The effect of clear aligners on speech: a systematic review.

This systematic review evaluates the impact of clear aligners on speech in patients undergoing orthodontic treatment, analyzing seven studies involving 332 patients. The findings indicate that clear aligners, primarily Invisalign, can cause temporary speech difficulties affecting various phonemes—especially sibilants like /s/ and /z/—resulting in lisping, slurring, and articulation errors similar to those seen with fixed and lingual orthodontic appliances. Speech impairments generally resolve within 7 to 14 days, though some patients may take up to two months to adapt. Due to methodological limitations and risk of bias in the included studies, the overall quality of evidence is low, and further well-designed randomized trials are recommended; orthodontists are advised to counsel patients about potential transient speech alterations when considering clear aligner therapy.