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 butterfly’s wings. All these, as well as the spacing of teeth , follow a mathematical formula called the “Golden Proportion”. 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 “smile line”. 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 patient’s gender and age can influence the degree of roundedness or squaring of the tooth edges. A discussion of the patient’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 “work” in that patient’s mouth.