A regression analysis of the overcorrection for the mandibular anterior teeth in trusion with clear aligners

Objective To explore an overcorrection quantization method and related influencing factors through analyzing relationships between the achieved and preset intrusion values of mandibular anterior teeth with clear aligners. Methods Twenty patients receiving Invisalign were recruited. The relative intrusion values in the ClinCheck software were recorded as the preset intrusion. The achieved intrusion values were measured through the digital model superimposition. Statistical analysis was conducted to assess the differences and linear relationships between the preset and achieved intrusion values, and investigate the effect of related factors such as intrusion amounts on the intrusion efficiency. Results For the mandibular anterior teeth, the mean intrusion efficiency was 62.2%, with the highest in the central incisors and the lowest in the canines. The intrusion amounts, incisors labial inclinations, and canine attachment types affected the intrusion efficiency. The differences between the preset and achieved values were significant, and the linear relationship existed. The formula of the intrusion overcorrection for the mandibular anterior teeth is “Z=(W-0.110)/0.533-W”. Z represents the overcorrection and W represents the ideal intrusion. Conclusion The preset intrusion values in the treatment protocol could not be fully achieved. Moreover, correction should be designed in cases of mandibular canine intrusion, large amountsof intrusion, orlingually inclined incisors. Compared to the optimized attachments, the vertical rectangular attachments on the mandibular canines could improve the efficiency.