In the absence of teeth that a patient likes in their mouth to duplicate, the dentist follows guides to make the teeth look natural. Like most things in nature, the size distribution of teeth follow a formula which also defines the spacing of petals on a flower, to the proportion of eyes on a face, to the patterns on a butterflyâ€™s wings. All these, as well as the spacing of teeth , follow a mathematical formula called the â€œGolden Proportionâ€. Mathematicians know this as a sequence that common to most living things and artists have used it for centuries.
Once the spacing is set, the tooth lengths are determined by the â€œsmile lineâ€. That is, how the curvature of the upper teeth should follow that of the lower lip in a smile. This curve as well as how much of the teeth will show in a smile can make the patient look younger and more content. A patientâ€™s gender and age can influence the degree of roundedness or squaring of the tooth edges. A discussion of the patientâ€™s desires in these cases steers the dentist in determining their preferences. Using these concepts as a start, elements such as the occlusion, or bite, and clearance from soft tissues, or neutral zone, determine how all these parameters will â€œworkâ€ in that patientâ€™s mouth.