Labiolingual Loading Biomechanics on Central Incisor Under Different Periodontal Conditions: A Finite Element Study

Area of Science:

• Orthodontics
• Biomechanics
• Dental Implantology

Background:

• Alveolar bone loss and tooth proclination complicate orthodontic treatment.
• Understanding biomechanical responses to force application is crucial for predictable tooth movement.

Purpose of the Study:

• To compare the biomechanical effects of forces applied at different lingual and labial sites on a maxillary central incisor with simulated alveolar bone loss and proclination.
• To evaluate the influence of varying degrees of alveolar bone loss on tooth displacement and periodontal ligament stress.

Main Methods:

• Finite element models simulating 4 levels of alveolar bone loss (0 to 2/3 root length) and varying labiolingual inclination (U1-SN angle 97°-115°).
• Application of combined retraction (1.5 N) and intrusion (0.5 N) forces at specific labial and lingual crown sites.
• Analysis of tooth displacement, crown inclination changes, and periodontal ligament (PDL) stress distribution.

Main Results:

• Labial forces improved sagittal control with increasing proclination, while lingual forces reduced distal displacement.
• Increased bone loss led to complex horizontal movements, vertical extrusion, and reduced 3D control.
• Periodontal ligament stress patterns shifted and intensified with greater bone loss; PDL modulus variations significantly affected displacement.

Conclusions:

• Alveolar bone loss is the primary determinant of tooth displacement patterns in orthodontics.
• Increased bone loss exacerbates lingual tipping and extrusion; labial force offers superior control over lingual tipping.
• Force application at the cingulum area minimizes adverse movements, and PDL elastic modulus variations influence initial displacement but not movement rate.