Impact of periodontitis on oral health-related quality of life

ObjectivesTo investigate the impact of chronic periodontitis on oral health-related quality of life (OHRQoL) using the full version of the Oral Health Impact Profile (OHIP-49) and the Oral Health Quality of Life-UK (OHQoL-UK) questionnaires.Methods89 patients with chronic periodontitis and 89 age- and gender-matched patients without chronic periodontitis were recruited. OHIP-49 and OHQoL-UK were self-completed by participants and mean scores were calculated for each item, domain and the overall summary score (additive method) for each instrument in each group.ResultsThe mean age of participants was 47 ± 9 years, and the periodontitis patients had, on average, 33 ± 23 sites demonstrating probing depths ≥5 mm. OHRQoL was significantly poorer in the periodontitis patients compared to the periodontally healthy patients, when assessed by either instrument. When considering OHIP-49, fourteen of the forty-nine items indicated significantly poorer OHRQoL in the periodontitis group, and the overall OHIP-49 summary score was 48.6 ± 32.0 for periodontitis patients compared to 36.8 ± 29.8 in periodontally healthy patients (p < 0.01). When considering OHQoL-UK, fifteen of the sixteen items indicated significantly poorer OHRQoL in the periodontitis group, and the overall OHQoL-UK summary score was 47.1 ± 9.7 for periodontitis patients compared to 53.1 ± 11.3 in periodontally healthy patients (p < 0.01). Overall, those items with the greatest differences between periodontitis patients and the healthy group related to psychological concerns, halitosis, pain and aesthetics.ConclusionSubjects with periodontitis report substantial functional, physical, psychological, and social OHRQoL impacts.Clinical significanceThis study has identified that patients with chronic periodontitis report significantly poorer oral health-related quality of life (OHRQoL) than age- and gender-matched periodontally healthy patients, with significant functional, social and psychological impacts. Clinicians should be aware of the impacts that periodontitis may have on OHRQoL, including psychological concerns, halitosis, pain and aesthetics.     

Quantification of tryptase-TIM-3 double-positive mast cells in human chronic periodontitis

ObjectivesMast cells (MCs) are implicated in the pathogenesis of allergic reactions and inflammatory conditions through the release of inflammatory mediators. So far limited attention has been given to the role of MCs in periodontitis. T cell immunoglobulin mucin domain (TIM)-3 is an immunomodulatory molecule and influences MC function. However, whether TIM-3 is expressed on MCs in the process of human periodontal disease has not been reported. Therefore, we identified MCs by toluidine blue staining and examined the expression of TIM-3 on tryptase-positive MCs in different severities of human chronic periodontitis using double-immunofluorescence staining in this study.Material and methodsA total of 83 human periodontal specimens were involved in this study, including healthy control tissues (n = 25), chronic moderate periodontitis (n = 28), and chronic severe periodontitis (n = 30). The gingival specimens were fixed in 10% buffered formalin, stained with haematoxylin and eosin for histopathology, with toluidine blue for MCs, and with double-immunofluorescence for identification of tryptase-TIM-3 double-positive MCs in gingival tissues.ResultsCompared with healthy controls, the score of gingival tissue inflammation was significantly increased in the chronic moderate periodontitis (P = 0.013) and chronic severe periodontitis (P < 0.0001), and the densities (cells/mm²) of tryptase-TIM-3 double-positive MCs were significantly increased in both the chronic moderate (P = 0.011) and severe periodontitis groups (P < 0.0001). However, compared with the chronic moderate periodontitis group, both the score of gingival tissue inflammation (P = 0.012) and the density of tryptase-TIM-3 double-positive MCs (P = 0.011) in gingival tissue were significantly increased in the severe periodontitis groups.ConclusionSignificantly increased number of tryptase-TIM-3 double-positive MCs had the similar tendency as the severity of periodontitis inflammation in human chronic periodontitis. Our data suggest that TIM-3 may have a role on MCs in human chronic periodontitis.     

