The Junctional Epithelium: from Health to Disease

Abstract

The junctional epithelium is located at a strategically important interface between the gingival sulcus, populated with bacteria, and the periodontal soft and mineralized connective tissues that need protection from becoming exposed to bacteria and their products. Its unique structural and functional adaptation enables the junctional epithelium to control the constant microbiological challenge. The antimicrobial defense mechanisms of the junctional epithelium, however, do not preclude the development of gingival and periodontal lesions. The conversion of the junctional to pocket epithelium, which is regarded as a hallmark in disease initiation, has been the focus of intense research in recent years. Research has shown that the junctional epithelial cells may play a much more active role in the innate defense mechanisms than previously assumed. They synthesize a variety of molecules directly involved in the combat against bacteria and their products. In addition, they express molecules that mediate the migration of polymorphonuclear leukocytes toward the bottom of the gingival sulcus. Periodontopathogens-such as Actinobacillus actinomycetemcomitans or, in particular, Porphyromonas gingivalis-have developed sophisticated methods to perturb the structural and functional integrity of the junctional epithelium. Research has focused on the direct effects of gingipains, cysteine proteinases produced by Porphyromonas gingivalis, on junctional epithelial cells. These virulence factors may specifically degrade components of the cell-to-cell contacts. This review will focus on the unique structural organization of the junctional epithelium, on the nature and functions of the various molecules expressed by its cells, and on how gingipains may attenuate the junctional epithelium's structural and functional integrity.

Lipopolysaccharide-Induced Epithelial Monoamine Oxidase Mediates Alveolar Bone Loss in a Rat Chronic Wound Model

“…Conversion of this biofilm to a Gram-negative, LPS-rich microbial population is associated with the conversion of the junctional to pocket epithelium, which is regarded as an early marker of disease initiation. 9 Periodontitis is associated with oxidative stress, 10 decreased total antioxidant status, 11 and/or increased lipid peroxidation in gingival crevicular fluid and saliva. 12 Experimentally induced periodontitis provides a valuable model of chronic wounds and alveolar bone loss.…”

Reparative Phase Events on Periodontal Disease Progression: Interpretation and Considerations

“…This occurrence allows in this unique healing site a communication between the underlying connective tissue and the contaminated, humid and warm oral environment as healing progresses. To prevent infection, epithelial proliferations extend apically on the tooth aspect, establishing a long junctional epithelium attached to the root surface by hemidesmosomes [47,48,49]. The long junctional epithelium is a fragile structural and functional adaptation enabled to produce a defensive biological mechanism, which is responsible to control the constant microbial challenge by isolating the exposed connective tissue in the inner surface of the wound from contaminated oral environment [49].…”

Biologic Width Around Dental Implants.

“…50-100 lm away), no blood vessels were found. 13,14 Further away from the implant surface and adjacent to the barrier (junctional) and sulcular epithelia, blood vessels were observed (Buser et al 1992). Thus, the number of blood vessels increased with increasing distance from the implant surface.…”