Comparative evaluation of the effect of different cleaning agents on colour and surface roughness of Invisalign clear aligners: a cross-over randomized controlled trial

Abstract

Background: Recent advancements in orthodontics have led to the widespread use of clear aligners, appreciated for their aesthetic and comfort advantages. However, standardized cleaning instructions remain undefined, and maintaining the surface integrity of aligners is critical for treatment efficacy and patient satisfaction. Although several studies have evaluated the effects of cleaning agents, comprehensive clinical evidence regarding their impact on the colour stability and surface roughness of Invisalign aligners is still lacking. This study aims to address this gap by comparing the effects of five commonly used cleaning agents on these key properties. Objectives: To assess the influence of various cleaning agents on both the colour and surface roughness of clear aligners. Materials and methods: This randomized crossover clinical trial included 23 participants with good oral hygiene, each requiring more than 12 aligners. Participants were randomly assigned to use two different cleaning agents in two consecutive treatment phases. The agents tested were: (1) Invisalign Cleaning Crystals (Align Technology, USA), (2) Efferdent Anti-Bacterial Denture Cleanser (Prestige Brands, USA), (3) Sensodyne Rapid Relief toothpaste (GlaxoSmithKline, UK), (4) Signal White Now Whitening Toothpaste (Unilever, USA), and (5) colourant-free clear soap (La Petit Marseillaise, France). Colour measurements (ΔE) were obtained using a spectrophotometer based on the CIE Lab* system, and surface roughness was evaluated with an optical profilometer. Bonferroni-corrected post hoc pairwise comparisons were conducted using Jamovi version 2.6.26. Results: Colourant-free clear soap caused the least colour change, while the Cleaning Crystals and Whitening Toothpaste showed the highest. Control (unused) aligners had greater surface roughness than cleaned aligners. Among cleaning agents, the Cleaning Crystals group exhibited significantly higher roughness than most others (p < 0.05). Conclusions: Cleaning agents influence the aesthetic and physical properties of aligners to varying degrees. Colourant-free clear soap demonstrated minimal impact on both colour and surface integrity and may be recommended as a safe and inexpensive option for daily aligner care. Trial registration: ClinicalTrials.gov Identifier: NCT05213650. Registered 17 January 2022. Retrospectively registered. This randomized controlled trial adheres to the CONSORT 2010 guidelines for reporting.