The aim of this study was to investigate the role of periodontal biotype in the development of gingival recession in patients who have undergone orthodontic treatment. A total of 60 mandibular incisors were analyzed. The qualitative assessment of periodontal biotype was performed with the use of a new biotype probe. A strong correlation was found between thin biotype and proinclination in terms of recession depth and keratinized tissue width. Patients with thin periodontal biotype are more prone to gingival margin instability, irrespective of the type of orthodontic movements. Thin periodontal biotype and proinclination orthodontic movement were related to loss of keratinized tissue width.