[Orthodontic movement through compact bone and spongious bone. The difference in tissue reaction with 2 different...

Area of Science:

• Orthodontics
• Periodontology
• Bone Biology

Background:

• Orthodontic tooth movement is influenced by bone density.
• Understanding histophysiological responses is crucial for predictable outcomes.

Purpose of the Study:

• To investigate the role of osseous density in orthodontic tooth movement.
• To compare histophysiological responses to root displacement in Wistar rats based on bone density.

Main Methods:

• Histophysiological analysis of mandibular first molar roots in Wistar rats.
• Comparison of responses in compact vs. spongy bone regions.
• Evaluation of cellular and tissue changes under varying forces and displacement directions.

Main Results:

• Compression and hyalinization occur rapidly, peaking around two days, and are more pronounced in spongy bone and with heavy forces.
• Tooth displacement is initially greater in spongy bone, especially with heavy forces.
• Bone resorption patterns differ: slower direct lateral resorption in compact bone versus combined direct and indirect resorption in spongy bone.
• Real tooth displacement is slower in compact bone due to slower resorption and lack of indirect resorption.
• Periodontal space reestablishes during real displacement, and increases in spongy bone.
• Periosteal apposition occurs with light forces; periosteal resorption and intraosseous movement with heavy forces.
• Osteoclast stimulation threshold is lower in compact bone than in spongy bone.

Conclusions:

• Osseous density is a critical factor influencing the rate and pattern of orthodontic tooth movement.
• Spongy bone facilitates faster initial displacement and resorption, while compact bone offers more resistance.
• Force magnitude significantly modulates cellular responses and resorption patterns, impacting treatment outcomes.