Aim: In clinical practice, a proper diagnosis of the periodontal biotype is considered important with respect to the decision-making. Periodontal biotype and the gingival thickness is considered as an important factor, which affects the success of periodontal and orthodontic treatment results. Long-term studies that evaluated the association between the gingival recession and orthodontic treatment were concluded that gingival recession was more frequent in individuals who have been treated orthodontically and mandibular incisors were more prone to gingival recession than the other teeth. The aim of this study was to assess the prevalence of the gingival biotypes in a group of patients and to evaluate if the gingival biotypes were related with the different types of Angle’s classification of malocclusion. Methods: This a longitudinal cohort study was conducted on 74 patients (35 males, 38 females, mean age 14.7 years old). Gingival thickness was assessed clinically, on each patient by a single calibrated examiner. Intra- examiner agreement was verified by calculating Cohen’s k coefficient. The kappa coefficients were calculated for the measurements obtained at each different examination. Gingival biotypes were assessed with the evaluation on the translucence of a periodontal probe through the gingival margin of the tooth during the probing, at the mid facial aspect of both maxillary central, lateral incisors and canine on each patient, Angle’s classification of malocclusion was also recorded. Dental occlusion was clinically assessed using Angle’s classification of malocclusion. In order to assess the association between gender, gingival biotype and Angle’s classification of malocclusion (categorical variables) χ2 (Chi square) test was used. For continuous variables, Student’s t-test was performed in order to compare male and female subjects and, therefore, thin and thick gingival biotype. Results: The prevalence in the whole sample of thin gingival biotype was 42.3% and thick gingival biotype was 52.4%. The frequency of female gender with thin gingival biotype was significantly less respect to male patients (41.2% and 52.4%, respectively) while the frequency of thick gingival biotype was higher in the female respect to male patients (54.5% and 46.3%, respectively) (χ2=1.337, p=0.245). The mean age of patients with thin gingival type (14.6±0.5 years) was statistically, but not clinically, significantly higher respect to the patients with thick gingival type (14.1±0.7 years), p=0.026. There was not a significant association between type of malocclusion and gingival biotype (p=0.143) and there was a prevalence of thick gingival biotype in patient with class II malocclusion and a slight prevalence of thin gingival biotype in patient with class I malocclusion. Conclusion: Patient age, health status of periodontal tissues, duration of treatment, the amount and type of tooth movement, the width of keratinized gingiva and gingival thickness are considered risk factors of gingival recession that can be seen especially in mandibular incisors area depending on orthodontic treatment. The present longitudinal cohort study showed that that female subjects presented a higher prevalence of thin gingival biotype respect to male subjects and that no relationship was found between gingival biotypes and malocclusion, based on Angle’s classification. Further studies are needed, in a large scale, to confirm this important relationship between gingival biotype, skeletal profile and facial type.