Scanning electron microscopy analysis of aligner fitting on anchorage attachments.

Orthodontic aligners rely on precise fitting to anchorage attachments for effective tooth movement. Prior research has shown that variations in aligner material and attachment resin can influence fit accuracy. However, no prior work had resolved how different aligner brands and resin types interact in real-world fitting scenarios. Established knowledge includes the general role of attachments in enhancing aligner control. This gap motivated a detailed SEM-based analysis of fitting precision across multiple aligner types and resin materials. No prior work had resolved how upper versus lower attachments differ in fitting behavior. The study aimed to clarify these uncertainties using a controlled experimental setup. No prior work had resolved the comparative performance of Invisalign, CA Clear Aligner, and F22 in this context. The need for precise fitting remains a central challenge in aligner-based orthodontics.

The study aimed to compare how three orthodontic aligner systems fit onto anchorage attachments, using scanning electron microscopy. A second objective was to assess how the type of resin used for attachments affects aligner fitting. The specific problem addressed is the lack of direct comparisons between aligner brands and resin materials in fitting accuracy. Motivation stems from the need to improve treatment predictability through better attachment design. The study focused on upper and lower arch differences in fitting behavior. The goal was to identify whether certain aligner systems or resin types consistently provide better fit. No prior work had resolved how attachment resin influences aligner performance. The findings could inform material selection for attachment fabrication.

The researchers created six resin casts from a patient’s STL files and bonded rectangular attachments to each. Upper attachments were made with conventional bulk-fill resin, while lower ones used flowable resin. Each cast received a passive aligner from one of three brands: Invisalign, CA Clear Aligner, or F22. Aligners were sectioned buccolingually for SEM imaging. Microphotographs captured fitting details at the attachment interface. Micrometric measurements quantified the fit between aligners and attachments. The SEM provided high-resolution images for precise analysis. The study design allowed for controlled comparisons between aligner types and resin materials.

Invisalign showed significantly better upper arch fitting than F22 (P=0.009), but no significant difference was found between Invisalign and CA Clear Aligner. Upper attachments made with bulk-fill resin had significantly better fitting than those with flowable resin (P=0.034). F22 outperformed both Invisalign and CA Clear Aligner in lower arch fitting (P=0.011 and P=0.008, respectively). No significant difference was found between CA Clear Aligner and F22 in the upper arch. The lower arch fitting was consistently worse than the upper arch for all aligner types. The resin type had a measurable impact on fitting accuracy. These findings suggest that material choice influences attachment performance. The results highlight variability in brand performance depending on arch location.

The authors concluded that Invisalign, CA Clear Aligner, and F22 have comparable fitting performance on anchorage attachments. Conventional bulk-fill resin provides better fitting than flowable resin in upper arches. No significant difference was found between the three aligner brands in the upper arch. F22 showed better lower arch fitting than the other two brands. The study suggests that attachment resin type influences fitting accuracy. The findings support the use of bulk-fill resin for upper attachments. The authors propose that aligner brand choice may depend on arch-specific needs. These results may guide clinicians in material and aligner selection.