Shape Shifters

Dr Yasmin Shakarchy and Dr Ahmed Hussain ask, what does the shape of patients’ teeth say about them?

Anterior teeth have a profound effect on the overall smile appearance. Factors that play a role include the position and proportions of teeth, as well their relations with surrounding structures, such as the lips, gums and face.In this article, we consider just the upper incisors and their significant influence on the perception of a smile.

It is important to remember that genetics also play a key role in the shape and size of anterior teeth and therefore overall dental aesthetics.1 Further to this, gender, age and personality must be considered when planning any alterations, making this a holistic and interesting topic to consider.

BASIC TEETH SHAPE

Let us start by considering teeth in their basic form. There are three classifications of maxillary incisors: square, ovoid or triangular.4 Typically, the morphology constitutes a combination of these three basic shapes. The outlines of these features can be found in Figure 1.

The next step is to understand the further classifications of these basic shapes. The modified William’s classification, for example, produced a further six categories. These are based on the facial outline, as well as the gingival-incisal and mesio-distal crown contours.5 The shapes include square-tapering, ovoid-tapering, reverse-tapering, ovoid-square, ovoid-reverse-tapering and squarereverse tapering.

THE “FACE FORM” THEORY

The idea that the shape of the anterior maxillary teeth have a link to facial form has been suggested for over a century. The earliest documented evidence in 1914 discussed that the front teeth are shaped as an inverted front view of the face, meaning a square face merited square teeth, while an ovoid face merited ovoid teeth. Even in the 21st century, this seems to be the most common theory when dental supply companies produce artificial teeth.6

However, we personally believe this not to be necessarily true, and would challenge such ideas. Ibrahiamagic et al in 2001 showed that in a sample of 2000 individuals aged between 17-24, only 30% of subjects showed a correlation between the outline of the face matching the inverted outline of the central incisor. Therefore, the theory that tooth shape is related to the shape of the face is not a steadfast rule.6

GENDER

Does teeth shape have a gender? And if that were the case, defining teeth as feminine or masculine, are we basing this idea on predisposed beliefs of gender? It is widely thought that female teeth are rounder with softer edges, while male teeth tend to be quadrangular with defined angles.7 While this may be a general consensus in aesthetics, scientifically no real correlation exists between tooth form and gender. Therefore, the reliability of tooth shape matching specific genders is questionable or observable in naturally beautiful smiles.

“Gender, age and personality must be considered when planning any alterations, making this a holistic and interesting topic to consider”

AGE

With age, as with all things, the aesthetics of anterior teeth changes significantly. As a result, age is an important factor when designing appropriately beautiful smiles. There are three main age-related changes that are associated with the maxillary anterior teeth. First, the length of teeth. With time, attrition and other forms of tooth wear slowly cause shorter incisors. Secondly, the amount of gum on display, and thirdly, the presence of “black triangles” due to reduced gum volume. All of these age-related factors affect the overall appearance.8

While in our younger years central incisors are more dominant, these same teeth become shorter and smaller with age.

As a caveat, we must understand that patient age does not always correlate with dental age. Aged teeth may have a more rapid onset secondary to dietary intake, internal acids or parafunctional habits.8

PERSONALITY

Basing the shape and design of the upper front teeth, on patients’ personality is one of the oldest theories when designing front teeth. While the science is called morphopsychology, the evaluation of an individual’s personality through their physical appearance is known as the temperamental theory.9

There are many different descriptions for personality types. These can include vigorous, medium or delicate, as well as subdivisions secondary to temperamental types such as sanguine, nervous, bilious and lymphatic. The idea actually dates back to Hippocrates in the 5th century BC. With regards to anterior tooth shape, a “bilious” individual would be expected to have short, broad, tapering incisor teeth, whereas a “sanguineous” individual would possess long, thin, and narrow teeth.9

While such work is anecdotal, there is some truth that the more a dentist knows about their patient, the more successful restorations they produce based on patient desires. If someone is extroverted, typically restorations that are more prominent in shape would fit. While, in those who are more introverted a softer finish would be sought. Constructing a smile that best fits a patient’s personality is always the gold standard.9

Finally, we must endeavour to correlate the design of teeth with cultural norms. As a result, while some conclusions suit certain areas or demographics, they may not convey a different one in the same manner.

CONCLUSION

In conclusion, the use of only one tooth selection theory is likely unacceptable. Instead, we must use a combination of multiple factors and avenues when selecting dental design.

In recent times, there seems to be a preference for ovoid, specifically the tapered-ovoid shape for upper front teeth for females. In contrast men are perceived as angular and square, and should be given tooth shapes that harmonise with their appearance.

While the perception of beauty is subjective, it is nonetheless important to understand fluidly due to its prominent role in patient satisfaction. A successful dentist must factor pre-conceived gender “norms”, age and personality, balancing each uniquely to the patient they treat.