Stresses and Strains Analysis Using Different Palatal Expander Appliances in Upper Jaw and Midpalatal Suture

Area of Science:

• Orthodontics
• Biomechanical Engineering
• Craniofacial Biology

Background:

• Rapid maxillary expansion (RME) increases the upper jaw's transverse dimension using palatal expanders.
• Traditionally, expanders are anchored to posterior teeth, but bone-borne anchorage is an alternative.
• Understanding stress and strain distribution is crucial for optimizing RME efficacy and safety.

Purpose of the Study:

• To analyze stress and strain in the maxilla, particularly the midpalatal suture (MPS), during RME.
• To compare stress and strain between tooth-borne and bone-borne expanders.
• To investigate the correlation between mechanical strain and Wolff's Law during RME.

Main Methods:

• Finite element models (FEM) were developed using Cone Beam CT data.
• Simulated RME loads were applied via tooth-borne and bone-borne expander models.
• Displacements mimicked single and multiple activations of the expanders.

Main Results:

• Bone-borne expanders required fewer activations than tooth-borne expanders to achieve similar MPS spacing.
• Single activation of bone-borne expanders generated significantly higher strain levels near miniscrews (MSIs).
• Bone-borne anchorage proved more effective, but resulted in increased stress and strain throughout the maxilla.

Conclusions:

• Bone-borne anchorage for RME is biomechanically superior to tooth-borne anchorage.
• Higher strain levels with bone-borne RME may enhance bone remodeling according to Wolff's Law.
• Further research is needed to manage increased stress distribution with bone-borne RME.