AbstractBackgroundThe visible maxillary arch width (VAW) is an important aesthetic‐determining feature. To date, there is no well‐established methodology to determine the aesthetically optimal VAW in customized treatment planning.MethodsIn this study, the common traits of the dentofacial configuration were investigated in most attractive Asian and Caucasian female smiles. The smiling photo of a subject was digitally modified based on combined variations of VAW, smile width (SW), transverse facial dimensions (TFD), and vertical facial dimensions. These modified photos were assessed for aesthetics. The aesthetically essential parameters were identified, and their mathematic correlations and reference ranges were determined for different vertical facial patterns. Using the obtained results, a mathematic guidance was constructed for customized smile designing. The applicability of this guidance was tested in Asian females.ResultsThe most attractive Asian and Caucasian female smiles have intraracial and interracial commonalities in the VAW‐to‐TFD ratios. The interparopia width (IPD) predominated over facial widths in determining well‐matched VAW and SW. For optimal smile aesthetics, the VAW and SW were correlated as simulated by the formula 1.92 IPD ≤ VAW + 2.3 SW ≤ 2.17 IPD, plus the VAW‐to‐IPD ratio within 0.54 to 0.62 and the SW‐to‐IPD ratio within 0.61 to 0.71, ranges tailored to vertical facial patterns. This constitutes a mathematic guidance for customized planning of the aesthetically optimal VAW. This guidance was preliminarily validated to be applicable to Asian females.ConclusionsThe VAW‐to‐TFD ratios were essential for Caucasian and Asian female smile aesthetics. The mathematic guidance could serve as a reference for customized smile designs for Asian females.