The face and maxillary arch forms have been suggested as aids that guide the choice of the maxillary central incisor form, in order to achieve an esthetic prosthesis when pre-extractionnal elements or dental reference are missing. The purpose of this study was to determine the validity of William’s geometric theory of tooth selection by studying the correlation between maxillary central incisor form and face form, and to determine whether the maxillary arch can be considered as guide for selection of the maxillary central incisor by studying the relationship between these two factors in a Moroccan population. One hundred and fourteen students comprising 30 males and 84 females whose ages ranged from 21 to 25 years studying in the fifth year at dental faculty of Casablanca were selected as a study subject. Standardized photographs of face, maxillary central incisor and cast of maxillary arches were taken for each subject and then the outlines of these three factors were digitally traced and superimposed by an experienced graphic designer using the "Photoshop C6S” software. The outlines were evaluated by 4 observers and the results were collected. A statistical analysis was subsequently realized using the "SPSS" software. The lowest level of correlation was between the face form and the maxillary central incisor form because it was identical only in 21.9% of subjects, the identical correlation was more pronounced between the maxillary arch form and the maxillary central incisor form (54.4%). The results of the study indicated that there was no highly defined relationship between the maxillary central incisor form and the face form which does not support the “law of harmony”. However, the maxillary arch form and the maxillary central incisor form were correlated, therefore we had concluded that the arch is a more accurate guide for selection of the maxillary central incisor form in complete denture fabrication or in complex anterior restorations.