Our study started from the hypothesis that the gingival volume growth associated with fixed orthodontic treatment appeared during the use of leveling and aligning archwires, without any inflammatory signs, as a result of the mechanical stress and periodontal remodeling during the orthodontic dental movement.We selected and included in the study 35 patients (13 females and 12 males) between 12 and 38 years of age, all suffering from gingival overgrowth, diagnosed during the active treatment with fixed orthodontic appliances (braces). For each patient, two tissue samples were taken: one in the early stages of the lesion, coinciding with the use of leveling and aligning archwires and another in the late stages of the lesion, coinciding with the use of finishing archwires. The samples were taken from the same site in the oral cavity. Out of 35 gingival biopsies taken from patients, 8 cases showed no significant changes in the gingiva, while in the remaining 27 cases, significant changes were found after the histopathological exam.Out of 27 gingival biopsies, 16 cases presented a significantly greater number of T cells. In addition, a greater number of B cells were observed in the granulation tissues than in the gingiva. The relative number of B cells (CD20), T cells and dendritic cells (CD8) has been expressed, both in the early and the late stages of the gingival lesions. Our results revealed that the proportion of T lymphocytes and dendritic cells was greater in the early stages rather than at the late stages. The B cells showed a higher count in the late stages.