Interproximal Reduction, When, Why, and How | 9 MINUTE SUMMARY
Interproximal Reduction, When, Why, and How | 9 MINUTE SUMMARY In this episode, I dive into the fundamentals of interproximal reduction(IPR) when to use it, why it matters, and how to do it effectively.We’ll cover how much IPR can safely be carried out, compare differentclinical protocols and their pros and cons, and take a critical look at howaligner software plans IPR (and where it may fall short).This summary is based on Dr. Flavia Artese’s insightful lecture at therecent American Association of Orthodontists Annual Session in Philadelphia,along with insights from my own clinical research and experience. How much IPR is possible? Recommended amount ½ to 1/3 of outer enamel Estimate with periapical radiographs are inaccurate, under-estimateas well as over estimate Meredith 2017 Brine 2001 Quantity of the enamel each interproximal surface Kailasam2021 systematic review, with an excellent table created by Bosio in 2022 highlightingthe enamel present and hypothetical safe reduction, ranging from 0.3-0.7mm,with 5-10% greater enamel on the distal surfaces Can all teeth have IPR?· Triangular teeth are idealo Large interradicular distance, roots canapproximate with no issue· Square shaped teeth not idealo Reduced interradicular distance, rootapproximation of 0.8mm = loss of crestal bone Taera 2008 Are we accurate with IPR? Johner 2013 AJODO· Manual strips Vs rotary disc Vs oscillatingstrips = all underperformed IPR by up to 0.1mm Protocols: Small Vs Large · 0.1-0.2mm manual strips· 0.3mm+ larger reduction · Polishing required – If not = 25 um furrows retainplaque Jack Sheridan1989 Separation posterior region· Separator – Requires measuring of premolarbefore and after· Bur – needle buro Parallel occlusal planeo Recontour tooth surface to create contact point· No separator - requires contact point to be broken, advantageis the measurement of the IPR site is accurate Bolton’s analysis· Based on excess, rather than tooth removal Proportionality· Width o Canine 90% of central incisoro Lateral 70% of central incisor IPR planningBolton’s discrepancy + Tooth proportionality= whento add or remove tooth structure However· “Don't do pre-emptive stripping for balancingtooth mass ratios between arches. Chances are it will work out just fine” Jack Sheradin 2007 JCO Method of use for 4 mm of IPR:· Posterior to anterior – Jack Sheridano Posterior IPR first, followed by distalisation,e.g. 4-5 first, distalise 4o Maintain arch length with stops etc, maintainanchorage· Anterior to posterior – Farooq o Anchorage preserving o Tony Weir 2021 the most common site in clinicalpractice was the lower anterior segment IPR on overlapping teeth· Not possible to achieve ideal anatomy withmotorised IPR instruments · Posterior IPR first, distalise, followed byanterior alignment and IPR – Flavia· Use of handstrips is possible on overlappingteeth - Farooq Limits of IPR· 4-5mm, although Sheridan described possible 8.9mm,technically challenging· IPR is not a possibility for sagittaldiscrepancy: Greater Bolton’s discrepancies in class 3 and class 2malocclusions, SR 53 studies Machado 2020, greater in class 2 and 3 casesalbeit a small difference of 0.3-0.8% Retained primary 2nd molars· Idealise occlusion· Consider root morphology divergence, as post IPRspace may not closeo If divergence greater than crown, reconsider asspace closure unlikely Why do we need to use IPR with aligners? Dahhas 2024· Alogrythm reduces the number of aligners· More IPR rather than saggital correction· IPR staged inappropriately with large IPR whilstcontact point overlap, which is difficult to perform adequate anatomicalreduction
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