Designed Versus Achieved 3D Mandibular Teeth Movements and Influencing Factors After First Premolar Extraction With Invisalign: A New Digital Root Model.

Abstract

Objectives: This study aimed to compare the designed and achieved three-dimensional (3D) whole tooth (crown with root) movements and influencing factors of the mandibular teeth in patients who underwent first premolar extractions and were treated with the first series of Invisalign aligners (Align Technology, San Jose, CA, USA).

Materials and methods: Thirty-three consecutively treated adults (Class I with crowding or bimaxillary protrusion) from a single clinical division who completed the first series of aligners after premolar extractions were included in this retrospective study. The pretreatment, designed and post-first series treatment teeth (crowns, roots and bone) models were performed using Clincheck software (Align Technology, San Jose, CA, USA). The superimposition of the models was performed with Geomagic Studio Software 2014 (Raindrop Geomagic Inc., USA) to assess 3D tooth movements. Descriptive and analytical statistics were performed, and a p value < 0.05 was considered statistically significant.

Results: Significant discrepancies between the designed and achieved mandibular tooth movements were observed, particularly in mesiodistal and buccolingual angular movements (p < 0.05). Non-significant discrepancies were found in mesiodistal, buccolingual (except for L1) and vertical (except for L5 and L7) linear movements (p > 0.05). Key influencing factors included aligner generation (G6), attachment design, temporary anchorage devices (TADs) and patient-specific variables (age, gender, overjet/overbite) (p < 0.05).

Conclusions: This study highlights significant deviations between the designed and achieved mandibular tooth (crowns with roots) movements following the first series of Invisalign aligners in patients with first premolar extractions. Key findings demonstrate significant mesiodistal and buccolingual angular tooth movement deviations compared to linear movements (mesiodistal, buccolingual and vertical). Factors such as aligner generation (G6), attachment design, TADs and patient-specific variables (age, gender, overjet/overbite) emerged as pivotal determinants of movement accuracy. These findings may provide further evidence for virtual design during clear aligner treatment.