Smile Principles

These are 10 of the most important principles of smile design we use in helping to design your smile.

Horizontal Alignment

Ideally the smile line should be aligned parallel to the horizontal. This would be preferable even when the eye line or ear line does not coincide with this level.


Symmetry around the centreline is of great importance for an aesthetically pleasing smile. Where this is not possible, the illusion of symmetry should be created. This illusion is enhanced by ensuring symmetry of the two upper front teeth and other teeth close to the midline. Microsurface tooth anatomy and shape detail can also influence light reflections to create this illusion of symmetry. Further away from the midline, asymmetry is not so noticeable.


Phonetic tests (asking the patient to make the sounds F, S, M and E) determine the most desirable position for the biting edge of upper front teeth and can be critical in revealing which way worn teeth can be lengthened.



Smile Line


Correct Smile Line

The smile line connects the biting edges of top teeth and ideally should follow the curvature of the lower lip. A flat smile line conveys an aged and worn look. A curved smile line looks more youthful. Women tend to have more curved smile lines than men.


Gum Line

Gum Line

Many individuals do not display gumlines in smiling, but where gumlines are displayed the gumline connects the highest points of the gum levels of the upper teeth. Ideally this line should follow the line of the upper lip, to ensure a reasonable and co-ordinated gum exposure and an optimal display of teeth. A gum display of up to 2 to 3mm height can be acceptable.


Smile Width

Correct Smile Width

A smile of normal width allows us to see the ideal progression from front to back teeth. In a narrow smile the side teeth are often in a shadow, so front teeth appear to stand alone. In a wide smile the contour shape of the back teeth needs to follow the contour shape of the front teeth and previous dark restorations in back teeth can become a distraction in a smile.



Smile Embrasures

Embrasures are the little triangular spaces or "cutouts" between the tips of teeth. They are necessary to prevent teeth looking like piano keys. Embrasure spaces should be smallest between the two front teeth and become gradually larger further back in the mouth. Young people generally display larger embrasure spaces.


Golden Proportion

Smile Golden Proportion

The golden rules of proportion can be broken but they can provide an excellent starting point. These rules describe an ideal ratio of the visible widths of the upper front six teeth (ie :1.6:1.0:0.6)


Tooth Proportion

Guidelines for Tooth Proportion

There are also guidelines for the ideal proportions of each individual tooth. The recommended ideal width to height ratio for the two front teeth is: 0.7:1. Tooth proportions and Golden Proportions can have visually acceptable presentations by expert shaping and surface detail features that create illusions with light reflection.

Canine Bite Guide

A Protective Canine Bite Guidance needs to be created to prevent the nashing of both back and front incisor teeth in left and right grinding movements. A functional aesthetic canine bite guidance will protect your new Smile Masterpiece®.