ArticleClinical oral investigations2026
Color improvement and stability of orthodontic clear aligners following different cleaning protocols.
Article in Clinical oral investigations, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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5 authors.
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Abstract
objectivesTo evaluate the color improvement and stability of clear aligners after applying different hydrogen peroxide-containing and hydrogen peroxide-free cleaning protocols under simulated in-vitro conditions. MATERIALS AND
methodsClear aligners (Invisalign, Align Technology, San Jose, CA, USA) were immersed in coffee for 7 days (n = 24). They were then subjected to cleaning with four different chemical solutions: hydrogen peroxide-free – Group 1: Invisalign Cleaning Crystals (Align Technology, San Jose, CA, USA) and Group 2: Aktident gel (Rego X-ray GmbH, Augsburg, Germany); hydrogen peroxide-containing – Group 3: Corega Proguard (Stafford-Miller Limited, Waterford, Ireland) and Group 4: Steradent Blancheur Pro (Reckitt Benckiser Healthcare Limited, Hull, UK). Specimens were exposed to the different solutions according to manufacturer’s instructions, followed by a second 7-day discoloration cycle. Color (ΔE*, L*, a*, b*) were assessed at baseline, after a 7-day coffee exposure, after cleaning, and after the second discoloration using a spectrophotometer (Vita Easyshade Compact Advance, VITA Zahnfabrik, Bad Säckingen, Germany). Surface alterations were qualitatively analyzed using a scanning electron microscope (SEM).
resultsAfter the initial discoloration, ΔE values significantly increased in all groups and decreased following cleaning (p < 0.01), indicating partial color recovery. However, a subsequent restaining cycle caused a renewed increase in ΔE (p < 0.05). Although no significant intergroup differences were detected (p > 0.05), a significant intragroup difference between the first and second discoloration cycles was found in the peroxide-containing groups (Corega Proguard and Steradent Blancheur Pro) (p < 0.05). A negative correlation between pH and ΔE₂ was observed in the peroxide-free group (r = − 0.64, p < 0.05).
conclusionAlthough both hydrogen peroxide-containing and peroxide-free cleaning agents effectively reduce discoloration, variations in their pH and chemical composition influenced their efficacy. The differences in surface alterations among the cleaning agents highlight the need for a comprehensive assessment before recommending specific products to patients for aligner maintenance. CLINICAL RELEVANCE: Clinicians should consider the chemical composition and pH of cleaning agents when advising patients on aligner maintenance to avoid unwanted surface or color alterations.
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