The impact of clear aligners therapy on dental caries: a systematic review

Dental caries is one of the most prevalent chronic conditions worldwide, significantly affecting public health and individual quality of life. Orthodontic treatments, particularly fixed appliances, may increase caries risk due to plaque retention and changes in the oral microbiota. Clear aligners, such as Invisalign®, represent a removable alternative that may facilitate oral hygiene and oral health. however, their impact on caries development remains a question to be investigate to understand the real opportunity in treating patients reducing the risk of caries.

To systematically evaluate the effect of clear aligner therapy on dental caries risk and cariological outcomes compared with fixed or traditional removable orthodontic appliances.

A systematic literature search was conducted up to June 2025 in PubMed/MEDLINE and Web of Science. Original clinical studies comparing clear aligners with fixed or traditional removable appliances were included according to predefined PICOS criteria. Outcomes of interest included DMFT scores, caries incidence, white spot lesions, enamel demineralization, and cariogenic bacterial profiles. Study selection and data extraction were performed independently by two reviewers, with disagreements resolved by a third reviewer. Risk of bias was assessed using ROBINS-I.

Three studies met the inclusion criteria (two case-control studies and one prospective cohort study). Two case-control studies reported a significantly greater increase in DMFT scores in patients treated with fixed appliances compared with clear aligners, while no significant differences in proximal caries incidence were observed. The cohort study found no significant differences in salivary levels of Streptococcus mutans and Lactobacilli between treatment modalities. Overall, no evidence of an increased caries risk associated with clear aligners was identified; however, the certainty of evidence was low.

Clear aligner therapy does not appear to be associated with a higher risk of dental caries compared with fixed or traditional removable appliances. Nevertheless, the limited number of studies and their methodological limitations highlight the need for well-designed prospective investigations with standardized caries outcomes.