Interproximal Reduction (IPR) is a common orthodontic procedure involving the precise removal of a small amount of enamel from between the teeth. This technique is also referred to as slenderizing, stripping, or enamel reproximation. Orthodontists perform IPR to create micro-spaces that allow for better tooth movement and alignment during treatment. The procedure is routine and has been utilized in orthodontics for decades, becoming particularly prevalent with the rise of clear aligner therapy.
Why Orthodontists Recommend IPR
Orthodontists use IPR to manage specific clinical situations where there is a minor mismatch between the size of the teeth and the size of the jaw arch. The most frequent reason for recommending IPR is to resolve mild to moderate dental crowding without requiring the extraction of permanent teeth. By reducing the width of several teeth by tiny amounts, enough total space can be generated to straighten the alignment.
The technique is also employed to correct tooth size discrepancies, often quantified using a calculation known as the Bolton analysis. If the upper and lower teeth do not align perfectly for a proper bite, IPR can subtly reshape the teeth to achieve ideal interdigitation and improve the overall occlusion.
Furthermore, IPR is used to improve aesthetics by reshaping the contact points between teeth. This reshaping helps to eliminate or minimize the appearance of “black triangles”—the small, dark triangular gaps that can appear near the gum line after teeth are straightened. By changing the shape of the tooth’s side from a point to a broader contact area, the gum tissue can be encouraged to fill the space more effectively.
How the Procedure is Performed
IPR is a controlled procedure where the orthodontist first determines the exact amount of space needed using digital scans and treatment planning software. The amount of enamel removed from a single tooth surface is minimal, typically ranging from 0.2 mm to 0.5 mm, which is only a fraction of the total enamel thickness. This reduction is often spread across multiple teeth to distribute the change and maximize the space gained.
The procedure can be performed using one of several tools, depending on the required reduction and the tooth’s location. Manual abrasive strips, similar to very fine sandpaper, are used for the smallest adjustments, offering exceptional tactile control. For larger reductions, the orthodontist may use a mechanical reciprocating handpiece or a fine diamond rotary disc. These powered tools are often color-coded to indicate the grit and thickness, allowing for incremental and predictable material removal.
The patient experience during IPR is straightforward, and it is usually performed without local anesthetic. Since enamel is the outermost layer of the tooth and contains no nerves, patients typically feel no pain. The sensation is most often described as a vibration, pressure, or a scraping feeling as the abrasive tool runs along the tooth surface. To ensure accuracy, the orthodontist uses specialized metal gauges to precisely measure the space created, confirming that the required reduction has been achieved.
Protecting the Treated Teeth Afterward
After the reduction is completed, the orthodontist thoroughly polishes the reduced surfaces to smooth away any microscopic roughness created by the abrasive tools. This step is important because a rough surface can easily trap plaque, which could increase the risk of decay.
Following the polishing, a topical fluoride varnish or a remineralizing agent is applied to the treated areas. This application helps to seal the enamel and enhance the remineralization process of the remaining tooth structure. While the removed enamel does not grow back, the amount taken is well within the safety limits of the tooth’s natural structure, leaving sufficient enamel for a healthy tooth.
Studies have shown that the procedure does not increase the risk of dental decay or periodontal disease when performed correctly. Any temporary sensitivity to hot or cold that a patient might experience resolves quickly. Maintaining a rigorous oral hygiene routine remains the most important factor for ensuring the continued health and strength of teeth that have undergone IPR.