Evaluation of interproximal reduction in individual teeth, and full arch assessment in clear aligner therapy: digital planning versus 3D model analysis after reduction

Abstract

Aim To evaluate the correspondence between the interproximal reduction (IPR) performed clinically and that programmed in ClinCheck® and further assess which teeth showed an amount of implemented IPR (I-IPR) that corresponds with that programmed in ClinCheck®. Materials and methods Pre- (T0) and post-treatment (T1) ClinCheck® digital models for 75 subjects (30 males and 45 females), mean age (38 ± 15) years, were included. To calculate the amount of I-IPR, Ortho Analyzer software (3Shape, Copenhagen, Denmark) was used to measure the mesiodistal widths for the maxillary and mandibular teeth from second premolar to the contralateral second premolar on the initial (T0) and final (T1) STL models. I- IPR performed by tooth was obtained by comparing the mesiodistal width of each tooth at T0 and T1. The amount of programmed IPR (P-IPR) in ClinCheck® was compared to that implemented clinically using the following formula: IPR difference = (P-IPR) − (I-IPR). Results Statistically significant differences were observed between the average value of digitally programmed and implemented IPR per tooth for both the maxillary (p < .0001) and mandibular (p < .0001) teeth. The mean P-IPR for the maxillary teeth was 0.28 ± 0.16 mm versus the mean I-IPR of 0.15 ± 0.15 mm. In the mandibular arch, the mean P-IPR was 0.31 ± 0.17 mm, while the I-IPR was 0.17 ± 0.16 mm. The mean I-IPR was consistently lower than the mean P-IPR regardless of teeth and sites (p < 0.0001). The difference between the P-IPR compared to the I-IPR was larger for mandibular anterior teeth than for maxillary anterior teeth (p = 0.0302) and larger for maxillary posterior teeth than mandibular posterior teeth (p = 0.0059). Conclusion The amount of implemented-IPR in clear aligner therapy is less than that digitally programmed for most teeth. Regardless of the regions, I-IPR was consistently lower than that programmed. Mandibular anterior teeth and maxillary posterior teeth showed greater discrepancy between P-IPR and I-IPR than the maxillary anterior and mandibular posteriors. Further prospective studies are needed to determine the factors affecting the precision of IPR and the clinical implications of a significantly reduced I-IPR on treatment outcomes.

Comparison of the accuracy of three interproximal reduction methods used in clear aligner treatment

“…Executed IPR was significantly deficient on the mandibular canines with the hand-operated abrasive strip system, which is in line with the findings of Kalemaj and Levrini [ 16 ], because canines are in tight contact with the adjacent teeth and are frequently pushed out of the dental arch in the case of crowding, which makes it challenging to precisely implement the planned IPR [ 30 ]. Furthermore, mandibular teeth are usually in a more crowded state than the maxillary teeth, which is supported by the findings of the present study showing that IPR was dominantly carried out on the mandibular arch (61.6%) when compared to the maxillary arch (38.3%) that was also documented by Hariharan et al [ 31 ].…”

Predictability of Dental Distalization with Clear Aligners: A Systematic Review

“…Through the IPR (interproximal enamel reduction) performed by the orthodontist during treatment with transparent aligners, compensations are obtained to reduce the initial overjet. The results demonstrated a correspondence between the amount of enamel planned and that removed in vivo, confirming the reliability of the ClinCheck software [74,77,102]. This suggests that digital planning can be used with confidence to guide IPR during aligner treatment, providing accurate results [77].…”

The Role of Interproximal Reduction (IPR) in Clear Aligner Therapy: A Critical Analysis of Indications, Techniques, and Outcomes

“…Research shows that in most cases, the executed IPR is lower than what had been initially anticipated [53][54]. Hariharan et al found that the amount of implemented IPR is consistently lower than the digitally programmed values, particularly noted in mandibular anterior teeth and maxillary posterior teeth [55].…”