Search

Periodontal pathogens are the main pathogenic factor of periodontitis. Periodontal pathogens have a large variety of virulence factors such as lipopolysaccharide, fimbriae and proteases, which enables the pathogens to infect periodontal tissues and stimulate the secretion of inflammatory cytokines, causing chronic systemic inflammation. Periodontal pathogens may invade multiple systems such as the circulatory system, immune system, respiratory system and digestive system to cause systematic diseases. Recent studies have shown that periodontal pathogens may have close relations with systemic diseases such as cardiovascular disease, diabetes, rheumatoid arthritis, and cancer. Among the periodontal pathogens, Porphyromonas gingivalis can be found in atherosclerotic plaques to impairing the function of the vascular endothelium; Porphyromonas gingivalis may also increase the level of inflammatory factors such as TNF-α to promote insulin resistance and diabetes. Many of the periodontal pathogens such as Porphyromonas gingivalis , Tannerella forsythia and Prevotella intermedia can be detected in the synovial fluid of rheumatoid arthritis patients, suggesting their involvement in the pathogenesis of rheumatoid arthritis. Fusobacterium nucleatum may cause alterations in the intestinal microbiome in mice and promote the occurrence of intestinal tumors. Herein we review the recent progresses in the relationship between periodontal pathogens and systemic diseases.

Purpose: To explore the effect of erythritol on the growth of Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans(Aa), Actinomices viscosus (Av), and to explore how Porphyromonas gingivalis affected by erythritol influence mRNA expression level of inflammatory in periodontal cells., Methods: Pg, Aa, Av were anaerobically cultured (80%N 2 , 10%CO 2 , 10%H 2 ) at 37℃ in 2, 4, 8, 16, 32, 64, 128 g/L erythritol- BHI mixture groups (experimental groups) and BHI groups (control group). The lowest erythritol concentration without turbidity or precipitation was the minimum inhibitory concentration. Pg was cultured in MIC, 1/2, 1/4, 1/8 MIC erythritol- BHI mixture groups (experimental groups) and BHI groups (control group). Each kind of bacteria in each concentration group was centrifugalled and cleaned before added into DMEM. The mixed suspension was co-cultured with the periodontal ligament cells in four generations for 24 hours, the supernatan was removed , then the total RNA in cracking cells was extracted and reversing transcription. At last, the relative expression of IL-1, IL-6, TNF-a was detected real-time fluorescent quantitative PCR. The data were analyzed with SPSS19.0 software package., Results: The minimum inhibitory by concentrations of erythritol on three bacteria were as followed: Pg: 64 g/L，Aa: 128 g/L，Av: 128 g/L. The ability of stimulating periodontal ligament cells to produce IL-1β, IL-6 and TNF-α was different when Pg was cultured under different concentrations of erythritol. There was no significant difference between 0 g/L of control group and 8 g/L of experimental group. As the concentration reached 16 g/L, the relative expression of IL-1β, IL-6, TNF-α was reduced, and the higher concentration was, the less inflammatory factors was. However, the inflammatory factors in all the experimental groups were always significantly higher than that in the blank control group (P<0.05)., Conclusions: Erythritol has an inhibitory effect on the growth of Pg, Aa and Av. In a certain range, higher concentration of erythritol delivers better inhibition effect. Erythritol can also reduce the periodontal pathogenicity of pathogenic bacteria in a way inhibiting the virulence of these bacteria, reducing the production of IL-1β, IL-6, and TNF-a in periodontal cells.

