This study aimed to evaluate the knowledge of oral hygienists working with orthodontic patients and cooperating with orthodontists. In February 2022, members of the Lithuanian oral hygienist society were invited to participate in a 37-question survey. The questionnaire was organized into eight sections representing specific information about the socio-demographic status of the respondents, cooperation with the orthodontist, individual oral hygiene products, patient education, professional oral hygiene, clinical situations, and knowledge. Two hundred and thirty fully completed questionnaires were returned. The mean of the dental hygienists' work experience was 5.28 years. 47% of the respondents answered that white spot lesions (WSL) occurred after the removal of braces, 48.7% answered that WSL did occur, but rarely, and 4.3% answered that they did not notice WSL. Work experience had no significant association (p=0,088) with WSL after braces removal. If a fixed retainer came off of several teeth, 1.7% of oral hygienists would do nothing, 2.2% would remove the wire, and 90.9% would send patients to their orthodontist. 32.2 % of oral hygienists who worked with an orthodontist were more likely to fix detached lingual retention wire (p=0.03), and 24.6% often referred to the orthodontist (p<0,001). Oral hygienists do not consider themselves capable of providing qualified assistance to orthodontic patients in the case of a treatment complication and therefore recommend them to seek the advice of an orthodontist. Oral hygienists state they lack knowledge about the particularity of orthodontic patients’ oral care and would be interested in lectures and training to extend this knowledge.