Quantitative evaluation of implemented interproximal enamel reduction during aligner therapy.
Level 3 - non-randomized controlled study
Prospective observational cohort study evaluating clinical measurements across multiple operators
PubMed 33339043 · doi:10.2319/040920-272.1
What was done
Fifty patients treated with aligner therapy by six orthodontists were prospectively evaluated. Impressions were taken at treatment start and after the first set of aligners. Programmed interproximal reduction (p-IPR) was compared with implemented interproximal reduction (i-IPR) across 464 teeth using Wilcoxon signed-rank test, Kruskal-Wallis, and multilevel mixed regression to identify technical factors influencing accuracy.
What was found
Implemented IPR was significantly less than programmed IPR, with a mean difference of 0.15 mm (SD: 0.14 mm; P = .0001). Lower canines showed the largest discrepancy, and mesial surfaces were reduced more accurately than distal surfaces. Discrepancies were smaller when using burs (coeff.: 0.09, P = .029) and measuring gauges (coeff.: -0.06, P = .013). Performing round tripping prior to IPR slightly improved precision compared to previous alignment (coeff.: -0.021, P = .041).
Why it matters
Orthodontists systematically under-perform planned enamel reduction during aligner therapy, which can compromise planned tooth movement. Using burs, thickness gauges, and pre-reduction alignment significantly improves reduction precision.
Limits
The study is observational without randomized comparison of stripping methods or tools. Details regarding patient age, malocclusion severity, and the specific aligner system used are not reported in the abstract.
Cited by
- context Invisalign treatment shaves off 0.2 to 0.4 millimeters of interproximal enamel to retract teeth inward.