3D engineered human gingiva fabricated with electrospun collagen scaffolds provides a platform for in vitro analysis of gingival seal to abutment materials.

In order to advance models of human oral mucosa towards routine use, these models must faithfully mimic the native tissue structure while also being scalable and cost efficient. The goal of this study was to develop a low-cost, keratinized human gingival model with high fidelity to human attached gingiva and demonstrate its utility for studying the implant-tissue interface. Primary human gingival fibroblasts (HGF) and keratinocytes (HGK) were isolated from clinically healthy gingival biopsies. Four matrices, electrospun collagen (ES), decellularized dermis (DD), type I collagen gels (Gel) and released type I collagen gels (Gel-R)) were tested to engineer lamina propria and gingiva. HGF viability was similar in all matrices except for Gel-R, which was significantly decreased. Cell penetration was largely limited to the top layers of all matrices. Histomorphometrically, engineered human gingiva was found to have similar appearance to the native normal human gingiva except absence of rete pegs. Immunohistochemical staining for cell phenotype, differentiation and extracellular matrix composition and organization within 3D engineered gingiva made with electrospun collagen was mostly in agreement with normal gingival tissue staining. Additionally, five types of dental material posts (5-mm diameter x 3-mm height) with different surface characteristics were used [machined titanium, SLA (sandblasted-acid etched) titanium, TiN-coated (titanium nitride-coated) titanium, ceramic, and PEEK (Polyetheretherketone) to investigate peri-implant soft tissue attachment studied by histology and SEM. Engineered epithelial and stromal tissue migration to the implant-gingival tissue interface was observed in machined, SLA, ceramic, and PEEK groups, while TiN was lacking attachment. Taken together, the results suggest that electrospun collagen scaffolds provide a scalable, reproducible and cost-effective lamina propria and 3D engineered gingiva that can be used to explore biomaterial-soft tissue interface.

Does simultaneous soft tissue augmentation around immediate or delayed dental implant placement using sub-epithelial connective tissue graft provide better outcomes compared to other treatment options? A systematic review and meta-analysis.

OBJECTIVE: The clinical benefits of simultaneous implant placement and soft tissue augmentation using different treatment modalities are unclear. The current meta-analysis aimed to compare the effect of simultaneous soft tissue augmentation using subepithelial connective tissue graft (SCTG) around immediate or delayed dental implant placement with other treatment modalities on the peri-implant tissue health and esthetic. METHODS: Up to May 2021, four databases (PubMed, EMBASE, Cochrane Central, and Google Scholar) were searched. Randomized control trials with follow-up >3 months, evaluating simultaneous implant placement (immediate or delayed) and soft tissue augmentation using SCTG compared with other treatment modalities were included. The predictor variables were SCTG versus no augmentation with/without guided bone regeneration (GBR) or other augmentation techniques (Acellular dermal matrix (ADM), Xenogeneic collagen matrix (XCM). The outcome variables were buccal tissue thickness (BTT), mid-buccal gingival level (MGL), marginal bone loss (MBL), and pink esthetic scores (PES). Cumulative mean differences (MD) and 95% confidence interval (CI) were estimated. RESULTS: Twelve studies were included. SCTG along with immediate implant placement (IIP) or delayed implant placement (DIP) showed a statistically significant improvement in BTT (Fixed; MD, 0.74; 95% CI, 0.51; 0.97), MGL (Fixed; MD, 0.5; 95% CI, 0.21; 0.80), PES (Fixed; MD, 0.79; 95% CI, 0.29; 1.29), and less MBL (Fixed; MD, -0.11; 95% CI, -0.14; -0.08) compared to no graft (P<0.05). A statistically insignificant differences in BTT (Random; MD, 0.62; 95% CI, -0.41; 1.65), MGL (Fixed; MD, -0.06; 95% CI, -0.23; 0.11), MBL (Fixed; MD, 0.36; 95% CI, -0.05; 0.77) and PES (Fixed; MD, 0.28; 95% CI, -0.10; 0.67) was observed when SCTG along with DIP was compared with no augmentation plus GBR. Similarly, no statistically significant difference was observed when comparing SCTG along with DIP with acellular dermal matrix (ADM) concerning BTT (MD:0.71, P = 0.18) and KMW (MD: 0.6, P = 0.19). CONCLUSION: There is a very low quality of evidence to provide recommendations on whether simultaneous dental implant placement (IIP or DIP) and soft tissue augmentation using SCTG is superior to no augmentation or is comparable to the other tissue augmentation materials in improving the quality and quantity of peri-implant tissues. Therefore, further, well-designed RCTs with larger sample sizes and long follow-up times are still needed.

