Human Periodontal Fibroblasts Research Articles

SARS-CoV-2 infection causes periodontal fibrotic pathogenesis through deregulating mitochondrial beta-oxidation

The global high prevalence of COVID-19 is a major challenge for health professionals and patients. SARS-CoV-2 virus has four structural protein components: the spike protein, envelope protein, membrane protein, and nucleocapsid protein. The SARS-CoV-2 virus mutates predominantly in the spike proteins, whilst the other key viral components usually remain stable. Essentially the pathological functions of the SARS-CoV-2 virus on different cell types are still largely unknown. Previous studies have shown that the human oral cavity can potentially act as reservoir of the SARS-CoV-2 virus. However, the consequence of SARS-CoV-2 viral infection on human oral health has not been systematically examined. COVID-19 can cause severe oral mucosa lesions and is likely to be connected with poor periodontal conditions. Fibroblasts are the major cell type inside periodontal ligament (PDL) and express the SARS-CoV-2 receptor: Angiotensin-converting enzyme 2 (ACE2), whose expression level can increase upon bacterial infection hence potentially provide a direct route of SARS-CoV-2 infection to PDL fibroblasts. In this research, we aimed to study the pathogenicity of SARS-CoV-2 viral components on human fibroblasts. We found that by exposing to SARS-CoV-2, especially to the viral envelope and membrane proteins, the human periodontal fibroblasts could develop fibrotic pathogenic phenotypes, including hyperproliferation that was simultaneously induced with increased apoptosis and senescence. The fibrotic degeneration was mediated by a down-regulation of mitochondrial β-oxidation in the fibroblasts. Fatty acid β-oxidation inhibitor, etomoxir treatment could mirror the same pathological consequence on the cells, similar to SARS-CoV-2 infection. Our results therefore provide novel mechanistic insights into how SARS-CoV-2 infection can affect human periodontal health at the cell and molecular level with potential new therapeutic targets for COVID-19 induced fibrosis.

Regulation of TGF-β1 on human periodontal fibroblasts in inflammatory state

Regulation of TGF-β1 on human periodontal fibroblasts in inflammatory state

Isoimperatorin alleviates lipopolysaccharide-induced periodontitis by downregulating ERK1/2 and NF-κB pathways.

Chronic periodontitis is an inflammatory disease characterized by inflammation of the soft tissues of the gums. To combat this disease, more effective drugs are still needed to identify and develop. Isoimperatorin is a kind of a natural compound, which has anti-inflammatory, analgesic, antitumor, antivirus, and other pharmacological effects. However, its possible effects on the progression of chronic periodontitis are still unclear. In this study, we used human periodontal membrane fibroblasts (hPDLCs), human bone marrow-derived macrophages, and found that isoimperatorin reduced hPDLCs viability. In addition, isoimperatorin alleviated the oxidative stress of periodontal membrane cells. Isoimperatorin reduced proinflammatory factor secretion and receptor activator for nuclear factor-κB ligand-induced osteoclast differentiation in periodontal membrane cells. Further, isoimperatorin inhibited the activation of ERK1/2 and nuclear factor-κB pathways. We, therefore, thought isoimperatorin could serve as a promising drug for the treatment of this disease.

"Efficacy of cytotoxic effect of green tea catechins on the human periodontal fibroblasts and human dental pulp fibroblasts -An in vitro study".

