Published online Jul 31, 2010.
https://doi.org/10.5395/JKACD.2010.35.4.273
Histology of dental pulp healing after tooth replantation in rats
Abstract
The objective of this study was to observe the histology of dental pulp healing after tooth replantation in rats. The maxillary right first molars of 4-week-old rat were extracted, and then the teeth were repositioned in the original socket. At 3 days after replantation, there was localized inflammatory reaction. But, pulp revasculization and healing had already begun in the root area. At 5 days after replantation, odontoblast-like cells were observed. Tertiary dentin deposition was observed beneath the pulp-dentin border from 1 week after replantation. And tertiary dentin was increased at 2 weeks after replantation. The presence of odontoblast-like cells and the formation of tertiary dentin were continued to 4 weeks after replantation. At 4 weeks after replantation, the deposition of bone-like tissues and cementum-like tissues was observed. This results show that there is a possibility of pulp healing after tooth replantation in rats and the mineralization of tooth can progress. The mineralization of tooth after replantation was initially occurred by the deposition of tertiary dentin, but as time passed, the deposition of bone-like tissues and cementum-like tissues was begun and increased.
Figure 1
Control tooth. A: coronal zone (magnification, ×50). B: Higher magnification of boxed area in A. It presents normal dentinogenesis process. Odontoblasts are arranged along the pulp-dentin border. Beneath the odontoblast layer, regular tubular dentin is observed (magnification, ×400). Abbreviations: D, dentin; DP, dental pulp; OB, odontoblasts.
Figure 2
3 days after replantation. A: There is localizaed inflammation in the coronal pulp (magnification, ×50). B: Higher magnification of upper boxed area in A. Neutrophils and red blood cells are observed in the pulp horn area (magnification, ×100). C: Higher magnification of lower boxed area in A. Blood supply is recovered in the root pulp (magnification, ×200). Abbreviations: D, dentin; DP, dental pulp.
Figure 3
5 days after replantation. A: Coronal zone. Localized inflammation still remains including neutrophils and fibrin networks in the pulp horn area (magnification, ×100). B: Root zone. Formation of odontoblast-like cell layer begins at the pulp-dentin border (magnification, ×100). Abbreviations: D, dentin; DP, dental pulp; OB, odontoblast-like cells.
Figure 4
1 week after replantation. A: Inflammatory lesion disappeared in all of the pulp (magnification, ×400). B: Blood supply is recovered to the coronal pulp. No odontoblast layer formation was formed at the pulp horn area (magnification, ×100). C: At root apex area, there is formation of mineralized region which is similar to the cellular cementum tissues (arrows) (magnification, ×100). D: Higher magnification of boxed area in A. Under the pulp-dentin border, there is a layer of odontoblast-like cells. Some tertiary dentin is deposited beneath the odontoblast-like cells layer (magnification, ×200). Abbreviations: D, dentin; DP, dental pulp; OB, odontoblast-like cells; TD, tertiary dentin.
Figure 5
2 weeks after replantation. A: Tertiary dentin deposition is clear with increased thickness beneath the preexisting dentin (magnification, ×50). B: Coronal zone. Formation of odontoblast-like cells layer is discovered beneath all coronal pulp-dentin border (magnification, ×100). C: Higher magnification of right boxed area in A. At root apex area, there is increased formation of mineralized tissue. It is mixed with tertiary dentins and cementum-like tissues (arrow) (magnification, ×100). D: Higher magnification of left boxed area in A. Beneath the pulp-dentin border, there is a layer of odontoblast-like cells. Increased tertiary dentin deposition is discovered (magnification, ×400). Abbreviations: D, dentin; DP, dental pulp; OB, odontoblast-like cells; TD, tertiary dentin.
Figure 6
4 weeks after replantation. A: Tertiary dentin thickness is increased than that of 2 week after replantation. And pulp space is more narrowed (magnification, ×50). B: Mixed form of tertiary dentin and cellular cementum-like tissues is observed under the external root resorption area (arrow) (magnification, ×50). Abbreviations: D, dentin; DP, dental pulp; OB, odontoblast-like cells; TD, tertiary dentin.
Figure 7
4 weeks after replantation. A, B: Both tertiary dentin and bone-like tissues are formed. A: Bone-like tissues are mixed with tertiary dentin. B: Bone-like tissues occupy the pulp space without tertiary dentin. (magnification, ×50). C: Higher magnification of boxed area in B. In the bone-like tissues matrix, there are Haversian canals and osteoblast-like cells (magnification, ×200). D: As a result of pulp healing, there is formation of bone-like tissue only without tertiary dentin (magnification, ×50). Abbreviations: B, bone-like tissues; C, cementum-like tissues; D, dentin; DP, dental pulp; OB, odontoblast-like cells; TD, tertiary dentin.
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