Introduction: In the literature, the definition of gummy smile has been mostly based on vertical measurements of gum exposure. The objective of this work was to determine new diagnosis criteria of gummy smile based on the correlation between the clinical, occlusal and cephalometric parameters. Methods: An analytical cross-sectional multivariate study was performed on a sample of 110 patients randomly selected from the dento-facial orthopedics department at the dental faculty of Monastir with a medium age of 17.2 years. The patients selected had no orthodontic history. A total of 77 variables were analyzed: 39 clinical parameters, 32 cephalometric parameters and 8 occlusal parameters were examined using the patients’ orthodontic files [clinical examination, casts, cephalometric profile, and facial photography during smile). Results: Six variables were associated with gummy smile: low smile arc, an increased gingival display, an increased Overjet, a high value of ANB, an increased UPDH and LADH. Conclusions: Clinicians should consider these variables during the clinical examination and evaluation of the smile to provide an adequate diagnosis and treatment plan to manage gummy smile.