By Dr. Shaun Weng
Published June 2026
10 min read
Clinical Summary
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Content
IPR accuracy exposed! What this study reveals may surprise you
IPR is used commonly in clear aligners to address lack of space, boltons tooth size discrepancy, tooth proportions, and black triangle closure.
In vivo study, 10 clinicians treated a total of 40 patients with IPR and compared their results to the planned IPR:
• IPR was performed via manual strips + separator rings + measuring gauges
Results:
• The accuracy of IPR in upper arch was 44.95% and lower arch was 37.02%
• Dentists typically underperform the amount of IPR required in both arches (only 5/61 arches there was excessive IPR done)
• The difference between planned IPR and performed IPR was on average −0.49 mm in the upper arch and −0.53 mm in the lower arch
Conclusion (author):
• When considering these results as an actual mm difference, it may not be considered clinically relevant
My Two cents:
• Inadequate IPR = lack of space which may lead to tracking issues
• Ensure gauges when checking are placed perpendicular to contact point and loose
• Worst case scenario you can always do some additional IPR during refinement
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