Expression of human beta defensins (HBDs) 1, 2 and 3 in gingival crevicular fluid of patients affected by localized aggressive periodontitis

AimTo study the effect of nonsurgical periodontal therapy on the expression frequencies of human beta-defensin (HBD)-1, -2, and -3 in the gingival crevicular fluid (GCF) of patients affected by localized aggressive periodontitis.Materials and methodsTwenty patients affected by localized aggressive periodontitis (age range, 20–35 years) and 20 healthy subjects (age range, 21–37 years) were examined with clinical periodontal parameters and radiographic examination with the long-cone parallel technique. All periodontitis patients underwent nonsurgical periodontal therapy combined with doxycycline treatment and a maintenance program (including brushing with regular toothpaste). GCF samples were collected from patients and healthy control subjects at baseline as well as 3 months after periodontal therapy for the patient group.ResultsIn the patient group, the expression frequencies of HBD-1, -2, and -3 mRNA at baseline were 30%, 85%, and 35%, respectively, which changed after periodontal therapy to 80%, 45%, and 85%, respectively (all P < 0.001). In the healthy control subjects, the expression frequencies were 95%, 40%, and 95% for HBD-1, -2, and -3, respectively, which were different from those of diseased patients at baseline (all P < 0.001).ConclusionsThe appropriate expression of HBD peptides in health and disease may contribute to the maintenance of periodontal homeostasis, possibly through its antimicrobial effects and the promotion of adaptive immune responses.     

The effect of initial periodontal treatment on plasma,gingival crevicular fluid and salivary levels of 8-hydroxy-deoxyguanosine in obesity

ObjectiveRecent studies have shown adverse effects on the periodontium from the increased production of reactive oxygen species (ROS) in obesity. The purpose of this study was to investigate the effects of obesity on 8-hydroxy-deoxyguanosine (8-OHdG) levels in the bodily fluids of patients with and without periodontal disease and to evaluate changes after initial periodontal treatment.DesignForty-five obese individuals and 45 normal-weight individuals were included in this study. Obese and normal-weight groups were classified into three sub-groups: chronic periodontitis (CP), gingivitis (G) and periodontally healthy controls (CTRL). Gingival crevicular fluid (GCF), plasma, saliva samples and clinical measurements were obtained at baseline and a month after initial periodontal treatment. Levels of 8-OHdG were analysed by ELISA.ResultsWhile plasma 8-OHdG levels were significantly higher at baseline in the obese patients with periodontal disease than in the normal-weight individuals (P < 0.05), no significant differences in GCF and saliva 8-OHdG levels were found (P ˃ 0.05). GCF and salivary 8-OHdG levels in obese patients with G and CP were significantly higher than in CTRL groups at baseline (P < 0.05). After treatment, 8-OHdG levels were decreased in all groups with periodontal disease (P < 0.01). Statistically significant positive correlations were observed between GCF 8-OHdG levels and GI in all the groups (P < 0.001).ConclusionsThe significant increase of plasma 8-OHdG levels in obese patients did not correlate with saliva and GCF 8-OHdG levels when compared to normal-weight individuals. Periodontal treatment had a positive effect on the periodontal parameters and 8-OHdG levels of both obese and normal-weight individuals.     

Frequency of MCP-1 (rs1024611) and CCR2 (rs1799864) gene polymorphisms and its effect on gene expression level in patients with AgP

