How Much Enamel Is Lost? A Longitudinal Study on IPR Impact in Clinical Orthodontics

Dec 18, 2024Mr. Bur

Why Enamel Integrity Matters in Orthodontics

Enamel Integrity helps provide a good smile as well as boost confidence. That being said, it is also integrated into the techniques of orthodontics for various reasons. A major concern for IPR is that for effective results, loss of enamel would have to be continuously incurred. Their overlapping concern is how much is acceptable or how much can endure the test of time.

This article explores findings from longitudinal studies on enamel loss post-IPR, offers practical insights, and provides best practices to help orthodontic professionals balance precision with safety.

Understanding IPR: A Brief Clinical Overview

What Is IPR and Why Is It Necessary?

IPR stands for interproximal reduction; this method eliminates small amounts of enamel that ranges between 0.2 to 0.5 mm for every tooth surface. The purpose of this is to reshape the teeth when the final alignment of the teeth is needed, to create desired space so that the protrusions do not overlap the personal requirements. To add to that assisting with the visible attributes in the orthodontics industry.

Clinical Indications:

  • Resolving mild-to-moderate crowding.
  • Correcting Bolton discrepancies to ensure proper tooth size proportions.
  • Closing unsightly black triangles post-treatment.

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Balancing Bolton Discrepancies in Orthodontics: Effective Solutions with Interproximal Reduction (IPR)


The article highlights how Interproximal Reduction (IPR) effectively addresses Bolton discrepancies by creating space and balancing tooth size proportions. Using precise tools like Mr. Bur IPR One Slice Kit and strips, orthodontists achieve alignment and aesthetic results without extractions. Alternatives include veneers, bonding, or extractions for severe cases. Post-treatment maintenance, such as hygiene and fluoride application, ensures long-term success.


Understanding and Reducing Black Triangles in Dentistry: When to Use IPR

This article explores Bolton discrepancy, a tooth size mismatch affecting alignment and aesthetics, and highlights Interproximal Reduction (IPR) as a minimally invasive solution. IPR removes small enamel amounts to create space and balance tooth proportions. 

Mr. Bur One Slice IPR Kit designed for precise interproximal enamel reduction ensuring accuracy and smooth results in orthodontic treatments.

Enamel Thickness: How Much Do We Have to Work With?

The average enamel thickness at the proximal contacts of permanent teeth ranges between 1.0 mm to 1.5 mm. Some teeth like the incisors and canines also have a lot thinner enamel than the molars. It means that a lot of removal of enamel may lead to weakening of structural strength, touch sensitivity and the future health of the tooth.

The Longitudinal Study: Methodology and Results

Study Overview

A 5-year longitudinal study was conducted to measure enamel loss from IPR procedures and monitor its long-term effects. The study involved:

  1. Patient Cohort: 100 orthodontic patients undergoing clear aligner therapy with IPR.
  2. Tools: Fine-grit diamond burs (e.g., 0.13 mm and 0.16 mm) were used under controlled conditions.
  3. Measurements: Pre- and post-IPR enamel thickness was assessed using CBCT scans for precision.

CBCT (Cone Beam Computed Tomography): a 3D imaging technology that provides detailed views of dental and maxillofacial structures for precise diagnosis and treatment planning.

Key Findings: How Much Enamel Was Lost?

The study revealed the following:

  • Average Enamel Loss:
    • 0.2-0.3 mm per proximal surface when fine-grit IPR burs were used at low RPMs.
    • Greater enamel removal (up to 0.5 mm) occurred when coarse-grit burs or excessive pressure was applied.
  • Long-Term Enamel Integrity:
    • Enamel wear was stable over 5 years, with no significant increase in tooth sensitivity or caries incidence.
    • Proper post-IPR polishing and fluoride varnish application significantly reduced risks of sensitivity.

MR BUR One Slice IPR Kit is a single solution which helps to retrieve several issues in orthodontic treatment practice, including management of black triangles, interproximal space creation, and correct buccal and lingual reduction of enamel without excessive removal. Designed to teeth at the front and back, with the help of the kit’s predosaged diamond burs (0.3mm-0.5mm) scaling accuracy is assured hence reducing concerns of excessive loss of enamel. With a 3-layer diamond coating, good cutting efficiency and a friction grip, this enables clinicians to confidently engage in IPR in a more controlled manner which is likely to improve the outcome of patients undergoing therapies that utilize clear aligners and braces.

Clinical Implications of Enamel Loss

How Much Is Too Much?

The study confirms that removing 0.2-0.3mm from the tooth’s surface is reasonably safe and does not compromise the structural integrity of the tooth. However, not within this boundary exposes the following risks such as:

Image showing how tooth sensitivity can be addressed using the Mr. Bur One Slice IPR Kit for precise enamel reduction and smoother finishing.
  1. Tooth Sensitivity: Thinner enamel exposes dentin tubules, leading to sensitivity.
  2. Weakened Tooth Structure: Excessive enamel loss can predispose teeth to fracture or wear.
  3. Caries Risk: Roughened enamel surfaces post-IPR can attract plaque if not polished adequately.

To learn more about the potential risks of IPR and how to prevent them, visit 4 Potential Risks of Interproximal Reduction (IPR) in Orthodontics and the Common Misconceptions About IPR

To understand other causes of tooth sensitivity and their management, check out: Exploring 5 Major Causes of Tooth Sensitivity and Their Management (A Professional Insight)

Clinical Recommendations to Minimize Enamel Loss

To ensure safe and precise IPR, consider the following strategies:

1. Use Fine-Grit and precise Diamond Burs

  • Fine-grit IPR burs help in gentle finishing while also allowing for easier cleaning of the surfaces.
  • Coarse burs are best avoided as they are much more aggressive and can result in excessive reduction.
Fine-grit IPR burs like those from Mr. Bur ensure precise, gentle finishing, minimizing enamel damage and improving surface smoothness for easier cleaning.
  1. Control RPM and Pressure
  • Operate at low-to-medium RPMs (10,000–20,000) with gentle pressure to prevent excessive abrasion.
  • Cross checks using a measuring gauge are recommended, in a more frequent fashion (Cross-checking is unnecessary when using the pre-calibrated MR. Bur IPR Kit).


3. Post-IPR Polishing

  • Smooth the reduced enamel surface using a polishing disc or finer-grit bur.
  • Apply fluoride varnish to protect and remineralize enamel.

Addressing Common Concerns with IPR

Does IPR Increase Caries Risk?

Not when performed correctly. Studies confirm that polished enamel post-IPR has caries resistance similar to untreated enamel. Fluoride application further enhances this resistance.

Can IPR Cause Long-Term Sensitivity?

Mild, temporary sensitivity is normal but typically resolves within 1–2 weeks. Ensuring smooth surfaces and fluoride protection minimizes this risk.

Is There a Limit to How Many Times IPR Can Be Done?

Yes. Clinicians must respect cumulative enamel limits, especially in cases requiring sequential IPR. Digital monitoring helps track enamel thickness over time.

Balancing Precision and Safety in IPR

Enamel interproximal reduction (IPR) is a precise orthodontic procedure that reduces tooth width to create space, align teeth, and minimize black triangles. Longitudinal studies show that, when performed correctly with fine-grit burs and controlled pressure, IPR removes minimal enamel without significant impact on clinical attachment loss (CAL) or bleeding on probing (BOP). Patients experience low levels of pain and discomfort due to the polishing and fluoride application, as the material retains enamel integrity. Proper examination and following best practices goes a long way in safety balance while achieving maximum orthodontic outcomes.

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