Purpose: This study aimed to investigate gingival thickness variations regarding age, gender, and sites where mini-screws are frequently applied and to guide mini-screw size selection. Materials and Methods: In our study, gingival thickness measurements were performed by a transgingival probing method in 224 patients who presented for examination to the Department of Orthodontics, Faculty of Dentistry, XXXX University. Fifty-six females and 56 males aged 14-20 and 21-27 years were enrolled in the study. In each individual, measurements were made from the mucogingival junction at the interdental area in the buccal mandibular and buccal maxillary regions, whereas at the interdental area within 4 mm and 8 mm distance from the gingival crest in the palatinal maxilla. Results: Comparisons between genders indicated that gingival thickness in the buccal region of the maxilla was statistically significantly greater in males than in females (p