Inflammation of tooth-supporting tissue and the pulp tissue is followed by wound healing and regeneration process that involves the specific type of connective tissue cells, the fibroblasts. During periodontitis and pulpitis, the inflammation of the tissue causes damage to the fibroblasts. These fibroblasts secrete collagen proteins and maintain the structural framework; along with this the inflammatory process moves toward healing where in the specific cells such as the fibroblast cells play important roles. Green tea catechins epigallocatechin-3-gallate (EGCG) being one of the major catechins is known to have multiple beneficial effects on human fibroblasts. To assess the in vitro cytotoxicity of green tea catechins on the human periodontal ligament (PDL) fibroblasts and human dental pulp fibroblasts. Human PDL fibroblasts (hPDLFs) and human dental pulp fibroblasts were isolated from the two extracted premolar teeth that were indicated for orthodontic treatment. The fibroblasts were then seeded in 96 well tissue culture plate for cell viability study. EGCG was used at different concentration to treat the cells. After 48 h; (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) (MTT) assay was performed to determine the cell viability. The vitality of hPDLFs and human dental pulp fibroblasts was found to be inversely proportional to EGCG concentrations. hPDLFs have shown 37% proliferation at lowest concentration of EGCG used and human dental pulp fibroblasts have shown 99% viability at lowest concentration of EGCG used.

Comparison of a new thermosensitive rhAm carrier versus traditional PGA carrier for in vitro antibacterial activity and biocompatibility

To compare a new thermosensitive recombinant human amelogenin (rhAm) carrier and traditional propylene glycol alginate (PGA) carrier for their characteristics, antibacterial activity, and biocompatibility with human periodontal membrane fibroblasts. PGA-rhAm was prepared by mixing 3.3% PGA and rhAm, and CS-βGP-rhAm was prepared by mixing 2% chitosan (CS) with rhAm and then with 60% β-sodium glycerophosphate solution (βGP) as the crosslinking agent. The biophysical properties of the prepared carriers were characterized, and their antibacterial activity was assessed by observing Staphylococcus aureus growth. The biocompatibility of the carriers was evaluated in human periodontal membrane fibroblasts (hPDLFs) using CCK8 assay and scratch test, and mRNA and protein expressions of osteogenic genes of the cells incubated with the carriers were detected using RT-qPCR and Western blotting; osteogenic differentiation of the cells was detected using alkaline phosphatase staining. PGA-rhAm had a viscosity value of 3.262±0.055 Pa.s. CS-βGP-rhAm had a solidification capacity of 6 min at 37 ℃ with a pH value close to that of the oral cavity and a swelling rate of about 90%. CS-β GP-rhAm maintained sustained release of rhAm for over 2 weeks with a self-degradation time over 3 weeks. CS-βGPrhAm more effectively inhibited the growth of S. aureus than rhAm-loaded PGA. While PGA did not obviously affect the proliferation of hPDLFs, both CS-βGP and CS-βGP-rhAm significantly promoted the cell proliferation(P < 0.001). Scratch test showed that after rhAm loading, both CS-βGP and PGA promoted cell migration (P < 0.01). CS-βGP-rhAm significantly enhanced the mRNA expressions of RUNX2 and OCN mRNA level and the protein expressions of Ki67, RUNX2, collagen I, and β-catenin (P < 0.05); PGA-rhAm only enhanced RUNX2 (P < 0.05) and OCN (P < 0.01) mRNA expressions without significant effects on the protein expressions. Alkaline phosphatase staining results showed that CS-βGP, but not PGA, promoted osteogenic differentiation of hPDLFs. CS-βGP carrier is capable of sustained release of rhAm, inhibiting the growth of S. aureus, and improving the biological activity of hPDLFs without affecting the bioactivity of rhAm after drug loading.

Platelet-derived growth factor-BB regenerates functional periodontal ligament in the tooth replantation