Objective: To investigate periodontal status of patients with pre-diabetes and evaluate the prevalence of periodontal pathogens in oral cavity. Methods: All the subjects were under regular care in urban area of Beijing, including 88 subjects with normal blood glucose (normal blood glucose group), 27 pre-diabetic patients (pre-diabetic group), 58 well-controlled diabetic patients (glucose well controlled group) and 72 poor-controlled diabetic patients (glucose poor controlled group). Whole unstimulated saliva samples were collected before periodontal examination. Periodontal parameters, including plaque index (PLI), probing depth (PD), bleeding index (BI), bleeding on probing (BOP) and clinical attachment loss (CAL), were examined at mesial-buccal and distal-lingual sites of each tooth. Number of missing teeth was recorded. DNA was extracted from the salivary deposition, Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Campylobacter rectus (Cr), and Prevotella nigrescens (Pn) were detected by using PCR method based on 16SrRNA. Periodontal status and prevalence and quantity of the pathogens under various blood glucose states were compared. Results: The PD scores of four groups had no statistical differences. The CAL [(2.29±1.35) mm] and the number of missing teeth[2.0 (7.0)] in pre-diabetic group were significantly lower than that in glucose poor controlled group [(3.07±1.45) mm, P= 0.04 and 5.0 (10.0), P= 0.04, respectively]. The number of missing teeth in pre-diabetic group [2.0 (7.0)] was significantly lower than that in glucose well controlled group [5.0 (9.0), P= 0.02]. The percent of bleeding on probing [BOP(+)%] in pre-diabetic group [(63.89±20.03)%] was significantly higher than that in normal blood glucose group [(54.51±22.29)%, P= 0.04] and glucose well controlled group [(53.12±21.77)%, P= 0.03]. The prevalence of Pg in pre-diabetic group (81.5%) was significantly higher than that in glucose poor controlled group (54.2%, P= 0.02). The prevalence of Tf in pre-diabetic group (96.3%) was significantly higher than that in glucose poor controlled group (76.4%, P= 0.01). Meanwhile the quantity of Pg [1.58 (4.75)] and Tf [5.46 (7.77)] in pre-diabetic group were significantly higher than that in glucose poor controlled group [0.60 (1.87), P= 0.01 and 1.63 (3.06), P< 0.01, respectively]. The quantity of Pn [0.85 (1.68)] in pre-diabetic group was significantly higher than that in normal blood glucose group [0 (1.02), P= 0.04]. Conclusions: Pre-diabetic patients showed severe periodontal infection and BOP(+)% than other three groups and had high risk-level of periodontitis.

Purpose: To detect the existence of Aa,Pg,Tf,Cr,Ec and Pn in the subgingival plaque, and determine their relationships among different types of periodontal diseases., Methods: Dental plaques from 120 subjects were sampled, including 40 volunteers with health periodontal status(Group A) , forty patients with dental plaque-induced gingival diseases(Group B) and 40 patients with moderate or severe chronic periodontitis (Group C) . These samples were detected based on bacterial composition using the terminal restriction fragment length polymorphism of 16S rRNA genes by multiple-polymerase chain reaction. The data was analysed with SPSS 13.0 software package for Chi-square test., Results: The detection rate of Pn, Cr and Pg had significant differences between group A and B. The detection rate of Ec, Cr, Pg, Aa and Tf had significant differences between group C and B. The detection rate of Ec, Pn, Cr, Pg, Aa and Tf had significant differences between group A and C., Conclusions: The rate of Ec, Pn, Cr, Pg and Tf detected in moderate or patients with moderate or severe chronic periodontitis are significantly higher than that in healthy subjects, indicating that these bacteria have certain correlation with chronic periodontitis. The rate of Ec, Cr, Pg and Tf detected in severe chronic periodontitis are significantly higher than that in dental-induced gingivitis, suggesting their close relationship with the progress of periodontal disease.

Objective: This study aims to evaluate the antimicrobial activity of decapeptide, a novel antimicrobial peptide, against several major cariogenic and periodontopathogenic bacteria in vitro. METHODS In this study, we investigated the antimicrobial activity of decapeptide against Streptococcus mutans (S. mutans), Streptococcus sobrinus, Lactobacillus acidophilus, Streptococcus sanguis, Streptococcus gordonii, Actinomyces viscosus, Actinomyces naeslundii, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, and Saccharomyces albicans in vitro using the agar diffusion method and broth dilution method. Furthermore, a time-kill kinetic study of decapeptide against S. mutans was performed., Results: The results showed that decapeptide exhibited antimicrobial activity against various oral bacteria and fungi. The minimum inhibitory concentration (MIC) of main cariogenic bacteria ranged from 62.5 μg · mL(-1) to 125 μg · mL(-1), and the MIC of periodontopathogenic bacteria tested ranged from 250 μg · mL(-1) to 1,000 μg · mL(-1). Among the bacteria tested, decapeptide had a strong inhibitory effect on cariogenic S. mutans. Results of the time-kill kinetic studies showed that decapeptide reduced the viable counts of S. mutans by more than one order of magnitude after 20 min of incubation, and thoroughly killed S. mutans after 30 min. No viable cells could be detected after 24 h of incubation., Conclusion: This study suggest that decapeptide might have potential clinical application in treating dental caries by killing S. mutans within dental plaque.

