A patient presents to my office with the chief complaint, “I just want my smile to look better.”
I run the usual diagnostics, which include comprehensive examination, full mouth series of radiographs, periodontal evaluation, clinical photographs and study models. Okay, now what?
For the purpose of this post, let’s just focus on the anterior cosmetics.
The patient and I would like to close the diastemas, remove decay, and reshape teeth. But how do we determine what the teeth should look like? Do we need a diagnostic wax up? Do we need crown lengthening? Should we use veneers or full coverage crowns?
First, let’s sit down with the study models. Pour yourself a cup of coffee. Or some wine. I like wine.
I measure the current width and height of each tooth I care about changing. In this case, that’s #5-12. I’m planning on just doing restorations from #6-11, but I want to keep track of # 5 because it’s missing and will get an implant. So I measure using one of my favorite toys, the Dentaguage 3 from Erskine Dental.
One of my mentor’s, Dr. Ed Schlissel, told me this instrument would change my life and, like everything else he’s told me, he was totally right. There are other digital calipers on the market, but this baby also comes with this:
Love, love, love this book. Love it.
It’s full of useful information about tooth proportions. Hooray!
So here are my measurements:
All nice and organized
What next??? Relax. Have a sip of wine. Now we measure the width of the arch from the mesial of # 5 to the mesial of #12. This is a curved line, so you’ll need to curve something around the model and then measure it when it’s straightened. Making pencil marks on a piece of paper will do just fine.
Width of arc from mesial #5 to mesial # 12 = 56.7 mm
Okay, now open that cool book and look at the appropriate chart. It looks something like this:
Memorize these numbers. Just kidding.
From this chart you get the ideal widths of the anterior teeth. If your arc is 56.7, you’ll need a central incisor to be 10.6 mm, a lateral incisor to be 8.4 mm, and the cuspid to be 9.4 mm. Sweet, that will take care of closing the diastemas.
What about the heights??? Relax. Have another sip of wine. The book also give you the ratio to determine the height based upon the width. Some notable dental lecturers will use different proportions, e.g. the RED principle, the golden proportion, etc. The book provides it’s own ratio for you and it’s different for men and women:
Ratios to calculate height and width for central incisor (CI), lateral insicor (LI), and cuspid (C).
Now just multiply the width of the tooth by the appropriate number and you’ll get the height. For those of you keeping track at home, the height of the central will be 12.5 mm, the lateral will be 11 mm, and the cuspid will be 12.1 mm.
You’re almost done. Next you have to determine how you’re going to adjust for the height required. You can lengthen the teeth in a couple of ways:
(1) Bring down the incisal edges. This will increase your vertical overlap, which you may or may not want to do.
(2) Perform crown lengthening by removing soft and/or hard tissues. Make sure you don’t invade the biologic width!
(3) A combination of the two.
Next, write a lab prescription for a diagnostic wax up and give them your specific height and width measurements. Also let them know where you want the incisal edges and gingival margins, as we just discussed.
In this case, the teeth are already very tall. In order to widen them to eliminate the diastemas, we only had to do some minor gingival crown lengthening and contouring. I would have liked to have been able to lengthen the teeth incisally to give more vertical overlap, but that would have made the teeth look way too long. So I asked the lab to keep the incisal edges in the same position and contour the gingival areas as needed.
The diagnositc wax up, all nice and pretty.
Check your wax up to make sure your measurements were correctly incorporated.
Yup, that looks good.
To see how I made the provisional, check out the following post: “Esthetic Zone Execution: How to Get a Great Provisional”