Cellular origins and differentiation control mechanisms during periodontal development and wound healing

Abstract

In the context of cellular origins, odontogenic epithelium and oral epithelium are the sources for junctional epithelium during development and during wound healing respectively. In contrast, both odontogenic and non-odontogenic mesenchyme contain the progenitors for gingival fibroblasts in developing tissues while in wounded tissues, gingival fibroblasts are derived from gingival connective tissues and comprise a heterogeneous population of cells with diverse properties and functions. Periodontal ligament, bone and cementum cell populations apparently originate from dental follicle progenitor cells during development, but during wound healing derive from ancestral cells in periodontal ligament and bone. Cellular differentiation in developing periodontium is governed in part by epithelial-mesenchymal interactions that generate specific signals which regulate selective cell populations in time and space. On the other hand, differentiation during wound healing and regeneration is regulated by a vast array of extracellular matrix informational molecules and by cytokines that induce both selective and non-selective responses in the different cell lineages and their precursors. Further, several important signalling systems are irretrievably lost after development is complete. Thus, in the context of cellular origins and differentiation, developing and wounded periodontal tissues exhibit fundamental differences. Future prospects for improved healing and regeneration of periodontal tissues may derive from identification and isolation of informational molecules that are stored in connective tissue matrices. These molecules and elucidation of their functions may open new perspectives in our understanding of the biology of periodontal wound healing and may provide novel approaches to periodontal regeneration.

Root and Bone Response to the Proximity of a Mini-Implant under Orthodontic Loading

“…This means that the root contact group was nearer the PDL so might be more affected by differentiated cells such as cementoclasts or cementoblasts from the PDL than the root perforation group. 21,23 Root resorption almost occurred within 0.6 mm from the mini-implant (Figure 1), which means that a miniimplant closer than 0.6 mm from the root can stimulate root resorption. Therefore, the implant should be placed more than 0.6 mm from the root.…”

“…The latter may be mildly stimulated to grow by a signal from the PDL. 21 There may be precursor cells in the PDL 21,22 that differentiate into cementoclasts or cementoblasts from a signal. The root contact group showed greater root resorption and cementum repair than the root perforation group, which had close contact with the root and the microcrack or fracture (Figure 3).…”

Emdogain® in carcinogenesis: a systematic review of in vitro studies

“…However, periodontal regeneration is a complex, multifactorial process involving molecular interactions in and between mesenchymal and epithelial cell lines, which include periodontal ligament cells, bone cells, gingival fibroblasts, and epithelial cells (1)(2). The essential features of successful regeneration are de novo cementogenesis, osteogenesis, and assembly of periodontal ligaments onto the acellular cementum.…”

Periodontal Stem Cells: a Historical Background and Current Perspectives

“…The concept of "stem cells" in adult oral tissues can be traced back to the identification of a subset of cycling populations that possessed self-renewal characteristics with extensive proliferative capacity in epithelial tissues: oral epithelium, junctional epithelium, salivary glands, ectomesenchymally derived tissue lamina propria of the oral mucosa, pulp, and the attachment apparatus of the oral cavity [6,[16][17][18][19]. In the late 1970s and early 1980s, Melcher's group at the University of Toronto focused on the biology of the periodontium with specific emphasis on the periodontal ligament.…”