Stretch force guides finger-like pattern of bone formation in suture

Area of Science:

• Craniofacial biology
• Bone regeneration
• Biomechanical engineering

Background:

• Mechanical tension is used to influence craniofacial bone growth.
• Understanding bone formation in expanding sutures is key for clinical success and avoiding side effects.
• The regular pattern of sutural bone formation under expansion forces remains largely unknown.

Purpose of the Study:

• To investigate the shape, arrangement, and orientation of new bone formation in expanding sutures.
• To explore the clinical implications of these bone formation patterns.
• To elucidate the role of mechanical tension in guiding sutural bone development.

Main Methods:

• Utilized rat premaxillary sutures, histologically similar to human sutures.
• Applied progressive stretch force to widen sutures.
• Employed Micro-CT, Hematoxylin and Eosin (HE) staining, Masson staining, and Alizarin red S/calcein double labeling.

Main Results:

• New bone formation observed within 3 days, exhibiting a finger-like pattern projecting from the maxillae.
• The number and length of finger-like bones increased significantly from day 3 to day 7.
• Bone formation was more pronounced on the nasal side, and the finger-like bones aligned with the direction of the stretch force.
• Inclined forces resulted in inclined bone formation, while excessive compression led to bone fracture.

Conclusions:

• A distinct finger-like pattern of bone formation in sutures is guided by mechanical stretch force.
• This pattern has significant implications for clinical procedures such as maxillary expansion.
• The orientation and morphology of new bone are directly influenced by the direction and nature of applied forces.