A smile line parallel to the horizontal is often thought to be most attractive. Even when the eye line does not coincide with this, the illusion of horizontal alignment should be created.

The most attractive smiles all possess one important feature, symmetry. The human eye can easily detect any difference in the size and shape of your front teeth. Making your front teeth the same size and shape, while positioning them around the centre of your face produces the perfect looking smile.

The smile line connects the biting edges of your top teeth. The most attractive smiles possess biting edges which gently follow the curve of the lower lip. A flat smile line suggests aged worn teeth, while a curved smile line makes you and your smile look younger.

The most attractive smiles possess gum lines which follow the upper lip and are symmetrical. The gum line is like a frame to a beautiful painting, it will significantly enhance the appearance of your smile, or significantly detract from your smile if poor in health and shape.

The teeth towards the back of the mouth can always be seen in an attractive smile. In a narrow smile the back teeth are often in shadow (this is called negative space), thus creating the appearance of black triangles at the corners of the mouth and front teeth that stand out.

Embrasures are the natural triangular spaces between the tips of the teeth. For a smile to look attractive embrasures should be smallest between the front teeth and gradually increase in size towards the back.

The golden proportion is a mathematical relationship present through out nature. The ratio 16:1.0:0.6 indicates the amount of tooth surface that should be seen when looking directly at a smile. The closer the teeth are to this ratio the more attractive a smile is.

In reality this golden proportion rule is used as a starting point when designing a new smile.

The most attractive smiles possess teeth of a certain length to width ratio for the two front teeth. This is normally 0.7:1. The length of a tooth should always be greater than its width.

Tooth shade

When designing your new smile it is possible to change the shade (colour), of your teeth. Teeth are not pure white, they possess a range of colours and translucencies. A tooth may be devided into three regions:

1. The cervical third should be more yellow in appearance, even in bright white smiles.
2. The middle third or body of the tooth will be the prominent shade, generally less yellow and brighter in appearance.
3. The incisal third possesses varying degrees of translucency and may appear a little blue or grey.

The most attractive smiles incorporate all these features, without which teeth look artificial.