Tooth ankylosis is a pathological condition of periodontal ligament (PDL) restoration after tooth replantation. Platelet-derived growth factor-BB (PDGF-BB) has been proposed as a promising factor for preventing tooth ankylosis. Using rat tooth replantation model, we investigated whether PDGF-BB accelerates the repair of PDL after tooth replantation without ankylosis, and its molecular mechanisms. In PDGF-BB pretreated replanted teeth (PDGF-BB group), ankylosis was markedly reduced and functionally organized PDL collagen fibers were restored; the mechanical strength of the healing PDL was restored to an average of 76% of that in non-replanted normal teeth at 21 days. The numbers of PDGF-Rβ- and BrdU-positive cells in the periodontal tissues of the PDGF-BB group were greater than those of atelocollagen pretreated replanted teeth (AC group). Moreover, in the PDGF-BB group, the periodontal tissues had fewer osteocalcin-positive cells and decreased number of nuclear β-catenin-positive cells compared to those in the AC group. In vitro analyses showed that PDGF-BB increased the proliferation and migration of human periodontal fibroblasts. PDGF-BB downregulated mRNA expressions of RUNX2 and ALP, and inhibited upregulatory effects of Wnt3a on β-catenin, AXIN2, RUNX2, COL1A1, and ALP mRNA expressions. These findings indicate that in tooth replantation, topical PDGF-BB treatment enhances cell proliferation and migration, and inhibits canonical Wnt signaling activation in bone-tooth ankylosis, leading to occlusal loading of the PDL tissues and subsequent functional restoration of the healing PDL. This suggests a possible clinical application of PDGF-BB to reduce ankylosis after tooth replantation and promote proper regeneration of PDL.

CTHRC1 expressed in periodontitis and human periodontal fibroblasts exposed to inflammatory stimuli.

Collagen triple helix repeat containing-1 (CTHRC1) is a glycoprotein that can be secreted extracellularly and is involved in the regulation of collagen matrix in a variety of diseases. The expression level of CTHRC1 in periodontitis was detected in this study. The gingival tissues from clinically healthy subjects (15 cases) and those with periodontitis (30 cases) were taken for immunohistochemical staining. Lipopolysaccharide of the Porphyromonas gingivalis was added in the periodontal ligament fibroblast culture in vitro. Cells were collected, and the mRNA levels of the intracellular CTHRC1 and protein expression of the extracellular CTHRC1 were detected. The protein expression of CTHRC1 in the periodontitis group was higher than that of the clinically healthy group. The in vitro cell experiments showed that 10μg/ml of P.g LPS could induce a significant increase in protein secretion of CTHRC1, and 5μg/ml P.g LPS had a significant effect on promoting the mRNA expression of CTHRC1. Collagen triple helix repeat containing-1might be involved in the development of periodontitis, and the expression level might be significantly correlated with the stimulation of P.g LPS on fibroblasts. Different stimulation intensities of P.g LPS might result in different expression patterns of CTHRC1.

Role of cytochrome P450 2C8 genetic polymorphism and epoxygenase uncoupling in periodontal remodelling affecting orthodontic treatment.

In genome-wide association studies, the CYP2C8 gene locus has been reported to be associated with bisphosphonate-related osteonecrosis of the jaw, a severe devastating side effect of antiresorptive bone treatment. The aim of this study was to elucidate the putative pathomechanism explaining the association between the genetic polymorphism with the alleles CYP2C8*2 and *3 causing low CYP2C8 activity, and disturbed periodontal remodelling in periodontal fibroblasts cultured from patients undergoing orthodontic treatment. CYP2C8 activity, enzyme expression and substrate metabolism were detected in human periodontal fibroblast cultures. Zoledronic acid caused enhanced reactive oxygen species (ROS) production in periodontal fibroblasts, which was enhanced by arachidonic acid as inflammatory signal. Enhanced bisphosphonate-induced uncoupling of the CYP2C8 enzyme was detected in the variant allele (CYP2C8*3) with the result of increased H2 O2 production and lowered substrate oxidation. Conversely, substrate (amodiaquine) addition led to decreased H2 O2 production in isolated CYP2C8 enzymes, but in CYP2C8*3 enzyme, increased H2 O2 was still detected, especially in presence of arachidonic acid. CYP2C8 variants leading to decreased enzyme activity in substrate oxidation may enhance ROS production by reaction uncoupling, and thus, contribute to difficulties in orthodontic treatment and the risk of side effects of antiresorptive drugs.

