It is very common for me as an orthodontist to see teeth that are disproportionately small or large compared to the other teeth in the mouth. I see teeth that are too small much more often, and this is especially common with the upper lateral incisors (the second teeth back in your mouth starting from the front). Several times a week, I see new patients with laterals that are anywhere from a millimeter or two too narrow (which patents often never realized they were small), to ones that are very noticeably narrow, which we call “peg laterals”. When these patients are starting orthodontic treatment with braces or invisalign, it is important to recognize this size discrepancy so that their bite can be planned accordingly to fit ideally when we are finished.
The goal of this article is to explain what is involved with getting the bite to fit properly when there is a tooth size discrepancy, as this concept often can cause some confusion with parents. An analogy that I often use is that your bite is like a shoe box fitting together. The upper teeth are like the lid of the shoe box: they are broader than the lowers, and they should make a framework around the lower teeth. The lower teeth are like the box itself, which should all fit securely inside the framework of the uppers. Picture what would happen if you took the snuggly fitting cap to a shoe box, and replaced it with a smaller lid (like having several upper teeth that are too small) and tried to place this on the box. If you forced it to fit, the lid would likely tear, and there would be extra space left at these tears when the lid was pushed down. This is what happens in the mouth when there are upper laterals that are too small, and the remainder of the teeth are positioned in a correct bite: there are spaces that are left over where the teeth are narrow, and we are often physically unable to close these spaces anymore (the upper “lid” would become too small and will not fit to the lower anymore).
So what options do we have when this occurs? Here are the three most common:
- Leave spaces adjacent to the small teeth at the end of orthodontic treatment, and after the braces are removed your general dentist will restore them to their proper width. I usually recommend this option when the laterals are noticeably small, and the “widening” of these teeth by your dentist results in a much nicer appearance. Your dentist will help you choose the best materials to use, whether it be bonded composite, or ceramic veneers or crowns. There is an extra charge outside of orthodontics for your general dentists to perform this procedure.
- Reduce the size of the lower teeth to match the missing width of the upper teeth. I usually recommend this option when the missing upper lateral width is relatively small and the upper laterals appear very nice even though they are a bit smaller. With this option, the front 6-8 teeth are made slightly narrower by sanding between where these teeth meet one another. It basically creates a number of small spaces, after which I close the lower spaces (which creates a smaller “lower box”), which then allows for full closure of the upper spaces (using the existing smaller “upper lid”). The advantage of this option is that no further dental procedures will be needed after orthodontic treatment. The downside is that there will be some removal of enamel- they key is to keep it conservative, and for me to go no where near the point that it causes increased risk of future decay, increased long term sensitivity, or an appreciable loss of tooth structure. If too much tooth reduction or slenderizing would be needed, I always recommend option 1 above.
- Leave the lower teeth “back” from an ideal bite. A skilled orthodontist will always try to get your bite as aligned and as healthy as possible, but sometimes this is an option if the size discrepancy of the laterals is small enough, and the bite can be left purposefully off a bit in order to close all the upper spaces. I don’t do this as commonly, but it is another option if patients don’t like the thought of the the other two options above.
Which option is best for you? If you know you have abnormally narrow teeth, I will be happy to help you decide which option is best. Every bite is unique, and we will decide on a custom treatment plan to finish your teeth as healthy and as attractive as possible!
Dr. Dan Rejman is board certified by the American Board of Orthodontics, and is the councilor for the College of Diplomates of the ABO for the Southwest and Rocky Mountain regions.