Cellular and collagen reference values of gingival and periodontal ligament tissues in rats: a pilot study.

Reference data are lacking on the periodontal ligament and the gingival tissue of the rat model, which would be useful for studies of new medical or biomaterial periodontal treatments. The objective of the current study was to propose cellular and collagen reference values of gingival and periodontal ligament tissues in rat, using a simple and reliable quantitative method after decalcification. Mandibular samples of ten adult Sprague-Dawley rats were used. Mild decalcification was carried out using ethylenediaminetetraacetic acid (EDTA) to preserve the morphology of tissues. Half of the samples were decalcified and the other half were not. The gingiva and the periodontal ligament were analyzed. Descriptive histology and computer-assisted image analysis were performed. The data showed that qualitatively, cellular and extracellular matrix morphologies were well preserved compared to non-decalcified periodontal soft tissue biopsies. Histomorphometrically, constitutive cellularity and the total amount of native collagen, collagen directionality and collagen anisotropy in both experimental conditions did not significantly differ. Taken together, these results suggested that EDTA decalcification did not negatively affect the studied endpoints. Moreover, this mild decalcification method allowed in situ maintenance of the periodontal soft and hard tissue integrity. The structural and compositional computerized assessment performed in the healthy periodontal soft tissue could provide reference values that will be required for future assessment on the effects of pathological, reparative and regenerative processes in rat periodontal soft tissues.

Analyzing Human Periodontal Soft Tissue Inflammation and Drug Responses In Vitro Using Epithelium-Capillary Interface On-a-Chip.

The gingival epithelium-capillary interface is a unique feature of periodontal soft tissue, preserving periodontal tissue homeostasis and preventing microorganism and toxic substances from entering the subepithelial tissue. However, the function of the interface is disturbed in periodontitis, and mechanisms of the breakdown of the interface are incompletely understood. To address these limitations, we developed a microfluidic epithelium-capillary barrier with a thin culture membrane (10 µm) that closely mimics the in vivo gingival epithelial barrier with an immune micro-environment. To test the validity of the fabricated gingival epithelial barrier model, epithelium-capillary interface-on-a-chip was cultured with human gingival epithelial cells (HGECs) and human vascular endothelial cells (HUVEC). Their key properties were tested using optical microscope, transepithelial/transendothelial electrical resistance (TEER), and permeability assays. The clear expression of VE-cadherin revealed the tight junctions in endothelial cells. Live/dead assays indicated a high cell viability, and the astrocytic morphology of HGE cells was confirmed by F-actin immunostaining. By the third day of cell culture, TEER levels typically exceeded in co-cultures. The resultant permeability coefficients showed a significant difference between 70 kDa and 40 kDa FITC-dextran. The expression of protein intercellular cell adhesion molecule (ICAM-1) and human beta defensin-2 (HBD2) decreased when exposed to TNF-α and LPS, but recovered with the NF-κB inhibitor treatment- Pyrrolidinedithiocarbamic acid (PDTC), indicating the stability of the fabricated chip. These results demonstrate that the developed epithelium-capillary interface system is a valid model for studying periodontal soft tissue function and drug delivery.

Correlation between periodontal soft tissue and hard tissue surrounding incisors in skeletal Class III patients.

OBJECTIVES: To investigate the association between the periodontal soft tissue, alveolar bone and dental parameters surrounding the incisors at baseline in patients with skeletal Class III malocclusion. MATERIALS AND METHODS: The study sample comprised 154 teeth from 28 patients with skeletal Class III malocclusion (19 men and 9 women, 21.15 ± 4.02 years). Periodontal soft tissue examination and hard tissue measurements with cone-beam computed tomography (CBCT) were performed. Factor analysis was used to reduce the CBCT variables, and correlation analysis between the hard tissue factors and soft tissue parameters was performed. Differences in hard tissue parameters between thick and thin gingival types were evaluated. RESULTS: CBCT measurements were reduced to three hard tissue factors: lingual plate, coronal-buccal plate, and apical-buccal plate. Keratinized gingiva width and thickness were positively correlated with the coronal-buccal plate factor and negatively correlated with the apical-buccal plate factor. In the thin gingival biotype, mandibular incisors were more proclined, and the apical part of the buccal alveolar plate and the coronal part of lingual alveolar plate were thicker than in the thick gingival biotype. CONCLUSIONS: In the anterior teeth in cases of skeletal Class III malocclusion, hard tissue structures on the buccal side can be grouped based on coronal and apical factors that are significantly correlated with keratinized gingival width and thickness. Thick and thin gingival biotypes exhibited differences in tooth inclination and alveolar plate thickness with regard to the mandibular incisors.