ObjectiveTo identify the genetic risk markers of aggressive periodontitis (AgP), researchers focus on genetic components that regulate the immune response. Therefore the purpose of this study was to investigate genetic impact of monocyte chemoattractant protein (MCP)-1–2518 A/G and CC chemokine receptor 2 (CCR2) −190 G/A gene polymorphisms on AgP susceptibility and the effect of this polymorphism on MCP-1 gene expression in patients with AgP.Material and methodsA total of 215 subjects, 108 AgP and 107 periodontally healthy (H) were recruited in this cross-sectional study (NCT02817568). Gene polymorphisms of MCP-1–2518 A/G and CCR2–190 G/A were analyzed by a standard polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. MCP-1 messenger (m) RNA expression was measured using quantitative real-time (RT)-PCR in peripheral blood leukocytes from 26 AgP and 16 H controls. Threshold cycles (C_t) values were obtained from the RT-PCR analysis based on SYBR Green detection and data was normalized via ΔC_t.ResultsThere were no differences between AgP and H groups with regard to MCP-1 and CCR2 genotype distribution and allele frequencies (p > 0.05). In contrast, the MCP-1 mRNA expression levels were higher in homozygous “AA” control subjects than having G⁺ genotype and AA homozygous AgP patients.ConclusionsIt can be concluded that MCP-1 and CCR2 polymorphisms are not associated with AgP in Turkish population. Although in AgP patients, there was AA genotype with MCP-1 mRNA expression it can be speculated that gene expression levels in peripheral blood may not reflect the cytokine/chemokine levels of local tissues.     

Elevation of white blood cells and platelet counts in patients having chronic periodontitis

Background and aimMany risk factors that might contribute to the pathogenesis of atherosclerosis have been proposed, including chronic inflammation and infection. Furthermore, systemic inflammatory responses to periodontal bacteria have been suggested as a pathogenetic link between periodontal disease and atherosclerosis. The purpose of this study was to estimate the white blood cell (WBC) and platelet counts in chronic periodontitis patients.Materials and methodsFifty patients with chronic periodontitis and 50 patients with healthy periodontium were included in this study. Oral hygiene status, pocket probing depth (PPD) and clinical attachment level (CAL) were measured. During clinical evaluation, venous blood samples were taken to analyze the WBC and platelet counts. Statistical analysis was utilized to compare differences across groups.ResultsPeriodontitis patients demonstrated a significantly higher WBC count (7.22 ± 1.42 × 10⁹ cells/L) than that of control patients (5.64 ± 1.56 × 10⁹ cells/L; P < 0.001). The platelet count of patients with chronic periodontitis (290.73 ± 56.56 × 10⁹ cells/L) was also significantly higher compared to the healthy group (223.37 ± 50.27 × 10⁹ cells/L; P < 0.001).ConclusionLevels of WBCs and platelets are elevated in periodontitis patients compared to healthy controls.     

Impact of glycemic control on oral health status in type 2 diabetes individuals and its association with salivary and plasma levels of chromogranin A

ObjectiveTo evaluate the effect of glycemic control status in type 2 diabetes mellitus (T2DM) individuals on clinical oral health indicators and to compare the concentrations of plasma and salivary chromogranin A (CHGA) among nondiabetic subjects and T2DM patients, exploring their associations.DesignIn this cross-sectional study, 32 patients with controlled T2DM, 31 with poorly controlled T2DM and 37 nondiabetic subjects underwent a clinical and periodontal examination. CHGA concentrations were determined in saliva and plasma with ELISA.ResultsPoorly controlled T2DM group exhibited significantly higher mean buffering capacity, plaque index and bleeding on probing than other groups (P < 0.05). No difference was found to DMFT (decayed, missed and filled teeth) index between groups. Sites with clinical attachment loss (CAL) of 4 and 5–6 mm were significantly higher in both diabetic groups compared to control group (P < 0.05). Poorly controlled T2DM group had significantly higher sites with CAL ≥ 7 mm than other groups (P = 0.001). Significantly higher plasma and salivary CHGA levels were found in T2DM groups (P < 0.05). In both diabetic groups, probing depths 5–6 mm and CAL 5–6 mm were associated with higher salivary CHGA concentration (P < 0.05).ConclusionsThe findings revealed that T2DM patients were more prone to periodontal tissue damage than to caries risk. The results also provide some evidence that the degree of attachment loss deteriorates significantly with poor glycemic control in T2DM (CAL ≥ 7 mm). Moreover, the results suggest that high concentrations of salivary CHGA are associated with worse periodontal parameters and T2DM, and this could be related to the pathogenesis of both diseases.     