Gene Expression of the RANK/RANKL/OPG System on a Three-Dimensional Culture of Human Periodontal Fibroblasts Under Continuous Compression

Gene Expression of the RANK/RANKL/OPG System on a Three-Dimensional Culture of Human Periodontal Fibroblasts Under Continuous Compression

A Potential Role of Semaphorin 3A during Orthodontic Tooth Movement.

Background: Induced tooth movement during orthodontic therapy requires mechano-induced bone remodeling. Besides various cytokines and growth-factors, neuronal guidance molecules gained attention for their roles in bone homeostasis and thus, potential roles during tooth movement. Several neuronal guidance molecules have been implicated in the regulation of bone remodeling. Amongst them, Semaphorin 3A is particular interesting as it concurrently induces osteoblast differentiation and disturbs osteoclast differentiation. Methods: Mechano-regulation of Sema3A and its receptors PlexinA1 and Neuropilin (RT-qPCR, WB) was evaluated by applying compressive and tension forces to primary human periodontal fibroblasts (hPDLF) and alveolar bone osteoblasts (hOB). The association of the transcription factor Osterix (SP7) and SEMA3A was studied by RT-qPCR. Mechanisms involved in SEMA3A-mediated osteoblast differentiation were assessed by Rac1GTPase pull-downs, β-catenin expression analyses (RT-qPCR) and nuclear translocation assays (IF). Osteogenic markers were analyzed by RT-qPCR. Results: SEMA3A, PLXNA1 and NRP1 were differentially regulated by tension or compressive forces in hPDLF. Osterix (SP7) displayed the same pattern of regulation. Recombinant Sema3A induced the activation of Rac1GTPase, the nuclear translocation of β-catenin and the expression of osteogenic marker genes. Conclusion: Sema3A, its receptors and Osterix are regulated by mechanical forces in hPDLF. SEMA3A upregulation was associated with Osterix (SP7) modulation. Sema3A-enhanced osteogenic marker gene expression in hOB might be dependent on a pathway involving Rac1GTPase and β-catenin. Thus, Semaphorin 3A might contribute to bone remodeling during induced tooth movement.

Targeting TSP-1 decreased periodontitis by attenuating extracellular matrix degradation and alveolar bone destruction

An important factor in periodontitis pathogenesis relates to a network of interactions of various cytokines. Thrombospondin-1 (TSP-1) is upregulated in several inflammatory diseases. We previously found that Porphyromonas gingivalis lipopolysaccharide (P. gingivalis LPS)-induced TSP-1 production, and that TSP-1 simultaneously and effectively elevated inflammatory cytokines in THP-1 macrophages. This suggests that TSP-1 plays an important role in the pathology of periodontitis. However, the function of TSP-1 on oral cells is largely unknown. This study aimed to elucidate the underlying molecular mechanisms of TSP-1 in human periodontal fibroblasts (hPDLFs). We demonstrated that TSP-1 is highly expressed in the gingival crevicular fluid of patients with chronic periodontitis and in the inflammatory gingival tissues of rats. TSP-1 overexpression or treatment with recombinant human TSP-1(rTSP-1) promoted the expression of MMP-2, MMP-9 and RANKL/OPG in hPDLFs, while anti-TSP-1 inhibited cytokines production from P. gingivalis LPS-treated hPDLFs. Additional experiments showed that SB203580 (a special p38MAPK inhibitor) inhibited MMP-2, MMP-9 and RANKL/OPG expression induced by rTSP-1. Thus, TSP-1 effectively promoted P. gingivalis LPS-induced periodontal tissue (extracellular matrix (ECM) and alveolar bone) destruction by the p38MAPK signalling pathway, indicating that it may be a potential therapeutic target against periodontitis.

Regulation of Anti-Apoptotic SOD2 and BIRC3 in Periodontal Cells and Tissues.