Maxillary anterior gingiva and dentoalveolar changes after en-masse retraction between thick and thin gingival biotypes.

INTRODUCTION: This study compared the changes of gingiva and alveolar bone parameters, including cortical and cancellous bones between thick and thin gingival biotypes after en-masse retraction. METHODS: Thirty-two adult subjects (mean age, 20.6 years) with maxillary anterior teeth protrusion and proclination were studied and divided into 2 equal groups: thick gingival biotype (TKB) and thin gingival biotype (TNB). Maxillary anterior teeth were retracted using nickel-titanium coil springs at 150 g of force bilaterally for 4 months. Lateral cephalograms, study models, and cone-beam computed tomography scans were taken before retraction and 3 months after 4 months of retraction. Nonparametric tests compared the changes within the groups at these periods and between the groups. RESULTS: The gingiva gained thickness and length (P <0.01) on the labial and palatal sides. The gingival thickness gained more on the palatal side (P <0.01), whereas the length gained equally in both groups. Labial alveolar bone showed increased thickness and height (P <0.01) as opposed to the palatal alveolar bone that presented with loss of thickness and height (P <0.01). The height loss occurred more in TNB (P <0.01). Labial cortical bone increased in thickness and height (P <0.01), whereas palatal cortical bone thinned (P <0.01) at levels in which no cancellous bone was present at the crestal level for TKB and the crestal and midroot levels for TNB. TKB showed slower incisor movement and less retroclination than the TNB (P <0.01) with minimal incisor extrusion. CONCLUSIONS: Favorable gingiva and labial bone responses after en-masse retraction were found in both gingival biotypes, whereas more palatal alveolar bone height loss was presented in TNB. Cortical bone thickness decreased when cancellous bone was absent.

Characterization of the foreign body response of titanium implants modified with polyphenolic coatings.

The foreign body response is dictating the outcome of wound healing around any implanted materials. Patients who suffer from chronic inflammatory diseases and impaired wound healing often face a higher risk for implant failure. Therefore, functional surfaces need to be developed to improve tissue integration. For this purpose, we evaluated the impact of surface coatings made of antioxidant polyphenolic molecules tannic acid (TA) and pyrogallol (PG) on the host response in human blood. Our results showed that although the polyphenolic surface modifications impact the initial blood protein adsorption compared to Ti, the complement and coagulation systems are triggered. Despite complement activation, monocytes and granulocytes remained inactivated, which was manifested in a low pro-inflammatory cytokine expression. Under oxidative stress, both coatings were able to reduce intracellular reactive oxygen species in human gingival fibroblasts (hGFs). However, no anti-inflammatory effects of polyphenolic coatings could be verified in hGFs stimulated with lipopolysaccharide and IL-1ß. Although polyphenols reportedly inhibit the NF-κB signaling pathway, phosphorylation of NF-κB p65 was observed. In conclusion, our results indicated that TA and PG coatings improved the hemocompatibility of titanium surfaces and have the potential to reduce oxidative stress during wound healing.

Intracellular glucose starvation affects gingival homeostasis and autophagy.