The expression of antioxidant enzymes in the gingivae of type 2 diabetics with chronic periodontitis

ObjectivesThere is controversial evidence regarding the levels of antioxidant molecules in type 2 diabetes periodontitis patients. Thus, the aim of the present study was to evaluate the gene expression of antioxidant enzymes in the gingival tissue of poorly and well-controlled type 2 diabetic subjects with chronic periodontitis (CP).DesignGingival biopsies were harvested from systemically and periodontally healthy subjects (n = 12), systemically healthy subjects with CP (n = 15), well-controlled (n = 8) and poorly controlled (n = 14) diabetic subjects with CP. The messenger RNA (mRNA) levels of peroxiredoxin (PRDX) 1 and 2, catalase (CAT), glutathione peroxidase (GPX1) and superoxide dismutase (SOD) 1 and 2 were measured by quantitative polymerase chain reaction (qPCR).ResultsThe results showed that PRDX1 and GPX1 were up-regulated by periodontitis (p < 0.05), independently of the glycaemic status, whilst PRDX2 and SOD2 genes were slightly influenced by periodontitis, but significantly induced when periodontitis was associated with DM, especially under a poor glycaemic control (p < 0.05). Moreover, CAT and SOD1 expressions were not significantly influenced by any of these inflammatory disorders (p > 0.05).ConclusionIn conclusion, both PRDX1 and GPX1 were overexpressed in CP whilst PRDX2 and SOD2 were up-regulated especially in the poorly controlled diabetic group with CP.     

Diabetes increases interleukin-17 levels in periapical,hepatic, and renal tissues in rats

ObjectivesThis study aimed to evaluate the association between endodontic infection and diabetes on interleukin-17 levels in periapical, hepatic, and renal tissues of rats.DesignForty male rats were divided into groups: normoglycemic rats (N), normoglycemic rats with apical periodontitis (N-AP), rats with experimental diabetes (ED), and rats with experimental diabetes and apical periodontitis (ED-AP). Diabetes was induced by intravenous streptozotocin injection, and blood sugar levels were monitored to confirm disease development. Apical periodontitis (AP) was induced by pulp exposure to the oral environment during 30 days. After 30 days, hepatic and renal tissues were obtained, and IL-17 levels were quantified by ELISA. The right hemi-jaw was used to quantify IL-17 levels by immunohistochemistry. The values obtained in parametric tests were tabulated and analyzed statistically by analysis of variance (ANOVA) and Tukey tests, and the values obtained for scores were statistically analyzed by using the Kruskal-Wallis and Dun tests. The level of significance was set at 5%.ResultsED and ED-AP groups expressed significantly higher IL-17 levels in both hepatic and renal tissues (p < 0.05), compared to N and N-AP groups. Apical periodontitis (AP) in ED-AP group was significantly more severe than that in N-AP group (p < 0.05). Furthermore, there was a significantly larger increase in the IL-17 levels in ED-AP group compared to N group (p < 0.05).ConclusionOur results indicate that diabetes increases IL-17 levels in hepatic and renal tissues and also enhances IL-17 production in apical periodontitis area of rats.     

Study of the participation of MMP-7, EMMPRIN and cyclophilin A in the pathogenesis of periodontal disease

