RESUMO
This study evaluated the clinical validity of the ôWilliamsÆs law of harmonyõ to select artificial teeth in complete dentures, in which there is a similarity between the face and maxillary central incisor (MCIs) shapes. Two photographs were taken (face and MCIs) from 79 students aged 18-25 years, and digitized using a Genius HR-7 scanner. Face and teeth tracings were performed from the photographs using a Easy Digitizer 1.2 software. A non-parametric Chi Square test was applied in the statistical analysis (p<0.05). Results showed a predominance of the square shape (55.70%) in relation to the triangular (27.85%) (p<0.01), and the ovoid (16.45%) (p<0.001) ones. Considering the MCIs shape, the square (67.09%) predominated in relation to the ovoid (18.99%) (p=0), and the triangular (13.92%.) (p=0) ones. The analysis among the shapes showed a lower proportion of identical (10.13%) when compared with no similar (48.10%) (p=0), and similar (41,77%) (p<0.001) ones. Authors concluded that the ôWilliamsÆ law of harmonyõ was not confirmed in the majority of the individuals, and further studies are necessary to actually define which theory satisfies the clinical requirements. The clinical experience and critical sense seem to be more important for a satisfactory esthetic result.