Human gingival fibroblasts (HGnFs) maintain periodontal tissue homeostasis through active proliferation and migration. Clinically, it is considered that the wound-healing ability of the gingival tissue is maintained even in environments with insufficient supply of nutrients, such as glucose, immediately after periodontal surgery. However, the effects of such glucose-deficient environments on HGnFs remain unclear. This study aimed to investigate the effects of low-glucose environment on HGnFs homeostasis. We evaluated gingival wound healing by examining cell proliferation and migration and collagen synthesis in HGnFs cultured in 100, 50, 25, and 0 mg/dL glucose in vitro. The cellular stress levels were determined by measuring the lactate dehydrogenase (LDH) and reactive oxygen species (ROS) levels. The glucose metabolism of HGnFs in the low-glucose concentrations was studied by measuring glucose transporter type 1 (GLUT1) mRNA expression, glucose uptake assays, lactate and ATP productions. Molecular effects were examined with a focus on the LKB1-AMPK signaling pathway. Autophagy activity in glucose-deprived HGnFs was evaluated by measuring the levels of autophagy-related proteins. Low glucose levels increased cellular stress levels, autophagy activity, and enhanced glucose metabolism through the LKB1-AMPK signaling pathway, providing more ATPs to promote wound healing. Our results regarding glucose transfer suggest the rapid healing of gingival wounds.

Investigating the role of gingiva in the tactile function of teeth at the cortical level.

The role of the gingiva in the tactile perception of teeth is unclear, and the physiological basis of tooth tactile function needs to be examined at the cortical response level. In the presented study, gingiva from the upper left canine was removed under local anesthesia from five cats. Intrinsic signal optical imaging was used to measure population response characteristics of the cat oral-related cortex when punctate mechanical stimuli were separately applied to the left gingiva-stripped canine and right intact canine. Then, their response characteristics were compared. There were no significant differences in the cortical response strength between the anesthetized and unanesthetized canines. Signal strength of the gingiva-stripped tooth was significantly weaker than that of the intact tooth at low stimulus strength. However, no significant differences between the gingiva-stripped tooth and intact tooth were found after saturation. Based on the evoked cortical responses, the gingiva is involved in low-intensity tactile perception of teeth, which could explain the reason why chronic gingivitis results in the paresthesia of natural teeth.

PCR array analysis identified hyperproliferation but not autophagy or apoptosis in fibrous epulis.

BACKGROUND: The pathogenesis of fibrous epulis is still quite unclear. Our recent genome-wide RNA sequencing analysis revealed that in fibrous epulis, RAS-PI3K-AKT-NF-κB pathway regulates the expression of Bcl-2 family and IAP family genes, leading to increased proliferation and the inhibition of apoptosis. The PI3K/AKT signaling pathway can promote autophagy in human gingival fibroblasts; therefore, the purpose of the present study was to identify whether autophagy is involved in the pathogenesis of fibrous epulis. METHODS: Differentially expressed genes (DEGs) between fibrous epulis lesions and normal gingival tissues were identified using the PCR array. The expression levels of eighteen autophagy-related (ATG) family genes, twelve B-cell lymphoma 2 (Bcl-2) family genes, and eleven cysteine-dependent aspartate-directed protease (caspase) family genes were validated using quantitative real-time PCR (qRT-PCR). Autophagy induction was determined by measuring microtubule-associated protein light chain 3 (LC3) conversion (LC3-I to LC3-II) by immunoblot analysis. RESULTS: The PCR array identified six upregulated genes, whereas no genes were expressed at significantly lower levels. The upregulated genes were BCL2, BCL2L1, CXCR4, HSP90AA1, HSPA8, and IGF1, which all belong to the "regulation of autophagy" group but not the "autophagy machinery components" group. qRT-PCR verified that the expression levels of BCL2, BCL2L1 (also known as BCL-XL), and BCL2L2 (also known as BCL-W) were significantly increased in fibrous epulis. No LC3-I to LC3-II conversion was observed. CONCLUSIONS: The present study reveals that in fibrous epulis, Bcl-2 and Bcl-xL coordinately mediate gingival cell escape from apoptosis, leading to uncontrolled proliferation. Moreover, ATG family genes are not activated, and autophagy is not involved in this process.

