Anterior aesthetics part 3: Tooth position and design

Designing the shape of anterior teeth is more difficult than it sounds at first but does become easier after a study of dental anatomy and a systematic process that is followed. There are certain rules that must be followed to create anterior tooth shapes that are aesthetic and also mimic nature. Between these rules there is room for creativity in terms of tooth colour, textures and variations that can allow the operator to add a personal touch to the case.

When designing anterior aesthetics, start with the central incisors. The position of the central incisors is paramount to the position of the entire dentition as they are the most aesthetically important teeth and all teeth posterior to them are designed based on the central incisor position. This is analogous to full denture design: The incisal length, midline and incisal angle is one of the first things we design into the wax rims and the occlusal plane is designed from this point backwards.

When designing the position of the central incisor, pay attention to the principles explored in the first two parts of this post. The dental midline can be placed perpendicular to the midpoint of the interpupillary line, in line with the midline of the nose or in line with the mid philtrum and chin. Some patients have quite asymmetric faces and so deciding on the midline can require some creativity on the dentist's part. The incisal edge should be placed in relation to the upper lip in the context of the patient's age and gender. It should be placed within the boundaries of phonetics in a labiolingual dimension and incisogingival dimension. From the midline and incisal edges, average widths and lengths of teeth (Table 1) can be used to approximate the extensions of the distal wall and gingival margin respectively. However the final placement of the gingival margin should be decided when seeing how mobile the lip is on full smile.

		Central incisor	Lateral incisor	Canine
Length (mm)	Male	10.2	8.7	10.1
		9.4	7.8	8.9
Width (mm)	Female	8.6	6.6	7.6
		8.1	6.1	7.1

 Table 1: Average anterior tooth widths and lengths for males and females

When designing any anterior tooth (covered in the next few parts) start with a rectangle with its borders at the incisal edge, mesial and distal wall and gingival margin. Then it is a matter of determining the highest incisal contour, gingival zenith, mesial and distal contact point and joining the dots (Figure 1).

Figure 1: Start with a rectangle, find the boundaries and connect the dots

In part 4 I will summarise the finer aspects of the tooth outline of anterior teeth.