Background and objectivePeriodontal disease is an infectious disease resulting from the immunoinflammatory response of the host to microorganisms present in the dental biofilm which causes tissue destruction. The objective of this study was to evaluate the immunohistochemical expression of matrix metalloproteinase 7 (MMP-7), extracellular matrix metalloproteinase inducer (EMMPRIN) and cyclophilin A (CypA) in periodontal disease.DesignGingival tissue samples were divided as follows: clinically healthy gingiva (n = 32), biofilm-induced gingivitis (n = 28), and chronic periodontitis (n = 30). Histological sections of 3 μm were submitted to immunoperoxidase method and undergone quantitative analysis. The results were analyzed statistically by the Mann-Whitney and Spearman correlation tests, with the level of significance set at 0.05 (α = 0.05).ResultsImmunopositivity for MMP-7, EMMPRIN and CypA differed significantly between the three groups, with higher percentages of staining in chronic periodontitis specimens, followed by chronic gingivitis and healthy gingiva specimens (p < 0.05). Immunoexpression of CypA and MMP-7 was higher in the intense inflammatory infiltrate observed mainly in cases of periodontitis (p < 0.05). CypA expression was positively correlated with MMP-7 (r = 0.831; p < 0.001) and EMMPRIN (r = 0.289; p = 0.006). In addition, there was a significant positive correlation between probing depth and expression of MMP-7 (r = 0.726; p < 0.001), EMMPRIN (r = 0.345; p = 0.001), and CypA (r = 0.803; p < 0.001).ConclusionThese results suggest that MMP-7, EMMPRIN and CypA are associated with the pathogenesis and progression of periodontal disease.     

Ethanol consumption enhances periodontal inflammatory markers in rats

ObjectiveThe aim of this study was to assess the short term effect of ethanol administration on periodontal disease in rats.DesignRats received either ethanol 2 g/kg or water by gastric gavage twice a day. On the fifth day ligatures were tied around the molars of half of the rats to induce periodontitis. After 7 days gingival tissue was removed and assayed for inflammatory markers. Finally, hemi-mandibles were extracted to evaluate bone loss by histomorphometrical techniques.ResultsThe experimental periodontitis increased significantly the mRNA expression (p < 0.001) and activity (p < 0.001) of inducible nitric oxide synthase (iNOS) in the gingival tissue, whilst short time ethanol administration increased iNOS activity (p < 0.05) and produced an additive effect on iNOS mRNA expression augmented by periodontitis (p < 0.01). The short time ethanol administration also potentiated the periodontitis stimulatory effect on the mRNA expression of interleukin (IL)-1β (p < 0.01 and p < 0.001, in semi-quantitative and real time PCR, respectively) and on the height of periodontal ligament (p < 0.05). However, the ligature-induced periodontitis, but not ethanol administration, increased the prostaglandin E₂ content (p < 0.05) and, diminished the alveolar bone volume (p < 0.05), as compared to sham rats.ConclusionThe present results suggest that ethanol consumption could represent a risk indicator for periodontal disease since augments the expression of inflammatory markers, in healthy rats, and increases them, at short term, during the illness. However, scale longitudinal investigation and more case–control studies are needed to confirm this statement.     

Frequency of periodontal pathogens in equivalent peri-implant and periodontal clinical statuses

ObjectivesThis study tested the hypotheses that there is: (1) higher bacterial frequency in peri-implantitis/periodontitis, followed by mucositis/gingivitis and peri-implant/periodontal health; (2) similar bacterial frequency between comparable peri-implant and periodontal clinical statuses.Design of studyThe presence of Porphyromonas gingivalis, Tannerella forsythia, Campylobacter rectus, Prevotella intermedia, Treponema denticola and Aggregatibacter actinomycetemcomitans was evaluated in peri-implant (n = 53) and periodontal (n = 53) health; mucositis (n = 50), gingivitis (n = 50), peri-implantitis (n = 50) and periodontitis (n = 50).ResultsThe pattern of peri-implant bacterial frequency was not as expected (peri-implantitis > mucositis > health). Except for P. intermedia (p > 0.05), bacterial frequency was higher in peri-implantitis than health (p < 0.05). The frequency of P.gingivalis and red complex species were higher in peri-implantitis than mucositis (p < 0.05). In periodontal samples, T. forsythia and T. denticola showed the expected pattern of frequency (periodontitis > gingivitis > health). The frequencies of C. rectus and T. forsythia were higher in healthy teeth/gingivitis than healthy implants/mucositis, respectively (p < 0.05). The frequency of P. gingivalis and A. actinomycetemcomitans were similar between periodontitis and peri-implantitis (p > 0.05) while all other species occurrences were higher in periodontitis than peri-implantitis (p < 0.05).ConclusionsBacterial frequency increased from peri-implant/periodontal health to peri-implantitis/periodontitis but not from mucositis/gingivitis to peri-implantitis/periodontitis. There was a trend towards higher bacterial frequency in teeth than implants.     

