Interproximal Reduction (IPR) is a precise and established procedure in modern orthodontics, frequently used to facilitate tooth movement, especially in conjunction with clear aligner therapy. This technique involves the controlled and selective removal of a small amount of outer tooth material to create necessary space within the dental arch. By modifying the contact surfaces between adjacent teeth, IPR helps orthodontists achieve a more stable, functional, and aesthetically pleasing final alignment. The procedure is an alternative to tooth extraction in cases of mild to moderate crowding, offering a conservative approach to space management.
Defining Interproximal Reduction
Interproximal Reduction involves carefully reducing the width of specific teeth by shaving a minimal amount of enamel from the sides where they touch their neighbors. This process is also known as enamel stripping, slenderizing, or reproximation. The amount of material removed is typically very small, generally ranging between 0.2 millimeters and 0.5 millimeters from a single contact point between two teeth.
IPR is necessary to resolve minor to moderate dental crowding. The space created allows overlapped teeth to straighten and move into their correct positions. It is also used to correct a Bolton discrepancy, which is a mismatch in the overall size ratio between the upper and lower teeth.
Adjusting tooth size through IPR helps to ensure that the upper and lower teeth fit together correctly, improving the long-term stability and function of the bite, or occlusion. IPR is also employed to reshape teeth with triangular forms, which helps eliminate small spaces near the gum line, commonly referred to as “black triangles.”
Methods Used During the Procedure
IPR relies on specialized abrasive tools for precise material removal. One common method uses manual abrasive strips, which are thin, flexible metal strips coated with diamond particles. These strips are carefully drawn back and forth through the contact point, providing tactile control for very small reductions.
For reductions requiring slightly more material removal, mechanized options are often utilized, such as rotary discs or oscillating handpieces equipped with abrasive tips. Rotary discs are thin, circular instruments coated with fine diamond grit that spin at a controlled speed to quickly and efficiently shape the tooth surface. Oscillating strips move side-to-side in a controlled manner, offering a balance between the speed of a rotary tool and the precision of a manual strip.
The orthodontist uses specialized measuring gauges, which are calibrated metal strips of known thickness, to confirm the exact amount of space created between the teeth. This measurement step is performed both before and during the reduction. This ensures the target dimension is reached and prevents over-stripping.
Once the desired space is created, the final step involves polishing the reduced enamel surfaces to a smooth finish. This smoothing process uses ultra-fine polishing strips or burs to remove any remaining microscopic roughness. Polishing helps restore the natural contour of the tooth and reduces the potential for plaque accumulation.
Addressing Tooth Health Concerns
The most frequent concern regarding Interproximal Reduction is the safety of permanently removing a portion of the tooth’s surface. The enamel layer on permanent teeth is relatively thick, measuring approximately 1.0 to 1.5 millimeters at the proximal contacts. Since IPR typically removes a maximum of 0.5 millimeters per contact point, the procedure only affects a fraction of the total enamel thickness.
Some patients may experience a temporary increase in tooth sensitivity immediately following the procedure due to the slight exposure of underlying dentin tubules. This sensitivity is usually mild and resolves quickly, often within a few days, as the tooth naturally adjusts to the minor surface change. The discomfort is rarely severe enough to require local anesthetic, with the procedure itself often described as a feeling of pressure or light vibration.
Studies have shown that when IPR is performed correctly and followed by appropriate polishing, there is no increased long-term risk of dental decay or cavities. The polished surface is resistant to plaque adhesion, similar to untouched enamel. To further support the structural integrity of the teeth post-procedure, orthodontists often apply topical fluoride treatments or varnishes.
The application of fluoride aids in the remineralization process of the reduced surface, strengthening the enamel and protecting it against acid erosion. The long-term success and safety of IPR depend on the skill of the practitioner and the patient maintaining good oral hygiene, including diligent brushing and flossing of the newly contoured areas.