The aim of the study was to clarify whether orthodontic forces and periodontitis interact with respect to the anti-apoptotic molecules superoxide dismutase 2 (SOD2) and baculoviral IAP repeat-containing protein 3 (BIRC3). SOD2, BIRC3, and the apoptotic markers caspases 3 (CASP3) and 9 (CASP9) were analyzed in gingiva from periodontally healthy and periodontitis subjects by real-time PCR and immunohistochemistry. SOD2 and BIRC3 were also studied in gingiva from rats with experimental periodontitis and/or orthodontic tooth movement. Additionally, SOD2 and BIRC3 levels were examined in human periodontal fibroblasts incubated with Fusobacterium nucleatum and/or subjected to mechanical forces. Gingiva from periodontitis patients showed significantly higher SOD2, BIRC3, CASP3, and CASP9 levels than periodontally healthy gingiva. SOD2 and BIRC3 expressions were also significantly increased in the gingiva from rats with experimental periodontitis, but the upregulation of both molecules was significantly diminished in the concomitant presence of orthodontic tooth movement. In vitro, SOD2 and BIRC3 levels were significantly increased by F. nucleatum, but this stimulatory effect was also significantly inhibited by mechanical forces. Our study suggests that SOD2 and BIRC3 are produced in periodontal infection as a protective mechanism against exaggerated apoptosis. In the concomitant presence of orthodontic forces, this protective anti-apoptotic mechanism may get lost.

Cytotoxicity and Oxidative Stress Induction by Root Canal Sealers in Human Periodontal Ligament Fibroblasts: An in vitro Study.

The aim of the study was to investigate the in vitro cytotoxicity, the profile of cell death, and the level of oxidative stress in human periodontal ligament fibroblasts (HPdLFs) after exposure to selected root canal sealers. Freshly mixed or set Endomethasone N (EN), RealSeal (RSEAL), Roeko Seal Automix (RSA), and Sealapex (SP) were incubated with HPdLFs. Fluorescein isothiocyanate (FITC)-annexin V (AnV) and propidium iodide (PI) staining followed by flow cytometry was used to identify the effects of the materials on cell viability and the profile of cell death. 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) with fluorescence-activated cell sorting was used to determine reactive oxygen species (ROS) formation in HPdLFs. Statistical analyses were performed using one-way ANOVA followed by post hoc tests, and significance was determined at P<0.05. All materials reduced the viability of the cultured cells compared with the controls (P<0.05). Fresh SP and EN, and set RSA generated an increase of necrotic cells (P<0.05), whilst fresh RSEAL and RSA induced an elevation of apoptotic cells (P<0.001). Set RSEAL caused a rise in both apoptotic and necrotic cells compared with the controls (P<0.05). Fresh EN, RSEAL, and SP resulted in increased intracellular ROS generation compared with the negative control (P<0.001), whilst fresh RSA and all set materials were ineffective. This in vitro study showed us the materials tested were characterized by differentiated cytotoxic effects on HPdLFs. The fresh and set forms of sealers were capable of eliciting toxic action, inducing apoptosis and/or necrosis in HPdLFs. The toxic effects of fresh EN, RSEAL, and SP might have been due to the induction of oxidative stress in human periodontal fibroblasts. The cytotoxicity of RSA seemed to be related to the involvement of other mechanisms.

Comparative Evaluation of Cytotoxic and Genotoxic Effects of Three Resin-Based Sealers by 3,(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide Assay and Comet Assay - An In Vitro Study.

