Effects of different patterns of movement for correcting a deep curve of Spee with clear aligners on the anterior teeth: a finite element analysis

Introduction: Social media enhanced access to information, making it easier to share dental treatments. Objective: This study aimed to conduct a descriptive analysis of the clinical cases published on the Align® Global Gallery platform. Material and Methods: A retrospective cross-sectional study of 1,582 cases was conducted, data extracted referred to the following basic information: case number; patient’s age; reported gender; Invisalign® package modality; treatment time; aligner exchange protocol; total number of aligners per arch; type of retainers, and inclusion of initial and final panoramic and cephalometric radiographs. Results: The majority were young (mean age 24.6 years, SD = 11.6), female patients (69.1%) with Class I malocclusion (39.4%) and crowding (77.9%). Comprehensive treatment was common (66.5%), with an average treatment time of 18 months (SD = 8.56; 95% CI = 17.6-18.5), with the most frequently reported aligner exchange protocol being 7 days (49.5%), with an average of 50.6 aligners in the upper arch (SD = 26.9; 95% CI = 49.2-51.9), and 48.7 in the lower arch (SD = 26.1; 95% CI = 47.4-50.0). Arch expansion (66.9%) and interproximal reduction (59.7%) were common approaches, while extractions were rare (4.3%). In most cases, initial lateral cephalometric (80.4%) and panoramic (93.3%) radiographs were presented. However, the final radiograph count dropped, with lateral cephalometric at 69.2%, and panoramic at 82.2% of cases. Conclusion: Cases in the Align®Global Gallery mostly feature Class I patients with crowded teeth, treated with expansion and interproximal reduction. The absence of standardized information and post-treatment data restricts the applicability of these findings to broader Invisalign® treatment trends.

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Biomechanical analysis of clear aligners for mandibular anterior teeth intrusion and its application in the design of new aligner attachment

Xiao,

Cheng,

et al. 2024

Preprint

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Background: During the process of intruding the mandibular anterior teeth with clear aligners, the teeth are susceptible to unintended displacement, leading to complications such as excessive alveolar bone resorption and root exposure, which can significantly compromise the treatment outcome. Therefore, it is imperative to investigate the underlying causes and develop effective coping strategies. Methods: CBCT data from 30 patients were collected before and after the intrusion treatment of mandibular anterior teeth. Changes in the labial-lingual inclination of the mandibular anterior teeth and the distance between the root apex and alveolar bone wall were statistically analyzed. Finite element models of mandibular anterior teeth undergoing vertical intrusion with standard clear aligners were created with eight incisor mandibular plane angles (IMPA) to assess displacement trends, labial and lingual moments, and crown contact forces. Additionally, six aligner attachments were designed to simulate and analyze their biomechanical mechanisms. Results:Significant differences were observed in changes before and after treatment. When the IMPA was 90°, the crown experienced a labial moment. The labial root control ridge increased the labial moment of the crown, while the lingual root control ridge and labial attachments increased the lingual moment. The lingual fossa excavation group also increased the labial moment. The lingual root control attachment enhanced the lingual movement of the crown, whereas the lingual excavated attachment promoted labial movement. During the intrusion of mandibular anterior teeth, a comprehensive design incorporating labial intrusive attachments, labial root control ridges, lingual root control ridges, and lingual fossa excavation can be employed to ensure true vertical intrusion of the lower anterior teeth. Conclusion: This study performed finite element analysis under different inclination angles and various working conditions of the mandibular anterior teeth to reveal their biomechanical changes during intrusion, and innovatively designed the lingual fossa excavation, contributes to the development of novel orthodontic techniques and improves clinical treatment outcomes.

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Effects of different patterns of movement for correcting a deep curve of Spee with clear aligners on the anterior teeth: a finite element analysis

Cited by 4 publications

References 34 publications

What is the role of second molars in leveling the curve of Spee? A finite element analysis study

What is the role of second molars in leveling the curve of Spee? A finite element analysis study

Descriptive analysis of the cases published in the Align® Global Gallery

Biomechanical analysis of clear aligners for mandibular anterior teeth intrusion and its application in the design of new aligner attachment

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