Assessment of the accuracy of interproximal tooth reduction using three-dimensional digital models

Blandy, Mark Christopher (2015) Assessment of the accuracy of interproximal tooth reduction using three-dimensional digital models. Professional Doctorate (Research) thesis, James Cook University.

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Abstract

Background: Interproximal reduction (IPR) demonstrates an alternative treatment option for orthodontic space gain in borderline extraction cases. Accurate IPR is essential to achieve proposed treatment objectives and becomes more frequently desired with the increasing popularity of digitally determined treatment plans. However there is currently limited evidence to support that it is an accurate technique to use. Limitations exist in extrapolating in vitro data to a real life clinically setting. For this reason studies are needed to evaluate the accuracy of IPR by means of quantification in an in vivo setting. The use of the Invisalign® system and 3-D digital models may aid the collection of data and the interpretation of the level of accuracy of IPR in a real patient setting.

Aim: To assess the accuracy of IPR as a method of orthodontic space gain using 3-dimensional digital study models. The null hypothesis for this study states that there is no statistically significant difference when comparing proposed and actual amounts of IPR completed (accuracy); the accuracy of IPR within and between upper and lower dental arches; the accuracy of IPR within and between posterior and anterior arch segments.

Materials and Method: Using 3-dimensional models gained via Invisalign's® ClinCheck, pre and post IPR data are available from actual patient cases. Recording of the width of the teeth before and after IPR at case refinement demonstrates how much IPR was actually completed. The proposed total amount of IPR is pre-determined and compared to the actual amount and the difference recorded as a measure of accuracy. A level of clinical significance will also be determined. All measurements are completed using Geomagic Control 2014 (Rock Hill, USA) digital design software.

Results: The results indicate that IPR was not completed with a high degree of accuracy and that the amount of reduction was generally much smaller than what has been determined. Overall IPR was under-achieved by 55.9% per tooth surface in the sample assessed. On average 0.188 mm of IPR was aimed to be completed per tooth surface however only 0.083 mm was actually achieved, showing a significant discrepancy of 0.105 mm per tooth surface. No significant difference was found in IPR accuracy between the upper arch (an average 60.5% under-achievement per tooth surface) and lower arch (an average 49.4% under-achievement per tooth surface) (p=0.062). Also, no significant difference was found in IPR accuracy between the anterior segment (an average 58.6% under-achievement per tooth surface) and posterior segment (an average 42.3% under-achievement per tooth surface) (p=0.352).

Conclusion: IPR might not be completed with a high degree of accuracy and it is generally much smaller than what is trying to be achieved. Clinicians should acknowledge these findings and critique their own technique of IPR accordingly to ensure the highest standard of treatment outcomes.

Item ID: 43725
Item Type: Thesis (Professional Doctorate (Research))
Keywords: 3D models; 3-dimensional models; black triangles; enamel reduction; interdental reduction; Interproximal reduction; IPR; orthodontics; space gain; teeth shaving; tooth striping;
Date Deposited: 19 Apr 2016 07:14
FoR Codes: 11 MEDICAL AND HEALTH SCIENCES > 1105 Dentistry > 110506 Orthodontics and Dentofacial Orthopaedics @ 100%
SEO Codes: 92 HEALTH > 9204 Public Health (excl. Specific Population Health) > 920402 Dental Health @ 100%
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Last 12 Months: 49
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