Interproximal reduction (IPR) is the removal of a small amount of enamel from the contact areas between teeth to create space for orthodontic tooth movement. It is used widely with clear aligners and is also part of contemporary fixed appliance treatment. Used well, it is a precise and safe way to gain space; used carelessly, it can leave problems that cannot be undone.
When to Use IPR?
Determining the appropriate time to perform IPR is not straightforward. It requires careful planning and staging, similar to preparing for a full-mouth rehabilitation. Often, the planning aspect of IPR is overlooked in orthodontics, both for aligners and fixed appliances. Establishing a protocol is crucial, as it guides clinicians on the appropriate amount of IPR needed and helps them utilise the tools available in their clinical practice to deliver reliable and safe IPR.
Many practitioners tend to treat IPR as an afterthought, focusing primarily on moving the teeth. However, the two processes are interconnected. This is why education on IPR is vital to ensure it is integrated effectively into treatment plans.
Case Selection
Not all patients are suitable candidates for IPR. Suitability depends on factors such as the anatomy of the patient’s teeth and the required amount of movement. One of the most regrettable outcomes is when IPR leaves spaces that cannot be corrected, as enamel removal is irreversible. Following a protocol is essential to avoid such scenarios and ensure that IPR is carried out with due consideration.
Who Requests IPR?
Aligner companies typically request IPR. They use AI-driven or algorithm-driven plans to determine how much the teeth overlap and the amount of IPR needed. However, these plans can have errors, such as inaccuracies in scans or digital manipulations that systematically undersize the teeth. Understanding the limitations of these plans is crucial to avoid over-delivering on what is clinically necessary. Check the planned amounts against the patient’s tooth anatomy and contact points before you start.
Timing of IPR
Delivering IPR in one stage or visit may not be ideal. Instead, it can be spread out by planning it at the beginning, reassessing in the middle, and delivering any residual IPR needed at the end. This approach maximises the effectiveness of IPR in a safe, reliable, and anatomical manner.
IPR is not a one-size-fits-all procedure. Different tools may be needed depending on the specific requirements, and the process should be fluid, with reassessments throughout the treatment. Similar to monitoring a patient’s periodontal health, IPR requires ongoing assessment and treatment as needed.
Long-term Risks of IPR
Concerns about IPR often focus on the potential risks of enamel reduction, such as increased sensitivity and caries. However, mechanically removing enamel is different from demineralisation due to caries. Research indicates that mechanically removed enamel can remineralise and become resistant to caries. Long-term studies over ten years have shown no increase in caries or compromised periodontal health, nor increased sensitivity.
It is important to note that these positive outcomes are based on patients with a low caries risk and IPR performed according to a strict protocol. Without proper planning, anatomical IPR, and polishing, the benefits shown in research may not apply. Adhering to a protocol is essential to prevent potential problems associated with IPR.
Good IPR planning also helps at the retention stage: accurate scans or impressions of the final tooth positions mean retainers that fit well. Wimbledon Orthodontic Laboratory makes Essix retainers, the TransRetainer™, bonded retainers and orthodontic appliances for orthodontists across the UK, for NHS and private patients. Send us iTero, 3Shape, Medit, Dexis or Owandy scans, or impressions by post; we deliver nationwide and run our own driver in London. Contact Wimbledon Orthodontic Laboratory to send your next case.