Changes in cell proliferative activity in granulation tissue invading the root canal

Area of Science:

• Endodontics
• Histology
• Cell Biology

Background:

• Root canal preparation aims to clean and shape the canal space.
• Apical preparation extent and presence of irregularities like dead spaces can influence healing.
• Understanding tissue response to canal preparation is crucial for endodontic success.

Purpose of the Study:

• To histologically investigate granulation tissue invasion in simulated apical canals and dead spaces.
• To assess changes in cell proliferative activity using 3H-thymidine incorporation.
• To correlate canal preparation dimensions and dead spaces with tissue response and cell activity.

Main Methods:

• Implantation of custom root canal models with 1, 2, and 3 mm apical canals, with and without dead spaces, in rats.
• Histological examination of granulation tissue invasion after 12 weeks.
• Assessment of cell proliferative activity via 3H-thymidine labeling.

Main Results:

• In models without dead spaces, granulation tissue in 1 mm canals remained viable with high proliferative activity.
• Tissue in 2 and 3 mm canals without dead spaces showed necrosis and decreased proliferative activity.
• In models with dead spaces, tissue invaded 1 and 2 mm canals, maintaining proliferative activity, while 3 mm canals showed no invasion or activity.

Conclusions:

• Apical canal length and the presence of dead spaces significantly influence granulation tissue invasion and cell proliferative activity.
• Shorter preparations (1-2 mm) with dead spaces may support sustained tissue viability and activity.
• Longer preparations (≥3 mm) or those without dead spaces can lead to tissue degeneration and reduced healing potential.