Principles

The terms ‘aesthetic zone’ and ‘smile zone’ are commonly used to denote the appearance of the teeth and smile. This zone has been shown to influence significantly factors such as social acceptability, self-confidence and professional prospects. It is paramount to undertake a meticulous assessment of the aesthetic zone during patient examination, so that you may best determine which features may require addressing while developing the treatment plan.

It is important in the first instance to gain an insight into the personal perceptions of your patient concerning their dental and facial aesthetics and their expectations; a template questionnaire may prove helpful here.¹

There are certain proportions of both a facial and dento-labial variety that are accepted as being visually pleasing.² These are can be referred to as universal concepts in dental aesthetics. It is important to record the presence of any harmony or disharmony that exists between the varying components of the smile zone in relation to these accepted parameters.

The Golden Proportion is a mathematical concept applied in architectural design and engineering to study design proportionality in the beauty of art and nature. It suggests an ideal mathematical proportion of 1:1.618. In terms of the anterior maxillary dentition, this would imply that the maxillary central incisor should be 1.618 times wider than the maxillary lateral incisor, which in turn would be 1.618 times wider than the maxillary canine when viewed from a frontal direction. Thus, the width of the maxillary canine according to this concept should be 62% of the width of the lateral incisor. However, the Golden Proportion has been described to exist in fewer than 20% of all natural dentitions examined.

A plethora of studies have also investigated the average dimensions of maxillary central incisor teeth, which undoubtedly are the most dominant teeth in the aesthetic zone. The average lengths and widths of the latter have been reported to be 10–11 mm and 8–9 mm, respectively.³ The latter would infer that an average maxillary central incisor would have a length to width ratio of 1.2:1. It is also frequently stated that the central incisor length should be approximately one-sixteenth of the facial height.

Procedures

Clinical evaluation of the aesthetic zone can be subdivided into an assessment of the following:

• Facial features
• Lips and facial skin
• Dento-labial and dento-facial relationships
• Teeth and gingivae.

With your patient comfortably seated upright in the dental chair, adopting a natural head pose, and you seated at the same height, their face when observed from a frontal direction can be apportioned