Defining human mesenchymal and epithelial heterogeneity in response to oral inflammatory disease.

Human oral soft tissues provide the first barrier of defence against chronic inflammatory disease and hold a remarkable scarless wounding phenotype. Tissue homeostasis requires coordinated actions of epithelial, mesenchymal, and immune cells. However, the extent of heterogeneity within the human oral mucosa and how tissue cell types are affected during the course of disease progression is unknown. Using single-cell transcriptome profiling we reveal a striking remodelling of the epithelial and mesenchymal niches with a decrease in functional populations that are linked to the aetiology of the disease. Analysis of ligand-receptor interaction pairs identify potential intercellular hubs driving the inflammatory component of the disease. Our work establishes a reference map of the human oral mucosa in health and disease, and a framework for the development of new therapeutic strategies.

Oral microbiome interactions with gingival gene expression patterns for apoptosis, autophagy and hypoxia pathways in progressing periodontitis.

Oral mucosal tissues must react with and respond to microbes comprising the oral microbiome ecology. This study examined the interaction of the microbiome with transcriptomic footprints of apoptosis, autophagy and hypoxia pathways during periodontitis. Adult Macaca mulatta (n = 18; 12-23 years of age) exhibiting a healthy periodontium at baseline were used to induce progressing periodontitis through ligature placement around premolar/molar teeth. Gingival tissue samples collected at baseline, 0·5, 1 and 3 months of disease and at 5 months for disease resolution were analysed via microarray. Bacterial samples were collected at identical sites to the host tissues and analysed using MiSeq. Significant changes in apoptosis and hypoxia gene expression occurred with initiation of disease, while autophagy gene changes generally emerged later in disease progression samples. These interlinked pathways contributing to cellular homeostasis showed significant correlations between altered gene expression profiles in apoptosis, autophagy and hypoxia with groups of genes correlated in different directions across health and disease samples. Bacterial complexes were identified that correlated significantly with profiles of host genes in health, disease and resolution for each pathway. These relationships were more robust in health and resolution samples, with less bacterial complex diversity during disease. Using these pathways as cellular responses to stress in the local periodontal environment, the data are consistent with the concept of dysbiosis at the functional genomics level. It appears that the same bacteria in a healthy microbiome may be interfacing with host cells differently than in a disease lesion site and contributing to the tissue destructive processes.

γδ T cells in tissue physiology and surveillance.

γδ T cells are a unique T cell subpopulation that are rare in secondary lymphoid organs but enriched in many peripheral tissues, such as the skin, intestines and lungs. By rapidly producing large amounts of cytokines, γδ T cells make key contributions to immune responses in these tissues. In addition to their immune surveillance activities, recent reports have unravelled exciting new roles for γδ T cells in steady-state tissue physiology, with functions ranging from the regulation of thermogenesis in adipose tissue to the control of neuronal synaptic plasticity in the central nervous system. Here, we review the roles of γδ T cells in tissue homeostasis and in surveillance of infection, aiming to illustrate their major impact on tissue integrity, tissue repair and immune protection.

Electronic cigarette liquid substances propylene glycol and vegetable glycerin induce an inflammatory response in gingival epithelial cells.

