What are we thankful for this Thanksgiving? Well, would you be surprised if we said a tooth width proportion formula?
Because our blog readers reacted so passionately to Dr. Chris Catalano’s last post on how to create a strong temporary bridge, we knew we needed to bring you another post from him. This time, he’s back with more great advice on bringing CMS skills to everyday dentistry.
(P.S. We’re also thankful for our wonderful 2016 course participants and alumni, all of our brilliant educators, and, most of all, pie.)
Without further ado, here is Dr. Catalano’s not-so-secret formula for smile design success:
Catalano’s Tips and Tricks: An Easy to Use Tooth Width Proportion Formula
To be a great smile designer, one must recognize the many ingredients that make a beautiful smile.
6 Ingredients of a Beautiful Smile
- The beautiful lips that frame the smile.
- The gum tissue that perfectly outlines the smile creating the ideal background for the teeth to stand out.
- The color of the teeth that is uniform, bright, and clean.
- The delicate incisal embrasures that help to give character and form to the teeth.
- The dental arch that is broad and full, allowing for the perfect reflection of light.
- The correct proportion of width and length among each tooth that together look balanced and effortless. Our eyes are not distracted because it is a harmonious blend of nature’s perfection.
Achieving this as a smile designer requires us to be able to address all these pieces to create that “wow” smile.
The “Wow” Smile Formula
I want to share a clinical tip for one of these aspects of smile design. It is a formula used in figuring out the correct tooth width proportion.
As dentists, we are often faced with the problem of trying to figure out tooth width proportions. Whether it is a missing tooth, multiple missing teeth, or an undersized tooth like a peg lateral, determining the correct width can be a challenge.
We are taught that the correct width proportion of teeth should follow the golden proportion. Unfortunately, the golden proportion formula is not that easy to use and it is difficult to translate when you are at the dental chair. Luckily there is a similar formula, created by Stephen Chu DMD MSD CDT, that is practical and easy to use when determining the correct width of a tooth.
Dr. Chu conducted a study where he measured smiles and found correlations with tooth width among the anterior teeth. His study was titled: RANGE AND MEAN DISTRIBUTION FREQUENCY OF INDIVIDUAL TOOTH WIDTH OF THE MAXILLARY ANTERIOR DENTITION. Pract Proced Aesthet Dent 2007;19(4):209-215.
The formula is a simple algebra equation … don’t worry, it’s easy.
Maxillary Central Incisor: Y
Maxillary Lateral Incisor: Y – 2 mm
Maxillary Canine: Y – 1 mm
Mandibular Central Incisor: X
Mandibular Lateral Incisor: X + .5 mm
Mandibular Canine: X + 1 mm
Maxillary Central Incisor to Mandibular Central Incisor Conversion: X + 3 mm = Y
Dr Chu found that Mandibular anterior teeth are a good baseline because they showed less variability. So if you have a case where you think the Maxillary Centrals look too small, check the mandibular teeth, maybe you are right.
Take a look at the two photos of the same smile. I plugged in the formula for two scenarios: One with the Maxillary Central measuring 8 mm and one where it measures 8.5 mm. You can adapt this formula to any central width.
Using the Formula in Everyday Dentistry
An example of how this tooth width proportion formula can help in everyday dentistry involves undersized teeth like peg laterals.
An orthodontist sends a peg lateral case for you to assess and give them feedback about the space you want to bond or veneer. With this formula you can now have a pretty simple quick answer. Remember it is not an absolute rule but it can give you a good start.
This formula is a tremendous help in a case like this. The smile belongs to a 13-year-old patient of mine who has ectodermal dysplasia and has conical shaped teeth. I am working with a local orthodontist to mock up ideal widths so that she can finish his case, creating ideal occlusion and esthetics.
Rather than giving me the case when she thinks it’s finished by holding spaces open, we are going to work together to achieve a more predictable finish. Essentially my plan involves doing composite build ups based on this tooth width proportion formula.
She will send me the case once spaces are created and remove all brackets and wires. He will be in an Essix retainer and I will see him to take my records, upper and lower PVS impressions, CR bite, Facebow, and photos. A wax up will be made at the correct measurements using this formula. I will then create no prep composite veneers and bond to the teeth idealizing the correct tooth widths.
Once I am finished, I will send him back to the orthodontist for her to to put the braces back on. She will now be able to idealize occlusion and esthetics much easier. Once he turns 18 years old we will replace the composite with very conservative pressed ceramic veneers.
Achieving Predictable and Beautiful Results With a Tooth Width Proportion Formula
You don’t need to refer and pray for a good result.
By collaboratively working with your specialist you can get a predictable and beautiful end result. I call it restorative intervention.
I learned this from Vince Kokich DDS, an orthodontist who was instrumental in educating dentists and orthodontists about this process and made groundbreaking insights on how to work together to create an ideal outcome. Our ultimate focus should be on a predictable and successful patient outcome.
This simple tooth width proportion formula can be a big help in smile design, whether you are doing composite bonding on a single tooth or working with an orthodontist to create space for a restoration. It’s one more tool in your smile design belt.