Chlorhexidine-assisted cleaning increases staining of PETG clear aligners exposed to common beverages: an in vitro study

Background Clear aligner therapy is increasingly popular due to its esthetic appearance, comfort, and removability. Successful outcomes rely on patient compliance, requiring 20–22 hours of daily wear. Exposure to dietary chromogens and inadequate cleaning can cause discoloration, compromising appliance transparency and hygiene. Since commercial cleaning systems are often inaccessible or costly in some settings, clinicians may suggest affordable alternatives, such as brushing or using common antibacterial agents like chlorhexidine (CHX) mouthwash. This study aimed to evaluate the esthetic impact of CHX-assisted cleaning by investigating the color stability of two polyethylene terephthalate glycol (PETG) aligner materials (Taglus Premium and Taglus Standard) during exposure to common staining beverages. Methods In this in vitro experimental study, 240 thermoformed specimens (120 per material) were fabricated. Samples were assigned to four environments (tea, coffee, cola, and dry control) and two daily cleaning protocols: brushing under running water or brushing following a one-minute immersion in 0.2% CHX mouthwash. Color measurements were recorded using a spectrophotometer at baseline (T0), after 7 hours of staining without cleaning (T1), and after 14 days of staining combined with daily cleaning (T2). Results No baseline color differences were observed. At T1, Taglus Premium exhibited significantly greater discoloration than Taglus Standard in tea and control groups (p < 0.05), with tea producing the highest ΔE. At T2, both materials exhibited marked cumulative discoloration. Staining solution, cleaning protocol, and their interaction significantly influenced ΔE (p < 0.01). Tea induced the greatest color change across both materials, while coffee and cola produced smaller effects. CHX-assisted cleaning resulted in significantly higher discoloration than brushing alone. After 14 days, the highest ΔE values occurred in the tea + CHX groups. Conclusions Color stability of PETG aligners was significantly affected by staining environment, cleaning protocol, exposure duration, and material type. Tea was identified as the most potent chromogenic agent, and the use of 0.2% CHX mouthwash markedly exacerbated staining. Clinicians should advise patients to remove aligners during consumption of chromogenic beverages and exercise caution in recommending CHX as a routine cleaning method. Further in vivo research is warranted to confirm these findings and provide evidence-based hygiene recommendations. Trial registration Clinical trial number: Not applicable.