Information on the effects of propylene glycol (PG) and vegetable glycerin (VG) and on cytotoxicity and subsequent activation of the biological mediators is limited in periodontal diseases. This study analyzes the effect of unflavored PG/VG alone or in combination with nicotine on gingival epithelial cells. The cells were exposed to different PG/VG (± nicotine) concentrations for 24 h and cytotoxicity was evaluated by calorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromid assay. The expressions of interleukin (IL)-6, IL-8, and matrix metalloproteinases (MMPs)-9 were measured using an enzyme-linked immunosorbent assay and a western blotting. Stimulation with PG/VG mixtures reduced cell viability compared to nonexposed controls (p < 0.05). Adding PG/VG increased the levels of IL-6, IL-8, and MMP-9, and the amount of PG had more biological impact compared to the VG amount. The nicotine augmented this effect compared to its nicotine-free counterparts. In western blotting result, MMP-9 was clearly activated in almost all samples. These findings suggest that the main constituents PG/VG are cytotoxic and able to induce biological response in gingival cells in vitro. Despite being advertised as less harmful than conventional cigarettes, electronic cigarette liquid pose certain risks on periodontal cells. Awareness about the effects of electronic cigarettes on periodontal diseases must be increased.

Effect of Direct and Indirect Materials on Stress Distribution in Class II MOD Restorations: A 3D-Finite Element Analysis Study.

The aim of this study is to investigate the stress distributions of different restoration options for class II mesio-occluso-distal (MOD) cavities. A class II MOD cavity with proximal box gingival floor 1 mm below cementoenamel junction was designed in a mandibular first molar tooth model. 3D finite-element analysis (FEA) and 3D-CAD modelling were used to examine the occlusal stresses distributed to the remaining buccal enamel (RBE), remaining lingual enamel (RLE), adhesive surfaces, and restorative materials by direct and indirect materials resulting from a 600 N of static occlusal load stimulating foodstuff. von Mises (VM) and maximum principal (Pmax) stresses were evaluated for two CAD/CAM materials and three direct materials. CAD/CAM materials exerted less stress than the direct restorative materials. Significant von Mises and Pmax stress value differences were seen among all restoration models on RBE. Reducing RLE and including it into the cavity would be a more effective option for this model in this scenario. As VM and Pmax stresses of PIHC CAD/CAM material for RBE and dentin were significantly lower than other tested materials, it may be the choice of material for indirect MOD restorations.

Gingival epithelium attachment to well- or partially cured resin composites.

Ideal restoration material for caries would allow attachment of gingival epithelia. The attachment of epithelial cells to specimens of the 4 most commercially used well- or partially-cured resin composites, with and without TEGDMA, was assessed. Effects of resin composite on the Ca9-22 gingival epithelial cell-line were assessed by measuring the cytotoxicity, viability and gene expression for attachment, apoptosis, ROS-production, pro-inflammatory cytokines, and matrix metalloproteinases. As controls, cells on tissue culture plastic or bovine tooth enamel specimens were used. Significantly less cell attachment was measured on freshly made resin-composite specimens. Concomitantly, significantly higher cytotoxicity was measured in the presence of freshly made resin-composite specimens. However, after 8 d of leakage, the cell attachment to and cytotoxicity of the resin composite was comparable to bovine tooth enamel. Significantly higher expressions of IL6, MMP2, BCL6 and ITGA4 were measured in cells attached to resin-composite surfaces than controls. There were no significant differences between the results using different conditions of resin composite, with or without TEGDMA and well or partially cured. Less cell attachment and presence of more inflammatory markers were observed on all freshly-made resin-composite surfaces. However, after a leakage period attachment of cells to the resin composite improved to the level of natural tooth materials such as enamel. This indicated that the negative effects of resin composites on epithelial cells might be transient.

Gingival Response to Dental Implant: Comparison Study on the Effects of New Nanopored Laser-Treated vs. Traditional Healing Abutments.

The health of peri-implant soft tissues is important for the long-term success rate of dental implants and the surface topography is pivotal in influencing it. Thus, the aim of this study was to evaluate, in human patients, the inflammatory mucosal microenvironment in the tissue surrounding a new, nanoscale, laser-treated healing abutment characterized by engineered nanopores versus a standard machined-surface. Analyses of anti- and pro-inflammatory markers, cytokeratins, desmosomal proteins and scanning electron microscopy were performed in 30 soft-tissue biopsies retrieved during second-stage surgery. The results demonstrate that the soft tissue surrounding the laser-treated surface was characterized by a lower grade of inflammation than the one facing the machined-surface, which, in turn, showed a disrupted epithelium and altered desmosomes. Moreover, higher adhesion of the epithelial cells on the laser-treated surface was detected compared to the machined one. In conclusion, the laser-treated surface topography seems to play an important role not only in cell adhesion, but also on the inflammatory makers' expression of the soft tissue microenvironment. Thus, from a clinical point of view, the use of this kind of topography may be of crucial importance not only on healing abutments but also on prosthetic ones.

