Bruxism Simulation in Aligner Therapy: Effects on Restored Posterior Teeth

Area of Science:

• Dental Materials Science
• Orthodontics
• Biomaterials Engineering

Background:

• Parafunctional habits, such as bruxism, generate substantial occlusal forces.
• These forces can negatively impact the longevity of dental restorations.
• Orthodontic treatment with clear aligners (CAs) may be further challenged by these habits.

Purpose of the Study:

• To evaluate the surface wear of Class II composite restorations under simulated parafunctional loading.
• To assess the integrity and wear of clear aligners (CAs) during simulated bruxism.
• To compare the effects of normal masticatory forces versus bruxism-mimicking forces on restorations and aligners.

Main Methods:

• An ex vivo study involving 34 posterior teeth with Class II composite restorations.
• Teeth were subjected to either normal masticatory forces or high-intensity cyclic forces simulating bruxism.
• Restorations and fitted clear aligners were analyzed for surface wear and integrity changes.

Main Results:

• Parafunctional loading significantly increased surface degradation of composite restorations.
• Clear aligner (CA) wear and thickness reduction were significantly higher under parafunctional forces compared to normal forces (0.0304 mm vs. 0.0122 mm).
• Reduced positional accuracy was observed under parafunctional forces, indicated by higher RMS errors (33.5 vs. 21.5 units).

Conclusions:

• Parafunctional forces significantly exacerbate surface wear in Class II composite restorations during clear aligner therapy.
• Simulated bruxism compromises the structural integrity of clear aligners, affecting treatment accuracy.
• Durable restorative and aligner materials are crucial for successful orthodontic treatment in patients with bruxing habits.