Background and Aim:The complete sealing of the pulpal space contributes to the better healing potential after an root canal treatment, and root canal sealers are an integral part of this treatment which comes in contact with the periodontal tissue. Biocompatibility of an endodontic sealer plays an important role in the root canal treatment procedure. Hence, the aim of the study was to compare and evaluate the cytotoxicity and genotoxicity effect of three resin-based sealers on human periodontal fibroblast cells.Settings and Design:This in vitro study was conducted in Dr. Prabhakar Kore's Basic Science and Research Center and K. L. E V. K. Institute of Dental Sciences, Belagavi.Materials and Methods:Human periodontal fibroblasts were incubated with 15 specimens of Group 1 – AH Plus Group 2 – MTA Fillapex, and Group 3 - GuttaFlow 2, respectively. Cytotoxicity was assessed by 3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and genotoxicity was assessed by Comet assay at time intervals at 24 h and 48 h.Statistical Analysis:Data were analyzed by the Kruskal–Wallis and Mann–Whitney U-test.Results:AH Plus and GuttaFlow 2 did not show any cytotoxicity or genotoxicity. MTA Fillapex was slightly cytotoxic throughout the time interval, and it also showed low genotoxicity throughout the time periods for which it was tested.Conclusion:AH Plus and GuttaFlow 2 did not show any cytotoxic and genotoxic effect; however, MTA Fillapex showed cytotoxic and genotoxic effect throughout the time interval.

CXCL5, CXCL8, and CXCL10 regulation by bacteria and mechanical forces in periodontium

ObjectiveThe aim of the present study was to evaluate the expressions of CXCL5, CXCL8, and CXCL10 in periodontal cells and tissues in response to microbial signals and/or biomechanical forces. MethodsHuman gingival biopsies from inflamed and healthy sites were used to examine the chemokine expressions and protein levels by real-time PCR and immunohistochemistry. The chemokines were also investigated in gingival biopsies from rats submitted to experimental periodontitis and/or tooth movement. Furthermore, chemokine levels were determined in human periodontal fibroblasts stimulated by the periodontopathogen Fusobacterium nucleatum and/or constant tensile forces (CTS) by real-time PCR and ELISA. Additionally, gene expressions were evaluated in periodontal fibroblasts exposed to F. nucleatum and/or CTS in the presence and absence of a MAPK inhibitor by real-time PCR. ResultsIncreased CXCL5, CXCL8, and CXCL10 levels were observed in human and rat gingiva from sites of inflammation as compared with periodontal health. The rat experimental periodontitis caused a significant (p<0.05) increase in alveolar bone resorption, which was further enhanced when combined with tooth movement. In vitro, F. nucleatum caused a significant upregulation of CXCL5, CXCL8, and CXCL10 at 1 day. Once the cells were exposed simultaneously to F. nucleatum and CTS, the chemokines regulation was significantly enhanced. The transcriptional findings were also observed at protein level. Pre-incubation with the MEK1/2 inhibitor significantly (p<0.05) inhibited the stimulatory actions of F. nucleatum either alone or in combination with CTS on the expression levels of CXCL5, CXCL8, and CXCL10 at 1d. ConclusionsOur data provide original evidence that biomechanical strain further increases the stimulatory actions of periodontal bacteria on the expressions of these chemokines. Therefore, biomechanical loading in combination with periodontal infection may lead to stronger recruitment of immunoinflammatory cells to the periodontium, which might result in an aggravation of periodontal inflammation and destruction.

Compressive force strengthened the pro-inflammatory effect of zoledronic acid on il-1ß stimulated human periodontal fibroblasts

