Fluid transport from the dental pulp revisited

Abstract

In the dental pulp surrounded by rigid dentinal walls, an increase in fluid volume will be followed by a rapid increase in interstitial fluid pressure. To maintain pressure homeostasis, a fluid drainage system is required. The dental pulp and apical periodontal ligament lack lymphatic vessels, and the questions are how the transport can take place inside the pulp and where the lymphatic vessels draining fluid from the apical periodontal ligament are located. The drainage of fluid within the pulp must be governed by a tissue pressure gradient (driving pressure) and the fluid is likely transported in loose connective tissue (gaps) surrounding vessels and nerve fibers. We suggest that aging of the pulp tissue characterized by fibrosis will reduce the draining capacity and make it more vulnerable to circulatory failure. When the fluid leaves the pulp, it will follow the nerve bundles and vessels through the periapical ligament into bone channels, where lymphatic vessels are found. In the mandibular canal, lymphatic vessels are localized and the fluid washout rate from the canal is slow, but chewing may speed it up by increasing the fluid pressure. In acute apical periodontitis, inflammatory mediators and bacterial components can be spread to regional lymph nodes via lymphatic vessels inside the jaw bone.

Chitosan–Calcium Aluminate as a Cell-homing Scaffold: Its Bioactivity Testing in a Microphysiological Dental Pulp Platform

“…Thus, the intrapulpal pressure is governed by the interstitial fluid volume within the pulpal tissue. 37 Hydrostatic pressure has been demonstrated to play a role in dental pulp cell regulation and odontoblastic differentiation. 38,39 Thus, the ability to establish controlled simulated pressure is an important feature to incorporate into any model for use in studies investigating the rationale behind direct pulp capping.…”

Pulp biology

“…The existence of lymphatic vessels in the pulp has been debated for many years, and such lymphatic vessels were previously thought to contribute to fluid volume control and drainage in the tissue (6). More recent studies shows that the dental pulp lacks lymphatic vessels (7,8).…”

“…An aged pulp characterized by "restorative scar tissues", fibrosis and mineralization will have a reduced draining capacity, thus making it more vulnerable to circulatory failure (6). To counteract these structural changes, increased dentin thickness may protect the pulp from external stimuli.…”

Insights Into Pulp Biomineralization in Human Teeth

“…This multi-zonal organ from a bioengineering perspective exhibits a relatively higher hydrostatic pressure compared to other organs, contains regenerative cells, and is encapsulated within the harder yet permeable walls of the predominantly inorganic dentin. The natural "control systems" that maintain the interstitial fluid pressure (IFP) of the pulp include lymphatic vessels and capillaries (2)(3)(4). These control systems regulate interstitial fluid flow from the pulp through the dentin tubules to the enamel coronally, and to cementum apically (1).…”