Ultrastructural relation between nerve terminals and dentine bridge formation after pulpotomy in human teeth

Inoue, Hiroshi; Taniguchi, Koki; Okamura, Kazuhiko; Izumi, Toshio; Tamura, Naoharu; Kajiwara, Shinichi; Yamada, Kazuhiko; Kuroda, Etsuko; Watanabe, Keiji; Kitamura, Katsuya

doi:10.1016/0003-9969(95)00018-k

Cited by 10 publications

(6 citation statements)

References 18 publications

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“…They found a large number of adrenergic nerve endings in odontogenic areas near the basal ends of odontoblasts, and speculated that they may somehow modify dentinogenesis. Similar observations have recently been made by Inoue et al (1995) in human teeth. The authors speculated that the close association of these nerves must have some effect on odontoblast cell function.…”

Section: (B) Innervation Of Dentin (1) Developmentalsupporting

confidence: 73%

Dynamics of the Pulpo-Dentin Complex

Pashley

1996

Critical Reviews in Oral Biology & Medicine

368

246

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Dentin has a relatively high water content due to its tubular structure. Once dentin is exposed, this intratubular water is free to move in response to thermal, osmotic, evaporative, or tactile stimuli. Fluid shifts across dentin are thought to cause sufficient shear forces on odontoblasts, nerve endings, nearby fibroblasts, and blood vessels to cause significant mechanical irritation, disruption, or damage, depending on the magnitude of the fluid shift. Even in the absence of fluid shifts, the water-filled tubules provide diffusion channels for noxious (i.e., bacterial products) substances which diffuse inward toward the pulp, where they can activate the immune system, provide chemotactic stimuli, cytokine production, and produce pain and pulpal inflammation. Viewed from this perspective, dentin is a poor barrier to external irritants. However, pulpal tissues react to these challenges by increasing the activity of nerves, blood vessels, the immune system, and interstitial fluid turnover, to make the exposed dentin less permeable either physiologically, via increased outward fluid flow, or microscopically, by lining tubules with proteins, mineral deposits, or tertiary dentin, thereby enhancing the barrier properties of dentin, and providing additional protection to pulpal tissues. These reactions involve dentin and pulp, both in the initiation of the processes and in their resolution. These responses of the dental pulp to irritation of dentin demonstrate the dynamic nature of the pulpo-dentin complex.

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Section: (B) Innervation Of Dentin (1) Developmentalsupporting

confidence: 73%

Dynamics of the Pulpo-Dentin Complex

Pashley

1996

Critical Reviews in Oral Biology & Medicine

368

246

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“…In previous studies, it has been suggested that varicosities had an effect on the differentiation and/or function of pre-odontoblasts/odontoblasts during healing after pulpal damage (Sato, 1989;Byers et al, 1990;Inotue et al, 1995). Inoue et al (1995) reported that vesicle-rich varicosities tended to be distributed in the odontoblastic layer in reparative dentinogenesis. Vesicle-rich varicosities may induce a trophic effect to either odontoblasts or the environment around varicosities in dentin/pulp by releasing the contents of the vesicles.…”

Section: Discussionmentioning

confidence: 98%

“…Besides sensory transmission, sensory nerves have also been suggested to play a role in the vasodilation or plasma extravasation in dental pulp by releasing their neuropeptides (Gazelius et al, 1987;Olgart et al, 1991;Heyeraas et al, 1994;Kerezoudis et al, 1994a,b). The nerve terminal in the predentin or odontoblastic layer has also been suggested to influence the function of odontoblasts during wound healing (Sato, 1989;Byers et al, 1990;Inoue et al, 1995). However, the ultrastructural interaction between the sensory nerves and odontoblasts still remains to be clarified.…”

Section: Introductionmentioning

confidence: 96%

An Ultrastructural Study of the Relationship between Sensory Trigeminal Nerves and Odontoblasts in Rat Dentin/Pulp as Demonstrated by the Anterograde Transport of Wheat Germ Agglutinin-Horseradish Peroxidase (WGA-HRP)

et al. 1996

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Because the ultrastructure of the trigeminal sensory nerves in dentin, especially in relation to odontoblasts, remains to be clarified, we investigated the relationship between the trigeminal sensory nerves and the odontoblast processes using the anterograde axonal transport technique by injecting wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into the rat trigeminal ganglion. Light microscopically, the nerves labeled with WGA-HRP were mainly concentrated at the pulpal horn, forming a nerve plexus at the subodontoblastic region and penetrating the predentin/dentin about 50 to 70 microns. Ultrastructurally, HRP reaction products were observed intra-axonally in the myelinated (A delta) and unmyelinated (C) axons in the subodontoblastic region. Most nerves lost the Schwann sheath and were naked in the predentin/dentin. The labeled varicosities were close to the odontoblast processes in the dentinal tubules. No synaptic structures could be detected between the varicosities and the odontoblasts, but a gap about 20 nm wide was found between them. One type of varicosity was a rich mitochondria-containing varicosity, while the other was a rich vesicle-containing (large dense core vesicles and small clear vesicles) one. The reaction products were also found in the extracellular spaces surrounding the axons. Sometimes the reaction products were seen in the coated pits or the endocytotic vesicles of the odontoblast processes. The present study demonstrated that nerve endings (varicosities) derived from the trigeminal ganglion were present in the dentinal tubules, and that WGA-HRP extracellularly extruded from the sensory nerves in the odontoblastic layer or predentin/dentin. These findings thus suggest that sensory nerves may have some (e.g., trophic) effect on either odontoblasts or the environment around the sensory nerves in the dentin/pulp.

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“…However, it is still unclear if this influence is a direct physiological effect between the cell–cell interaction of the odontoblast and nociceptive neuron, a neurotoxic effect of capsaicin directly on odontoblasts, or if these effects are due to an indirect physiological effect such as neuropeptide influences on pulpal microcirculation. In the literature, it has been questioned if a synaptic relationship exists between the odontoblast and its pulpal fibres (Inoue et al. 1995).…”

Section: Discussionmentioning

confidence: 99%