Association of CXCL12 gene promoter methylation with periodontitis in patients with diabetes mellitus type 2

ObjectivesCXCL12 is widely expressed, constitutive chemokine involved in tissue repair and regeneration, while the extent of its expression is important in various chronic inflammatory conditions. Involvement of DNA methylation in CXCL12 gene suppression (CXCL12) has been shown in malignancy and some autoimmune diseases. The aim of this study was to investigate whether the alterations in DNA methylation of CXCL12 are also involved in progression of periodontitis in combination with diabetes, as these chronic inflammatory conditions are strongly interrelated.DesignStudy included 72 subjects divided in three groups: healthy control (C, n = 21), periodontitis (P, n = 29) and diabetes/periodontitis group (D/P, n = 22). DNA extracted from epithelial cells obtained by sterile cotton swabs from buccal mucosa was subjected to methylation specific polymerase chain reaction (MSP) to obtain DNA methylation pattern of CXCL12 promoter.ResultsCXCL12 promoter was predominantly unmethylated in all groups. However, increase in the frequency of the methylated form and increase in percent of methylation of CXCL12 promoter in periodontitis and diabetes/periodontitis group compared to control group were found, although without statistical significance. However, statistically significant increase in Tm of MSP products in diabetes/periodontitis group was observed. Correlation analysis revealed statistically significant relationship between the extent of DNA methylation of the CXCL12 promoter and periodontal parameters, as well as between DNA methylation of CXCL12 and glycosylated hemoglobin.ConclusionPresented results suggest that chronic inflammation contributes to the change of CXCL12 DNA methylation in buccal cells and that DNA methylation profile of CXCL12 promoter plays important role in development and progression of periodontal disease.     

Effects of connective tissue growth factor on human periodontal ligament fibroblasts

ObjectiveThe aim of this study was to evaluate the effects of different concentrations of connective tissue growth factor (CTGF) on human periodontal ligament fibroblasts(HPLFs).DesignHPLFs were cultured and identified. Then, different concentrations of CTGF (1, 5, 10, 50, 100 ng/ml) were added to the HPLF culture. Next, CCK-8 assays, alkaline phosphatase (ALP) assays, hydroxyproline determination, alizarin red staining methods, Transwell chambers and real-time PCR methods were applied to observe the effects of CTGF on the proliferation, ALP activity, synthesis of collagen, formation of mineralized nodules and migration. We also studied expression of ALP, fiber link protein (FN), integrin-binding sialoprotein (IBSP), osteocalcin (OC), and integrin beta 1 (ITGB1) mRNA by HPLFs. Statistical significance was assumed if P < 0.05 or P < 0.01.ResultsThe addition of CTGF (1, 5, 10 ng/ml) remarkably promoted the proliferation and collagen synthesis of HPLFs compared with controls. CTGF (1, 5, 10, 50 ng/ml) improved ALP activity of HPLFs, and at all concentrations, CTGF (1, 5, 10, 50, 100 ng/ml) improved the expression of ALP, FN, IBSP and ITGB1 mRNA. In addition, CTGF (1, 5, 10, 50, 100 ng/ml) promoted the migration of HPLFs, which was dose-dependent, with maximal promotion in the 10 ng/ml group (P < 0.05 or P < 0.01).ConclusionsThus, in a certain range of concentrations, CTGF can promote the biological effects, including proliferation, migration and collagen synthesis of HPLFs, to promote the differentiation of HPLFs in the process of osteogenesis.     

