Inflammatory Response Mechanisms of the Dentine–Pulp Complex and the Periapical Tissues

Abstract

The macroscopic and microscopic anatomy of the oral cavity is complex and unique in the human body. Soft-tissue structures are in close interaction with mineralized bone, but also dentine, cementum and enamel of our teeth. These are exposed to intense mechanical and chemical stress as well as to dense microbiologic colonization. Teeth are susceptible to damage, most commonly to caries, where microorganisms from the oral cavity degrade the mineralized tissues of enamel and dentine and invade the soft connective tissue at the core, the dental pulp. However, the pulp is well-equipped to sense and fend off bacteria and their products and mounts various and intricate defense mechanisms. The front rank is formed by a layer of odontoblasts, which line the pulp chamber towards the dentine. These highly specialized cells not only form mineralized tissue but exert important functions as barrier cells. They recognize pathogens early in the process, secrete antibacterial compounds and neutralize bacterial toxins, initiate the immune response and alert other key players of the host defense. As bacteria get closer to the pulp, additional cell types of the pulp, including fibroblasts, stem and immune cells, but also vascular and neuronal networks, contribute with a variety of distinct defense mechanisms, and inflammatory response mechanisms are critical for tissue homeostasis. Still, without therapeutic intervention, a deep carious lesion may lead to tissue necrosis, which allows bacteria to populate the root canal system and invade the periradicular bone via the apical foramen at the root tip. The periodontal tissues and alveolar bone react to the insult with an inflammatory response, most commonly by the formation of an apical granuloma. Healing can occur after pathogen removal, which is achieved by disinfection and obturation of the pulp space by root canal treatment. This review highlights the various mechanisms of pathogen recognition and defense of dental pulp cells and periradicular tissues, explains the different cell types involved in the immune response and discusses the mechanisms of healing and repair, pointing out the close links between inflammation and regeneration as well as between inflammation and potential malignant transformation.

Large three-dimensional cell constructs for tissue engineering

“…Dental pulp assumes a variety of roles including maintenance of tooth homeostasis, pain transmission, and regeneration of dentin [ 84 , 85 ]. Generally, dental pulp is extracted in the case of irreversible pulpitis and pulp necrosis, then the root canal is filled with a rubber-based material [ 86 , 87 ].…”

Association between Cone-Beam Computed Tomography and Histological and Immunohistochemical Features in Periapical Lesions Correlated with Thickened Maxillary Sinus Mucosa

“…Periapical lesions represent an inflammatory process located around the dental apex that is caused by the presence of the bacterial infection inside the dental canals. The bacterial infiltrate spreads to the dental apex and beyond, causing morphological and histological alterations of the root and of the surrounding periapical tissue [ 11 ]. The most common periapical lesions are periapical granulomas and periapical cysts, differentiated by radiological examination, most often supplemented by histopathological examinations [ 12 ].…”

Autophagy in tooth: Physiology, disease and therapeutic implication

“…Throughout lifetime, teeth are continuously exposed to mechanical and chemical stress as well as to microbiologic colonization 20 . Penetration of oral bacteria into enamel and dentin causes dental caries, without therapeutic interventions, caries will advance through dentine, triggering pulpitis and eventually pulp necrosis and periapical infection 21 …”

“…Tooth mounts intricate defence mechanisms 21 . A layer of odontoblasts, which line the pulp chamber towards the dentine, contributes to reparative dentin formation and protects pulp tissue 22‐24 .…”