One of the most common chief complaints of new orthodontic patients is that they don’t like the gaps between their teeth. Spaces bother patients more than crowding, overbites, underbites, or other dental problems because they are more visible at a conversational distance. While most spaces are caused by too much distance between adjacent teeth, a “triangular space” exists between teeth that are touching. What is a triangular space, what causes it, and what can be done about it?

What causes triangular spaces?
The sides of natural teeth are not flat. They are either tapered or curved. Because they are not flat, there is always space between the contact (the location where the teeth touch) and the crest of the underlying bone. The interdental papilla, the gum tissue between the teeth, usually fills this space. When the interdental papilla is missing or too small to fill the space, a triangle is created by the sides of the teeth above and the gum tissue below.

How does the shape of the teeth affect triangular spaces?
The size of the interdental papilla is affected by the shape of the teeth, the overlap of the teeth before orthodontic treatment, the periodontal health, and the height of the gum tissues around the teeth. Teeth that are very flat on the sides, and therefore lay close together to begin with, don’t have much room for tissue between them. Luckily, this lack of tissue between flat-sided teeth is not very noticeable. Tapered teeth, however, require a lot of tissue to fill the space between them. Even small changes to the size of the interdental papilla between these teeth are conspicuous.

What causes the loss of interdental papillae?
Three things usually cause changes to the size of the interdental papillae. First, if teeth overlap before orthodontic treatment, there may not have been room for the gum tissue to exist in the first place. Aligning the teeth doesn’t alter the size of the papilla; it merely reveals that it was never there. Second, the health of the gingiva affects its height between the teeth. Periodontal conditions cause the gums to recede, creating visible spaces between the teeth. And third, the overall height of the gingiva decreases with time, even in the absence of disease. This happens following decades of brushing, flossing, and natural changes that accompany aging. As the interdental papillae change shape and size, triangular spaces between the teeth begin to appear.

What can be done to treat triangular spaces?
There are three ways to reduce the size of triangular spaces between the teeth. First, increasing the amount of tissue between the teeth reduces the amount of unfilled space. Unfortunately, gingival grafting or papilla “plumping” procedures have not been very effective for this purpose. Second, restorative dentists can bond or veneer tapered teeth to reduce or eliminate triangular spaces. Such restorations are pricey and may be destructive to the teeth being restored. The third and only procedure that your orthodontist can perform is changing the shape of the tapered teeth so they can be pushed more tightly together. This is accomplished using a technique called “interproximal reduction” or IPR using very smooth diamond instruments. IPR effectively reduces most triangular spaces, but the shape and size of the teeth involved may limit the amount of reduction. Additionally, IPR changes the bite as closing the spaces reduces the size of the arch.

NOTE: The author, Dr. Greg Jorgensen, is a board-certified orthodontist in the private practice of orthodontics in Rio Rancho and Albuquerque, New Mexico. He was trained at BYU, Washington University in St. Louis, and the University of Iowa. Dr. Jorgensen's 30+ years of specialty practice and 10,000+ finished cases qualify him as an expert in two-phase treatment, extraction and non-extraction therapy, functional orthodontics, clear aligners (Invisalign), and multiple bracket systems (including conventional braces, Damon and other self-ligating brackets, Suresmile, and lingual braces). This blog is for informational purposes only and is designed to help consumers understand currently accepted orthodontic concepts. It is not a venue for debating alternative treatment theories. Dr. Jorgensen is licensed to diagnose and treat patients only in New Mexico. He cannot diagnose cases described in comments nor select treatment plans for readers. Copyright laws protect the opinions expressed here and can only be used with the author's permission.