Evaluation of the In Vitro Oral Wound Healing Effects of Pomegranate (Punica granatum) Rind Extract and Punicalagin, in Combination with Zn (II).

Pomegranate (Punica granatum) is a well-established folklore medicine, demonstrating benefits in treating numerous conditions partly due to its antimicrobial and anti-inflammatory properties. Such desirable medicinal capabilities are attributed to a high hydrolysable tannin content, especially punicalagin. However, few studies have evaluated the abilities of pomegranate to promote oral healing, during situations such as periodontal disease or trauma. Therefore, this study evaluated the antioxidant and in vitro gingival wound healing effects of pomegranate rind extract (PRE) and punicalagin, alone and in combination with Zn (II). In vitro antioxidant activities were studied using DPPH and ABTS assays, with total PRE phenolic content measured by Folin-Ciocalteu assay. PRE, punicalagin and Zn (II) combination effects on human gingival fibroblast viability/proliferation and migration were investigated by MTT assay and scratch wounds, respectively. Punicalagin demonstrated superior antioxidant capacities to PRE, although Zn (II) exerted no additional influences. PRE, punicalagin and Zn (II) reduced gingival fibroblast viability and migration at high concentrations, but retained viability at lower concentrations without Zn (II). Fibroblast speed and distance travelled during migration were also enhanced by punicalagin with Zn (II) at low concentrations. Therefore, punicalagin in combination with Zn (II) may promote certain anti-inflammatory and fibroblast responses to aid oral healing.

Mechanical properties of human oral mucosa tissues are site dependent: A combined biomechanical, histological and ultrastructural approach.

AIM: To investigate load-deformation properties of Thiel-embalmed human oral mucosa tissues and to compare three different anatomical regions in terms of mechanical, histological and ultrastructural characteristic with focus on the extracellular matrix. MATERIALS AND METHODS: Thirty specimens from three different regions of the oral cavity: attached gingiva, buccal mucosa and the hard palate were harvested from two Thiel-embalmed cadavers. Mechanical properties were obtained, combining strain evaluation and digital image correlation in a standardised approach. Elastic modulus, tensile strength, strain at maximum load and strain to failure were computed and analysed statistically. Subsamples were also analysed using scanning electron microscopy (SEM) and histological analysis. RESULTS: The highest elastic modulus of 37.36 ± 17.4 MPa was found in the attached gingiva group, followed by the hard palate and buccal mucosa. The elastic moduli of attached gingiva differed significantly to the buccal mucosa (p = .01) and hard palate (p = .021). However, there was no difference in the elastic moduli between the buccal mucosa and hard palate (p > .22). The tensile strength of the tissue samples ranged from 1.54 ± 0.5MPa to 3.81 ± 0.9 MPa, with a significant difference between gingiva group and buccal mucosa or hard palate (p = .001). No difference was found in the mean tensile strength between the buccal mucosa and hard palate (p = .92). Ultrastructural imaging yielded a morphological basis for the various mechanical properties found intraorally; the attached gingiva showed unidirectional collagen fibre network whereas the buccal mucosa and hard palate showed multi-directional network, which was more prone to tension failure and less elasticity. CONCLUSION: This is the first study assessing the various morphological-mechanical relationships of intraoral soft tissues, utilising Thiel-embalmed tissues. The findings of this study suggest that the tissues from different intraoral regions showed various morphological-mechanical behaviour which was also confirmed under the SEM and in the histological analysis.

