thermoformed states, the research addresses a gap in understanding how processing affects material behavior. The findings may help clinicians choose materials that reduce plaque accumulation risks.

The study aimed to compare surface roughness and wettability of four common thermoplastic aligner materials. It sought to determine whether these properties differ between as-received and thermoformed states. The specific problem addressed is the lack of data linking material surface properties to plaque retention in orthodontic aligners. The motivation stems from clinical concerns about bacterial adhesion to aligner surfaces. By quantifying roughness and surface energy parameters, the study aimed to identify materials with potentially lower plaque-retaining properties. The research focused on four commercially available materials: CAM, COP, DUR, and ERK. It also aimed to assess how thermoforming impacts these properties. The ultimate goal was to provide data to guide material selection in orthodontic practice.

The study tested four thermoplastic materials: CAM, COP, DUR, and ERK. Five disk samples from each material were prepared and analyzed. Surface roughness was measured using reflected light microscopy and optical profilometry. Parameters included Sa, Sz, Sq, Sdr, Sc, and Sv. Contact angle measurements were performed using a Zisman series of liquids. This allowed calculation of critical surface tension (γ_C), total work of adhesion (W^A), and polar (W^P) and dispersion (W^D) components. Thermoformed disks were prepared using a dental stone model to simulate clinical conditions. Statistical analysis included one-way ANOVA and Tukey post-hoc tests. All measurements were repeated five times per sample to ensure reliability. The methods combined both qualitative and quantitative approaches to capture surface texture and wettability differences.

As-received materials showed smooth surfaces under microscopy and profilometry. After thermoforming, surfaces became significantly rougher, though differences within groups remained insignificant. CAM had the lowest γ_C and highest W^A, W^P, and W^D. ERK displayed the highest γ_C but lower W^A. COP and DUR fell in an intermediate range for γ_C. W^A differences between COP and DUR were significant, mainly due to lower W^P in COP. Surface roughness parameters did not differ significantly between as-received and thermoformed states. These findings suggest that surface energy, not roughness, may influence plaque retention. Variations in γ_C, W^A, W^P, and W^D could predict material performance in clinical settings.

The authors suggest that differences in surface energy parameters may influence plaque retention in orthodontic aligners. They propose that γ_C, W^A, W^P, and W^D are more relevant than roughness for predicting bacterial adhesion. Their findings indicate that CAM and ERK have distinct surface energy profiles. COP and DUR showed intermediate energy characteristics. The lack of roughness differences between as-received and thermoformed states suggests that processing does not significantly alter texture. The authors propose that clinicians may consider surface energy when selecting aligner materials. They suggest that materials with lower γ_C and higher W^A may retain less plaque. These conclusions are based on the observed variations in surface energy parameters among the tested materials.