Plasma polyunsaturated fatty acids and periodontal recovery in Taiwanese with periodontitis: A significant relationship

BackgroundPlasma levels of polyunsaturated fatty acids (PUFAs) are different before and after periodontal treatment. Asians and Westerners have significantly different baseline levels of plasma PUFAs. However, no Asian study has reported the effects of nonsurgical treatment on the correlation between periodontal condition and plasma levels of PUFAs. We analyzed whether recovery from periodontitis was correlated with the elevation of plasma fatty acids 3 months after the nonsurgical intervention and with no recommended supplements.DesignThirty-five Taiwanese patients with periodontitis were recruited. Probing pocket depths (PPDs) and clinical attachment levels (CALs) were measured at baseline and 3 months after the nonsurgical treatment. Plasma levels of fatty acids were determined using gas chromatography. Differences and correlations between plasma fatty acid composition and periodontitis severity at baseline and 3 months after treatment were determined.ResultsTwenty-six patients completed the study. At the baseline, PPDs were negatively correlated with plasma n-3 PUFAs (r = −0.52, p < 0.01), but at 3 months post intervention, periodontitis severity had declined and the weight percentages of n-3 PUFAs, DPA, and DHA were significantly (p = 0.019, 0.005, and 0.037, respectively) higher. The recovery percentages of CALs were positively and significantly correlated with plasma ΔPUFAs and the percentage of Δn-3 PUFAs in ΔPUFAs (r = 0.42 and 0.45, respectively; p < 0.05 for both).ConclusionsWe conclude that a higher weight percentage of n-3 PUFAs in total PUFAs was related to the recovery of CALs 3 months after the nonsurgical periodontal treatment. However, no such relationship was found for PPDs.     

Effects of prostaglandin E2 on clonogenicity,proliferation and expression of pluripotent markers in human periodontal ligament cells

Background and objectiveBased on our earlier work on the response of periodontal ligament (PDL) cells to mechanical stress by induction of cyclooxygenase expression and production of prostaglandin PGE₂ that could regulate mineralization of PDL cells, it was hypothesized that PGE₂ had potential effects on PDL stemness. In this study, we aimed to investigate clonogenicity, proliferation and expression of certain pluripotent markers, considered to be characteristics of PDL stemness, in response to treatment with exogenously-added PGE₂.Material and methodsHuman PDL cells were cultured and treated with various doses of PGE₂, and the aforementioned characteristics of PDL stemness were analyzed.ResultsThe clonogenicity and proliferation were significantly enhanced by PGE₂ at low concentrations (0.01, 0.1 and 1 ng/ml; P < 0.05), but only the proliferation was significantly diminished by PGE₂ at a high concentration (100 ng/ml; P < 0.05). Expression of NANOG and OCT4 mRNA and protein was increased by PGE₂ treatment at 0.1 and 1 ng/ml. Consistently, expression of stage-specific embryonic antigen 4, a putative stem cell marker, was significantly augmented by PGE₂ treatment at 1 ng/ml (P < 0.05).ConclusionOur findings suggest that although a high dose of PGE₂ (100 ng/ml) inhibits proliferation of PDL cells, PGE₂ at low doses appears to play a role in the maintenance of PDL stemness.     

Jaw-stretch reflex is weaker in patients after orthognathic surgery

ObjectivesThe jaw-stretch reflex (JSR) was studied in both patients and healthy participants in order to investigate the possible long-term impact of orthognathic surgery on the motor function of the masticatory system.DesignJSR was measured in patients before surgery (PC), 1 year after surgery (PS) and in healthy controls (HC) (N = 31 in each group). JSR was evoked by a standardized stretch device and recorded bilaterally from masseter and anterior temporalis muscles using surface electromyography (EMG).ResultsThe peak-to-peak amplitude (which was normalized to pre-stimulus EMG activity) of JSRs in PC and PS were significantly smaller than in HC (P < 0.001; P < 0.001). The onset latency in PS was significantly longer compared with HC (P < 0.05). The duration of JSR in PS was significantly longer than in HC and PC (P < 0.001; P < 0.05).ConclusionPatients with dentofacial deformities are characterized by reduced JSR amplitude. The delayed onset and elongated duration of JSR might be potential indicators of a long-term surgical impact on the motor function of the masticatory system.