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IPR: What do I need to know?

IPR (interproximal reduction) is a common procedure used in adjunct with clear aligners. While IPR is a relatively simple and safe procedure; it’s important to understand why IPR is done and how to safely perform it. This will not only assist with patient acceptance and understanding but will also make planned tooth movements more efficient and reliable.

Why IPR?

There are three main ways to create space with orthodontic treatment; 

  • Arch expansion
  • Interproximal reduction
  • Extraction

IPR, which is essentially reducing the enamel on the proximal surfaces of certain teeth in order to gain space, is regularly used in combination with expansion for a vast majority of cases. Given the space gained, IPR can reduce the amount of expansion, proclination and potential need for extraction required for select cases. 

When to Consider

IPR is a good tool to utilise in cases with minimal to moderate crowding and/or cases in which minor discrepancies in OB/OJ need to be addressed.

In the long term, IPR can decrease the likelihood of relapse, allow for more parallel roots / stable contact points and reduce the appearance of black triangles. Barrel shaped or triangular teeth provide more enamel, but the position of the nerve should be considered. 

IPR should be reconsidered in patients with very poor hygiene, very rectangular teeth and teeth with little interproximal enamel.

How much IPR?

It is widely acknowledged that removal of up to 50% of the proximal enamel is possible without dental and periodontal risks. In the anterior and buccal segments this can create between 2.5mm and 6.4mm of space respectively.

How long does IPR take?

It depends on whether you are doing it by hand or using burs or disks, but you’d want to leave a few minutes per tooth. 

Are there risks associated with IPR?

Interproximal reduction of no more than 0.5mm has been shown to have no significant impact on sensitivity or the risk of decay. It is considered a minimally invasive procedure with very little risk to the patient in the short and longer term.

What happens if we don’t use IPR with clear aligners?

Not all cases require significant amounts of space; studies have shown that in cases with minimal crowding one can rely just on arch expansion. However, many adults will experience relapse and crowding (late lower incisor crowding is well-established with advancing age) with more significant space requirements. 

Not to mention, a patient’s occlusion could also impact the need (or lack thereof) for IPR. 

An important differentiating factor in your treatment vs. DIY clear aligners brands is the fact that IPR is used. DIY aligner brands cannot use IPR as a tool given there is no direct dental supervision. 

This can be one tool to educate patients on the need for in-person care. Additionally, over-reliance on arch expansion risks excessive forces being placed on the periodontal tissues and surrounding alveolus, and the development or worsening of recession.

We know IPR can be daunting and it can take time to get comfortable performing it but it should not be disregarded as it can be a helpful tool to obtain a desired outcome!

How can you do IPR?

IPR can be performed in a variety of ways, and it is up to each dentist to choose which technique they use. This may even vary depending on the amount of IPR required. 

  • Air rotor stripping with fine tungsten-carbide or diamond burs
  • Diamond-coated stripping disks
  • Hand-held or motor-driven abrasive strips

It is always advisable to polish the proximal surfaces with hand-held strips as a final step. Watch our video below to learn more!

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