Why the long face? Wavrin Tooth Selection Gauge
This metal "Gauge for selecting artificial teeth" was patented by John A Wavrin in 1921 for the Dentists' Supply Co. of New York.
The Wavrin guide consists of three different measuring arms or bars which were adjusted to the head of the patient. The measurements retrieved from all the three arms collectively mapped the face length and shape. This information served to determine which tooth type was to be selected for constructing the denture, all according to biometric ratios and Dr J Leon Williams’ tapering, square or ovoid shapes classification.
The gauge was made by The Dentists' Supply Co. of New York and distributed by De Trey & Co of London. It measures a total of 32 cm in length. The instructions for use are conveniently etched on the metal guide:
To determine size: Lock bar 3 at right angles to bar 1. Place bars 2 and 3 just outside bony margins of eye sockets and incline lower ends forward past angles of chin. Keep bars 2 and 3 parallel. Rest bar 1 on top of head. Read approximate width upper central at outside of bar 3. Place pencil under chin and read approximate length.
To determine type: Place bar 1 across top of head. Press inner edges of bars 2 and 3 firmly over condyles and prominence of angles of jaw. Equalize facial angle on both sides. The Anatoform Type and Form will be indicated by the pointer.
Tempers, hue and the SPA factor
In 1872, JW White was the first to apply the concept of correspondence and harmony in prosthodontics. Form and colour must be matched to size and complexion respectively, all while considering the wearer’s age and (physical) gender.
However, the patient’s temperament was also included by White as essential characteristic to identify suitable form and colour. Temperamental traits (choleric, phlegmatic, sanguine and melancholic) identified by Western medieval philosophers were, for centuries, a very popular way to classify people and identify their needs for many purposes, including medical diagnosis. In fact, this theory hails all the way back to Hippocrates’ four fluids theory.
More scientific methods based on morphological proportions started to appear around the same time: W R Hall’s Typal form concept (1887), for example, provided some standard measurements based on labial surface curvatures and neck width, and introduced the ovoid, tapering and square form.
In 1906, Berry proposed a biometric ratio that matched the proportions of the upper central incisor to the face proportion. The tooth had to be one sixteenth of the face width at zygoma, and one twentieth the face length.
Wavrin’s Instrumental Guide technique effectively combines the biometric ratio of Berry with Williams’ typical form teeth theory of 1908.
JL Williams (1852-1932) was a renown prosthodontist, histologist and photographer who kept practices in London, as dentist to the Royal Family, and New York. He examined thousands of human skulls from various parts of the world and anthropoid apes to come up with the three types of square, tapering and ovoid upper incisor tooth shapes. His classification is still used in tooth mould charts to this day. His teeth shapes were originally manufactured by the Dental Supply Company of New York. They were sold in Australia as Anatoform, Solarex and New Hue.
As photographic equipment became ubiquitous and easier to use, pre-operative photos helped dentists and technicians immensely in designing and understanding smiles.
The 1950s brought us the incisal line investigations and a reaffirmation of personality characterisation of teeth (masculine vs feminine = square vs ovoid). Sears’ SPA factor remained essential in dental aesthetics for decades (Sex, Personality, Age).
In the last forty years, interalar distance has revealed itself as a much more useful measure to select width of maxillary anterior teeth for dentures.
Modern studies, including analysis of three-dimensional dental and face scans have debunked many long-held beliefs, or at least the need to strictly follow ratios and guidelines.
Aesthetic considerations in tooth and smile design today seem more important than ever. As dental materials and techniques continue to evolve, for prosthetics and restorations alike, the focus has moved from finding that elusive universal and measurable standard of harmony and beauty. It is now more on understanding people’s holistic perceptions of natural beauty and individual aesthetic needs, as it should be.