Many factors go into creating a beautiful smile. These include color and shade, length and width, relative proportions and individual contours.
When it comes to length and width, it is much easier to change the length than the width. Unless there is natural spacing, changing the width often requires orthodontics which can take many months or even a year or so and usually involves both arches. Moving the gingiva can be accomplished in one visit, and it should be healed adequately to proceed with final restoration in six to eight weeks. No matter how correct the shade selection and color matching is, the tooth or teeth will never look great if they are short and square or, for that matter, too long (which is another discussion).
Aesthetic crown lengthening is different from crown lengthening for retention in that it assumes that there is adequate tooth structure on the facial to retain the restoration, so it is not necessary to involve the palatal or lingual half of the tooth. Ideally one should even try to avoid completely removing the interproximal papilla since recreating the papilla is one of the more challenging and least predictable periodontal surgical procedures.
The first step in any aesthetic restoration is to choose the length of the centrals. Usually, this will be 10.5 to 11 millimeters long. With an average width of 9 to 9.5 millimeters, this will give a proportion of 80%, which is considered ideal. We can change the length by changing the incisal edge or the gingival margin or both. The position of the incisal edge is determined by phonetics and aesthetics. Here, we are concerned about whether we need to remove gingiva and possibly bone to raise the gingival margin. Once the height of the gingival margin of the centrals is determined, based on the chosen length, then it is easy to move in a distal direction and determine the correct gingival height of all other teeth going back to the first molar. The gingival height of the cuspids should be equal to the gingival height of the centrals (a straight line joining them would be parallel to the ground), and the height of the laterals should be 0.5 to 1.0 millimeter below this line. The gingival height of the bicuspids should meet a straight line connecting the gingival height of the cuspid and the first molar at the mesial.
Once the gingival zeniths are determined, then it is simple math to determine how much gingiva and possibly bone must be removed. One needs to provide 3 millimeters of additional space beyond the new planned restoration gingival margins to allow for a shallow sulcus and biologic width. I will talk about the biologic width in the next post.