Introduction
Sir, I should be grateful to the editor if he would kindly consider printing my response to Messrs Bukhary, Gill, Tredwin and Moles' article about The influence of varying maxillary lateral incisor dimensions on perceived smile aesthetics (BDJ2007; 203: 687–693).
As the original innovator of the application of the golden proportion to dental aesthetics, as described in my article, Dental aesthetics and the golden proportion (J Prosthet Dent1978; 40: 3), it always gives me great pleasure to assess the numerous studies which evolve as a result of my work. Regrettably, the studies are often negative and usually due to simple misunderstandings of the practical application. Despite this, there are thousands of dentists worldwide who are happily using these principles successfully. I should appreciate the opportunity to respond to this article, as it gives me the chance to set the record straight while there is still time.
Messrs Bukhary, Gill, Tredwin and Moles' interesting study included six identical photographs in which each picture shows a different width of the lateral incisor.
The first part of their study was to find which width looks the best to most people, including dentists.
The second part was to see whether the preferred width was in the golden proportion.
The study suggested that in their Figure 1b, the width of the lateral was 62% of the width of the central (62% is the golden proportion). A digital dental grid, designed precisely in the golden proportion, superimposed on this photograph, shows that the width of the lateral, rated at 62%, is in fact much narrower. It would seem that there was an error in their measurements.
The study then showed that Figure 1d was the preferred width and this is precisely in the golden proportion as shown by the following three methods:
Figure A shows digital golden proportion software (The PHI grid) superimposed on the three photographs of the original article Figures 1b-d.
Figure B shows the golden mean gauge superimposed on an enlargement of the same photograph as above.
Figure C shows a transparent overlay superimposed on the same picture as above.
The above clearly show, and confirm the observation that, when the lateral is in the golden proportion to the central, most people say it is the most attractive relationship.
Figure D shows that the easiest way of assessing the golden proportion is simply with a hygienic, disposable card grid, straight onto the upper incisors. More information on the golden proportion in dental aesthetics can be found on http://www.goldenmeangauge.co.uk.
In summary, this interesting study actually confirms that the preferred measurement is the golden proportion.
This study also suggests that the aesthetic relationship of lateral to canine could be as important as central to lateral because in Figure D the dominant line of the canine including the canine tip falls exactly on the golden proportion grid line for the canine.
The authors respond: We would like to thank Dr Levin for his interest in the article but would like to address several of the points that he has made:
(1) Careful inspection of the paper shows that Figure 1 photograph c and not photograph b as proposed by Dr Levin is actually the golden proportion. Unfortunately despite much work done by Dr Levin he has incorrectly misread the paper and used the wrong photograph. However, he is indeed correct in his conclusion that the photograph he has used is much narrower than 62%, with the lateral being 57% of the width of the central incisor.
(2) Figure 1d represents the lateral incisor being 67% of the width of the central incisor and is not the golden proportion as suggested. Assuming that there is a measurement error of up to 1 mm and the width of a central is 10 mm, it is reasonable to expect a measurement error of up to 10%. With such a measurement error it is quite conceivable that Mr Levin's measurements are at variance from ours. However, we took the precaution of conducting our measurements under magnification using high resolution images. These measurements were verified by three of the authors. The publication process inevitably means that the images reproduced in the BDJ are of lower resolution and magnification than those used in our research.
Mr Levin should not be too upset that most people preferred the 67% lateral as this is only 0.05 mm wider than suggested by the golden proportion.
(3) While the golden proportion makes a useful starting point what the results of our study have shown is that it is possible that patients may actually prefer a proportion that is close to but not exactly the golden proportion.
(4) It was not the intention of this study to be negative about the golden proportion, which has served as a useful and pragmatic guide for many years. However, our results have shown that rigid application of principles by dentists/technicians to a set formula are not always what the patient prefers. Concepts such as 'beauty' or 'aesthetics' are social constructs and cannot be standardised according to a system of universal norms. They have been shown to vary both between cultures and over time. Contemporary clinical practice places an increasing focus on patient-centred outcomes and accordingly we recognise that successful treatment will heed and incorporate our patients' views and preferences.
