Root Canal Treatment (RCT): From Traditional Endodontic Therapies to Innovating Pulp Regeneration

Traditional protocols involve the cleaning of the pulp chamber and root canals, the removal of bacteria and of the smear layer, and ultimately to the sealing of endodontic materials filling the pulp, and root lumen. Disinfection combined with mechanical enlargement allows occluding the lumen of the dental pulp with a central master cone, and lateral condensation using a series of small accessory cones. Innovative approaches propose bioengineered scaffolds, growth and transcription factors. Removal of the smear layer reveals different types of globular and non-globular dentins (osteodentin, osteodentin, fibrodentin), cleaning the dentinal walls before chemical or mechanical enlargement of the lumen. Three distinct options open gates for classical endodontic therapies before conventional filling. New pulp therapies derived from apexogenesis and apexification contributes to the formation of a renewed dental pulp, involving totipotent, multipotent and unipotent stem cell. Proliferation of structural cells, signaling factors, transcription factors, metalloproteinases, and cytokines are involved in pulp renewal. Coronal and root microvascularization participate to pulp regeneration and ultimately to pulp mineralization. BMP-2, TGF-β1, MTA and Portland cement may also contribute to the requirements for pulp bioengineering, leading to the future of innovating biological pulp therapies. axial and lateral condensation the root chamber was gradually filled. These steps include the sealing of lateral, secondary and accessory canals [4]. In addition to conventional protocols, more recently attempts were made to regenerate the dental pulp. A few pulp cells proliferate, and renewed the pulp tissue. We envision the formation of a dental pulp and furthermore its mineralization occluding the root lumen. Part of the endodontic cavity was still alive, or proliferation of pulp cells was requested to restore the biology of the dental pulp. Extracellular matrix molecules and/or other growth or transcription factors contributed to regenerate the pulp. In contrast with mechanical methods, biological options were considerate. The innovative approaches proposed were envisaging the implication of structural cells and signaling factors. In this context, we used stem cells, bioengineered scaffolds, growth factors, transcription factors, and cytokines. Altogether, the molecules were implicated in the different procedures that pave the way as biological substitutes for root canal treatments [5]. In the first part of this review, we summarize the basic concepts and related methods devoted to the traditional Root Canal Treatment (RCT). In the second part, we focus on recent concepts aiming to regenerate the dental pulp, leading to pulp renewal that further underwent mineralization. Along these lines of evidences, biological concepts provide the basis of innovating pulp therapies. Why, how and when traditional root canal treatments (RCT) are needed Dental caries are mostly due to bacteria and subsequently to pulp infection [3]. Associated to the dental plaque; microorganisms alter enamel surface, either beneath the proximal contacts areas, or in the face-to-face enamelling occlusal fissures. The initial carious lesions is formed at this precocious stage. The carious lesion crosses the whole enamel thickness and spread laterally along the enlarged dentino-enamel junction. The lesion degrades firstly the mantle dentin. Caries penetrate the subjacent circumpulpal dentin through dentinal tubules Introduction For many years, Root Canal Treatments (RCT) used traditional protocols imposing the careful cleaning of the canals, the removal of the smear layer, and the sealing of the filling materials inside the pulp chamber [1,2]. These procedures were combined with the manual, instrumental or chemical shaping of the root lumen [3]. The preparation of the canal(s) includes chemical mechanical enlargements. We also took into account the coordination of the successive steps, leading ultimately to the preparation of the root canal before filling the empty space. After disinfection, pulp remnants were removed. A clean root canal was obtained after root widening. Endodontic cements filled the pulp chamber, namely when a zinc oxide eugenol mixture was used. Employing a central master cone, and a series of small accessory cones, after