The number of patients in dentistry taking bisphosphonates (BP) increases every year. There are only little data about the influence of biomechanical stress due to orthodontic treatment and periodontal inflammation in BP patients. This study focused on the effects of the induced inflammation by IL-1ß in compressed human periodontal ligament fibroblasts (HPdLF) exposed to the nitrogen-containing BP zoledronate in vitro. HPdLF were incubated with 5 μmol/l zoledronate and 10 ng/ml IL-1ß for 48 h. In the last 3 h, cells were exposed to a compressive, centrifugal force of 34.9 g/cm2. Cell viability was analyzed directly after the compressive force by MTT assay. Gene expression of COX-2 and IL-6 was investigated using quantitative qRT-PCR. PGE-2 and IL-6 protein secretion were measured via ELISA. The cell viability of HPdLF was not affected. Without inflammatory pre-stimulation, COX-2 expression was increased by compression and zoledronate. IL-6 expression was increased under compression. On secretion level, the combination of compression and zoledronate induced a slightly increase of IL-6 secretion. In contrast, inflammatory pre-stimulation strengthened the compressive upregulation of COX-2, as well as induced a higher PGE-2 secretion. Further addition of zoledronate to pre-stimulated cells additionally strengthened the compression-induced upregulation of COX-2 and IL-6 expression as well as protein secretion compared to all other groups. Biomechanical stress might trigger a pro-inflammatory potential of BP further enhanced in the presence of an inflammatory pre-stimulation. To prevent excessive host inflammatory responses, occlusal overloading and mechanical stress due to orthodontic treatment should be avoided in BP patients with untreated periodontitis.

Evaluation of Human Periodontal Ligament and Osteosarcoma Cell Attachment and Viability on Particulate Bone and Dentin Allografts

Purpose: Various bone grafting substitutes have been used in the periodontics for bone regeneration which include autografts, allografts, xenografts and alloplasts. Autogenous particulate dentin has been used successfully as a bone grafting substitute. The aim of present study was to evaluate the effect of demineralized and mineralized freeze-dried bone allograft and particulate dentin on osteoblasts-like cells and human periodontal fibroblasts. Materials and methods: Demineralized freeze-dried bone allograft (DFDBA) and freeze-dried bone allograft (FDBA) and ground dentin was used in the study. Particulate dentin was divided into four groups according to the size of the particles and demineralization - small dentin (particle size less than 200 µm), small dentin demineralized, large dentin (particle size 250-1200 µm), large dentin demineralized. Effect of all the specimens was checked on osteoblast-like cells (MG63) and human periodontal ligament cell lines. Percentage of surviving cells was measured using colorimetric MTT assay spectrophotometrically on 7th and 14th day of the cell culture. Scanning electron microscopy (SEM) was used to check the cellular attachment. Results: Demineralized dentin matrix has shown significantly enhanced viable cell percentage for both the cell lines. DFDBA and demineralized dentin has reported comparable percentage of surviving cells. Dentin seems to be more compatible with osteoblastslike cells than fibroblast. FDBA has shown the least favorable results. Cellular attachment for both the cell lines can be appreciated on SEM images. Conclusion: Demineralized particulate dentin has reported considerable percentage of cell viability making it a reasonable option for bone grafting substitute.

Is nicotine damaging to oral tissues?

Data sources The review included 42 pre-clinical in-vitro studies, published between 1995 and 2017. Study selection The study selected in-vitro studies which had assessed the effect of nicotine on human gingival and periodontal fibroblasts and epithelial cells. Typically, diluted pure nicotine was added to a cell culture medium in a variety of doses for a variety of time periods and the cells were then compared against a no-nicotine control. Outcomes assessed were: Cell viability, cell attachment or adhesion, cell proliferation or inflammatory mediator production. Studies were restricted to English language and full-text only.Data extraction and synthesis Two members of the review team screened abstracts and reviewed the full-texts independently. Disagreements regarding inclusion were resolved by discussion and consultation with the third author. Data were also extracted independently using a specifically designed data extraction form which included a quality assessment specifically designed for in-vitro studies. A narrative synthesis of the results was carried out.Results The included studies were heterogeneous in their designs, with a wide variety of cell types, concentrations of nicotine (1 nM to 100 mM), exposure times (30 minutes to four weeks), and assays used. All studies were assessed at being at high risk of bias due to lack of randomisation, allocation concealment, and blinding. No effect on cell viability was observed when the nicotine concentrations used were within the ranges observed in-vivo in smokers, nicotine replacement therapy users (NRT) and e-cigarette users. Cell viability was adversely affected only when concentrations of nicotine reached those observed in the saliva of smokeless tobacco users (>5 mM). However, periodontal ligament cells are not usually exposed to saliva in-vivo. Effects on cell attachment, cell proliferation and production of inflammatory mediators were reported at a wide range of concentrations, but the effects were contradictory. The authors make several recommendations for future research in this area, to improve the quality of the primary studies. Conclusions At the concentrations found in smokers and users of NRT including e-cigarettes, nicotine is unlikely to be toxic to human gingival and periodontal ligament cells in in-vitro. Higher concentrations of nicotine, of the levels observed in the saliva of smokeless tobacco users, have been shown to be cytotoxic in vitro.

