Ortho Procedures - Interproximal Reduction

Interproximal reduction (IPR) is a practice used to mechanically remove enamel from between the teeth. It is used to help with orthodontic treatments which may include the correction of crowding or reshaping the area between the neighboring teeth. In simple terms, it is the removal of interproximal enamel in order to reduce the overall mesial-distal size of teeth.

Murray L. Ballard was the first to suggest stripping the lower anterior teeth because of crowding. Ballard recorded this in a 1944 paper which was published in The Angle Orthodontist. Other dentists suggested slenderizing the teeth over the next few decades, but it gained mainstream interest in the 1980’s when John J. Sheridan introduced the Air Rotor Stripping technique for Interproximal Reduction. Sheridan published two papers in the Journal of Clinical Orthodontics where he explained his technique. He explained that the IPR procedure can be used as an alternative solution to extracting teeth or expanding teeth during an orthodontic treatment plan. In 2004, Zachrisson explained that IPR can also be used to improve the appearance of the anterior teeth. When an overcrowded arch is properly aligned, "black triangles" can form which can be treated by using IPR on the anterior teeth.

Some evidence has suggested that modern diets which include soft and processed foods have resulted in a decrease in natural interproximal wear. This ultimately makes dental crowding more prevalent.

About half of the proximal enamel can be stripped off without resulting in any dental or Periodontal issues. About 2.5mm of space from IPR of five anterior contacts and 6.4mm of space from IPR from eight posterior contacts can be obtained. It is not recommended for more than 0.5mm - 0.75mm to be removed from each proximal side of the anterior teeth.

Candidates for IPR

Indications for a patient who may be a good candidate for the IPR procedure include mild to moderate crowding and the presence of black triangles in the anterior teeth.

Side-Effects

Excessive heat is known to cause serious damage the pulp of the tooth. To protect the pulp against possible damage from heat, Sheridan and Zachrissan both recommend using water while completing IPR in order to reduce any side-effects from the procedure as it relates to the dental pulp. IPR has also been known to cause dental caries and periodontal disease, however the association has long been debated. An observational study completed by Zachrisson which evaluated 61 patients who went through IPR ten years post-operatively, found no signs of gingival recession or the thinning of the labial gingiva in 93% of the patients included.

In order to limit any side-effect of IPR, it is recommended to apply topical fluoride on the treated teeth or use a part-time wear of a thermoformed fluoride varnish infused retainer. In one study of participants who received fluoride following IPR, the group had lower chances of developing caries on the tooth surfaces which were treated with IPR compared to the group who did not receive any fluoride.

Complications or side effects from interproximal enamel reduction include hypersensitivity, irreversible damage to the dental pulp, increased plaque, higher risk of caries on the stripped enamel location and periodontal diseases.