Sir, in the article on perceived aesthetics of maxillary incisors1 no mention was made of the Golden Ratio. This is a ratio 1.61:1 and is also referred to as the Divine Number. It has been known for over 2,500 years. It occurs in nature and science and has been used in architecture; reputedly the Parthenon was built to these proportions. There are claims of its use by artists such as Dali. Many psychologists have carried out tests presenting a range of rectangular shapes to subjects. There is a consistent finding that the most pleasing shape conforms to the Golden Ratio.

G. E. Cooper, C. J. Tredwin, N. T. Cooper, A. Petrie and D. S. Gill respond: We would like to thank P. Erridge for his interest in our article. We tested the aesthetic impact of a number of width-height alterations of the maxillary central incisor. During the design stage of the research we reviewed past published findings to help decide which ratios should be included in our study. The research of Wolfart et al.2 clearly demonstrated that the 62% width-length ratio (the Golden Proportion) of the maxillary central incisors was judged as one of the least aesthetically pleasing ratios for both laypeople and dentists. In fact this study found that the 80% ratio was one of the most pleasing ratios for both assessor groups. Bearing this in mind we selected the 80% ratio as our midpoint and produced our photo range spanning approximately 15% either way of this ratio which did not include the Golden Proportion. The results of our study also clearly demonstrated that the assessors did not like the photos where the width-length ratio approached the Golden Proportion as shown by the ranking of the 69% and 66% ratios. Therefore, the assumption that the Golden Proportion need not be included was reinforced.