Concentrated growth factor promotes gingival regeneration through the AKT/Wnt/ß-catenin and YAP signaling pathways.

Although concentrated growth factor (CGF) is known to promote gingival regeneration and improve the outcomes of clinical treatment, the mechanisms underlying its effects remain unknown. Therefore, this study aimed to elucidate the effects of CGF on gingival thickening. To this end, gingival mesenchymal stem cells (GMSCs) were treated with different concentrations of CGF, and the effects of CGF on cell proliferation and migration; collagen-1 (Col-1), fibronectin (FN), vascular endothelial growth factor (VEGF), and angiopoietin-1 (Ang-1) expression; and the AKT, Wnt/ß-catenin, and Yes-associated protein (YAP) signalling pathways were investigated. The effects of CGF in vivo were also investigated in a rat buccal gingival injection model. GMSCs cultured with CGF showed improved cell proliferation and migration. Moreover, CGF treatment improved the levels of FN, Col-1, VEGF, and ANG-1. These effects of CGF were mediated by the AKT/Wnt and YAP pathways, with the AKT pathway possibly functioning upstream of the Wnt/ß-catenin and YAP pathways. YAP was also shown to be overexpressed in the in vivo model. Thus, CGF can promote gingival regeneration, and YAP transport into the nucleus may be a key factor underlying this activity, which provides a novel perspective for gingival regeneration and further promotion of the clinical application of CGF.

Photobiomodulation with 808-nm diode laser enhances gingival wound healing by promoting migration of human gingival mesenchymal stem cells via ROS/JNK/NF-κB/MMP-1 pathway.

Photobiomodulation (PBM) has been shown to improve wound healing by promoting mesenchymal stem cell migration and proliferation. However, it remains unknown whether an 808-nm diode laser can influence human gingival mesenchymal stem cells (HGMSCs), and which dose this works well. In the present study, it was found that PBM could promote the migration of HGMSCs but not the proliferation. Furthermore, PBM could activate mitochondrial ROS, which could elevate the phosphorylation levels of JNK and IKB in HGMSCs, and further activate NF-κB as the nuclear translocation of p65 is elevated. Taken together, these present results indicate that PBM might promote cell migration via the ROS/JNK/NF-κB pathway.

Effect of physical stimulation (gingival massage) on age-related changes in gingival microcirculation.

The decline in circulatory function with aging may be alleviated by a combination of gingival massage (physical stimulation) and mechanical cleaning. Several studies have reported the systemic effect of physical stimulation on various parts of the body, including its therapeutic effect on pain in the neck and shoulders that becomes evident with age, and improvement in blood circulation. In contrast, few studies have reported on the changes in gingival microcirculation induced by gingival massage, while no previous study has evaluated the effect of gingival microcirculation on age-related changes in the hemodynamics of the oral cavity. This study aimed to investigate how gingival massage affects age-related changes in gingival microcirculation. Male Wistar rats (7-week, 6-month and 1-year old) were prepared for a gingival massage group and a control group. Mechanical stimulation was applied on the maxillary molar gingiva for 5 seconds twice a week for 4 weeks. Subsequently, gingival reactive hyperemia was measured using a laser Doppler flowmeter. In addition, morphological analyses were also performed by hematoxylin and eosin and Indian ink staining and a vascular resin cast model. Base Flow, maximum response (Peak), and time required for the maximum response to halve (T1/2) were reduced in 1-year-old rats compared with the other age groups. In the mechanical stimulated group, T1/2 was increased in 7-week, 6-month, and 1-year-old rats, and total blood flow (Mass) was increased in 6-month and 1-year-old rats. In addition, clear blood vessel networks and loop-like revascularization were only observed in the mechanical stimulated group. Changes in age-related decline in gingival microcirculatory function and vascular construction were reported in this study, and the results suggested that gingival massage activates both the functional and morphological aspects of gingival microcirculation and may be effective for maintaining oral health.