Related Experiment Video
Updated: Apr 23, 2026
Author Spotlight: Enhancing Dental Pulp Research with Improved Mouse Models
Published on: October 27, 2023
Initial transient accumulation of M2 macrophage-associated molecule-expressing cells after pulpotomy with mineral
Erika Takei1, Yoshimi Shigetani1, Kunihiko Yoshiba1
1Division of Cariology, Operative Dentistry and Endodontics, Department of Oral Health Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Introduction:
M2 (alternatively activated) macrophages are known to participate in wound healing and tissue repair. This study aimed to analyze the temporospatial changes in the distribution and density of M2 macrophage-associated molecule-expressing cells after pulpotomy with mineral trioxide aggregate (MTA) in rat molars to ascertain the role played by M2 macrophages in the healing of MTA-capped pulp tissue.
Methods:
The maxillary first molars of 8-week-old Wistar rats were pulpotomized and capped with MTA. After 1-14 days, the teeth were examined after hematoxylin-eosin staining or immunoperoxidase staining of CD68 (a general macrophage marker) and M2 macrophage markers (CD163 and CD204). The density of positively stained cells was enumerated in the surface and inner regions (0-100 μm and 300-400 μm, respectively, from the wound surface).
Results:
MTA capping initially caused mild inflammatory changes and the formation of a degenerative layer followed by progressive new matrix formation and calcified bridging. At 1-2 days, CD68-, CD163-, and CD204-positive cells started to accumulate beneath the degenerative layer, and the density of these cells was significantly higher in the surface region than in the inner region (P < .05). From 7 days onward, the 3 types of cells displayed an almost normal distribution beneath the newly formed dentinlike matrix.
Conclusions:
After the pulpotomy of rat molars with MTA, M2 macrophage-associated molecule-expressing cells transiently accumulated beneath the degenerative layer under the MTA. This suggests that M2 macrophages participate in the initial phases of the healing of MTA-capped pulp tissue.
Insights
Mineral trioxide aggregate (MTA) pulpotomy in rats shows M2 macrophages accumulate under the MTA initially, aiding pulp healing. These cells help repair MTA-capped pulp tissue during early healing phases.
Area of Science:
- Immunology
- Dental Research
- Tissue Regeneration
Background:
- M2 macrophages are crucial for wound healing and tissue repair.
- Mineral trioxide aggregate (MTA) is used in pulpotomy procedures.
- Understanding M2 macrophage roles in MTA-capped pulp healing is important.
Purpose of the Study:
- To investigate temporospatial changes in M2 macrophage distribution after MTA pulpotomy.
- To determine the role of M2 macrophages in MTA-capped pulp tissue healing in rats.
Main Methods:
- Rat molars underwent pulpotomy and MTA capping.
- Immunohistochemistry for CD68, CD163, and CD204 was performed at 1-14 days.
- Cell density was quantified in surface and inner pulp regions.
Main Results:
- MTA capping induced initial inflammation and a degenerative layer.
- M2 macrophage markers (CD163, CD204) and CD68+ cells accumulated beneath the MTA.
- Higher cell density was observed in the surface region initially, normalizing by day 7.
Conclusions:
- M2 macrophage-associated molecule-expressing cells transiently accumulate post-MTA pulpotomy.
- M2 macrophages appear to play a role in the early stages of MTA-capped pulp healing.
