Reading an aligner-cleaning study
Invisalign® Cleaning Crystals: colour and roughness
One trial reported less aligner discoloration with Efferdent® than with Cleaning Crystals, while its separate overall surface-roughness comparison favoured Cleaning Crystals. These findings concern different properties. Some comparisons by study period and upper or lower aligner also reversed the overall roughness ordering.
In this partial crossover trial at one clinic, 20 people contributed 240 Invisalign® aligners. Each person tried two of five cleaning agents, in an uneven order with no washout period between them. Possible carryover from an earlier agent limits how these findings can be applied.
The useful question is what each measurement tells you. Follow the two findings together before treating either as an answer about your own appliance.
Two measurements, two questions
- Colour change
- The researchers measured colour on the aligner before and after use with a spectrophotometer, an instrument for measuring colour. This was aligner discoloration, not the shade of the person's teeth.
- Average surface roughness, Ra
- Ra was the study's numerical average surface-roughness measure, recorded in micrometres on sampled aligner material. Unused aligners provided a roughness control. This measurement described the sampled surface, not how white teeth looked.
A colour result can describe a difference in aligner appearance. It does not supply the separate Ra measurement. Keeping the property beside the product name makes the comparison more informative.
How the two reported comparisons fit together
Original trial · DOI 10.1186/s12903-025-06928-w
Discoloration
The article reports less aligner discoloration with Efferdent® than with Invisalign® Cleaning Crystals in its group-level colour comparison.
This is the reported ordering for that appearance measurement.
Overall measured roughness
The separate overall comparison across cleaning agents reports lower Ra with Cleaning Crystals than with Efferdent®.
This is a reported numerical surface comparison. Lower Ra does not by itself establish a healthier, safer or better-fitting aligner.
Keep the study conditions with those findings
This was a trial at one clinic: 20 people contributed 240 Invisalign® aligners. Each person tried two of five cleaning agents. The order of agents was not fully balanced, and there was no washout period to help separate an earlier agent's effects from the next study period. Possible carryover therefore remained a limitation.
The reported comparisons also depended on study period and whether upper or lower aligners were compared. For roughness, the article reports some upper-aligner and first-period comparisons in which Efferdent® had lower Ra than Cleaning Crystals. Those conditional comparisons reverse the overall ordering above.
The overall finding is therefore not the finding for every condition.
What this tells you
The colour result favours Efferdent® for the reported discoloration comparison. The separate overall Ra result favours Cleaning Crystals for the measured surface property, with a different ordering in some study conditions. Both statements concern different questions: appearance cannot stand in for roughness.
The two measurements describe different properties, so the study does not identify one product that is better in every respect. The comparison does not choose a cleaner or routine for you.
Whose aligners were studied?
The trial took place at Bezmialem Vakıf University's orthodontic clinic, with recruitment and follow-up from October 2021 to June 2022. The authors describe 23 people assessed or enrolled over the study, exclusions and replacements, and 20 people in the final analysis. Participants were selected using oral-health, general-health and study-adherence criteria.
Several aligners came from each person. The researchers used statistical models that accounted for repeated observations; 240 aligners were not 240 independent people. Eight participants contributed to each cleaning agent, four in each study period.
Each person tried only two agents, so comparisons involving other agents were between different people. The partial crossover, uneven order of agents and possible period effects limit how widely the findings can be applied. The authors also could not verify whether everyone followed the study's storage directions consistently.
This comparison does not establish results for children, retainers, other brands or other materials.
Keep the finding separate from your directions
Colour change and Ra do not measure microbial disinfection, tooth whitening, fit or clinical safety. Words such as “Anti-Bacterial” in a tested product's name do not turn those into measured outcomes.
A study comparison and your current appliance directions have different roles. If you are receiving care, use your treating team's supplied contact route to clarify a product or care instruction for your own plan.
For the separate explanation of tooth-surface care, tray cleaning and dated manufacturer statements, read aligner care and follow-up.
Care that continues beyond the appliance
SMILE-FX® provides full-service digital orthodontics with a clear-aligner focus. Board-certified orthodontists see patients at follow-ups. Standard smartphone monitoring supports communication and clinical progress review; provider-support contact access is distinct from an immediate reply.
Explore the complete care model and individual arrangements, including planning, fabrication, continuing review, retention and the separately prescribed whitening goal.
Considering orthodontic care?
You can request a free in-person consultation at the SMILE-FX® studio in Miramar. The team confirms visit arrangements and the individual assessment scope. A request does not confirm an appointment or case acceptance.
Source and adaptation
Banu Kılıç, Şeymanur Canpolat and Merve Öztürk. Comparative evaluation of the effect of different cleaning agents on colour and surface roughness of Invisalign® clear aligners: a cross-over randomized controlled trial. BMC Oral Health 25:1745, published 4 November 2025. Original article · DOI 10.1186/s12903-025-06928-w.
© The Author(s) 2025, corrected publication 2025. This explanation is adapted under the Creative Commons Attribution 4.0 International licence. Changes: shortened and reorganized findings and limitations, plain-language measurement descriptions and a comparison of the two results. Reference does not imply endorsement.
Invisalign® and Efferdent® are referenced product names; the respective owners retain their marks.
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