Is nicotine damaging to oral tissues?

Data sources The review included 42 pre-clinical in-vitro studies, published between 1995 and 2017. Study selection The study selected in-vitro studies which had assessed the effect of nicotine on human gingival and periodontal fibroblasts and epithelial cells. Typically, diluted pure nicotine was added to a cell culture medium in a variety of doses for a variety of time periods and the cells were then compared against a no-nicotine control. Outcomes assessed were: Cell viability, cell attachment or adhesion, cell proliferation or inflammatory mediator production. Studies were restricted to English language and full-text only.Data extraction and synthesis Two members of the review team screened abstracts and reviewed the full-texts independently. Disagreements regarding inclusion were resolved by discussion and consultation with the third author. Data were also extracted independently using a specifically designed data extraction form which included a quality assessment specifically designed for in-vitro studies. A narrative synthesis of the results was carried out.Results The included studies were heterogeneous in their designs, with a wide variety of cell types, concentrations of nicotine (1 nM to 100 mM), exposure times (30 minutes to four weeks), and assays used. All studies were assessed at being at high risk of bias due to lack of randomisation, allocation concealment, and blinding. No effect on cell viability was observed when the nicotine concentrations used were within the ranges observed in-vivo in smokers, nicotine replacement therapy users (NRT) and e-cigarette users. Cell viability was adversely affected only when concentrations of nicotine reached those observed in the saliva of smokeless tobacco users (>5 mM). However, periodontal ligament cells are not usually exposed to saliva in-vivo. Effects on cell attachment, cell proliferation and production of inflammatory mediators were reported at a wide range of concentrations, but the effects were contradictory. The authors make several recommendations for future research in this area, to improve the quality of the primary studies. Conclusions At the concentrations found in smokers and users of NRT including e-cigarettes, nicotine is unlikely to be toxic to human gingival and periodontal ligament cells in in-vitro. Higher concentrations of nicotine, of the levels observed in the saliva of smokeless tobacco users, have been shown to be cytotoxic in vitro.

Activation of cannabinoid receptors promote periodontal cell adhesion and migration.

Medical and recreational cannabis use is increasing significantly, but its impacts on oral health remain unclear. The aim of this study is to investigate the effects of tetrahydrocannabinol (THC), the major active component in cannabis, on periodontal fibroblast cell adhesion and migration to explore its role in periodontal regeneration and wound healing. The different distribution of cannabinoid receptors 1 (CB1) and 2 (CB2) was characterized in the mouse periodontium. Human periodontal fibroblast cell (HPLF) adhesion and migration was analysed by in vitro wound healing assay with and without THC. The focal adhesion kinase (FAK) signalling pathway was investigated to uncover the underlying cellular mechanism. The receptor dependency of cannabinoid effects was examined by using selective antagonists to block THC. Both CB1 and CB2 were expressed in periodontal tissues but with different expression patterns. Tetrahydrocannabinol promoted periodontal cell wound healing by inducing HPLF cell adhesion and migration. This was mediated by focal adhesion kinase (FAK) activation and its modulation of MAPK activities. The effect of cannabinoids on periodontal fibroblast cell adhesion and migration was mainly dependent on the CB2. These results suggested that cannabinoids may contribute to developing new therapeutics for periodontal regeneration and wound healing.