Objective: To compare the clinical effect of Ginkgo biloba extract gel (Ginkgo biloba extract,EGB) and minocycline hydrochloride (Periocline) on periodontitis and their inhibition on putative periodontal pathogens., Methods: Thirty patients with moderate-to-severe periodontitis were selected. The patients were divided into an experimental group and a positive control group (minocycline hydrochloride). Supragingival and subgingival scaling were performed on all patients. Subgingival plaque samples were collected before treatment, 1 week, 2 months and 4 months after treatment. The four major periodontal pathogens Porphyromonas gingivalis (Pg), Bacteroides forsythus (Bf), Prevotella intermedia (Pi), Treponema denticola (Td) were detected by polymerase chain reaction. Clinical indexes plaque index (PLI), bleeding index (BI) and probing depth (PD), attachment loss (AL) were examined before treatment, 3 months and 6 months after treatment. The results were statistically analyzed., Results: The detection rates of the 4 periodontal pathogens were Td (83.3%), Tf (95.0%), Pi (80.0%), Pg (81.7% ) in experimental group and Td (83.3%), Tf (95.0%), Pi (80.0%), Pg (81.7%) in control group before treatment. The detection rates in experimental group were not significantly different with those in control group after treatment, except for the detection rate of Pg 1 week after treatment (P < 0.01, the detection of Pg was 56.7% in experimental group and 53.3% in control group 1 week after treatment). The PLI and BI were not significantly different between experimental group and control group after treatment (P > 0.05). The difference was statistically significant at 6 months after treatment [(3.5 ± 0.5) mm for experimental group and (3.2 ± 0.4) mm for control group, P = 0.00]. The mean of AL decreased with time. The difference was statistically significant at 6 months after treatment [ (4.5 ± 0.4) mm for experimental group and (4.3 ± 0.4) mm for control group at 6 months, P = 0.01]., Conclusions: The inhibition effects of EGB and minocycline hydrochloride were comparable for major periodontal pathogens within short term.

Objective: To investigate the expression of cytokines induced by Actinobacillus actinomycetemcomitans lipopolysaccharide (Aa-LPS) in monocytes/macrophages from different organs of rabbits., Methods: The peripheral mononuclear cells (Mo), alveolar macrophages (AM), peritoneal macrophages (PM) and Kupffer cells (KC) from five New Zealand rabbits were isolated respectively. Then the cells from different organs were stimulated with Escherichia coli (Ec)-LPS or Aa-LPS at the dose of 1 mg/L. After culture for 24 hours, the expression of tumor necrosis factor-α (TNF-α), interleukin (IL)6, IL-1β, IL-8 mRNA and protein were determined by real-time PCR and enzyme-linked immunosorbent assay respectively., Results: The monocytes/macrophages challenged by Ec-LPS or Aa-LPS expressed more cytokines both in mRNA and protein levels compared with the controls (P < 0.05). Among them, AM displayed the highest respond when encount with Aa-LPS, with the TNF-α, IL-6, IL-1β, IL-8 mRNA relative levels were (0.4719 ± 0.0171), (2.7895 ± 0.0669), (5.1527 ± 0.1190), (3.6785 ± 0.1836) and the proteins concentrations were (82.2 ± 5.4), (40.2 ± 2.0), (50 308.3 ± 445.0), (35 305.3 ± 1480.9) ng/L respectively. And the inducibility of Aa-LPS was stronger than that of Ec-LPS (P < 0.05). Meanwhile the cells from different organs showed discrepant response when exposed to Aa-LPS (P < 0.05). The results showed their abilities to secrete cytokines were in the sequence of AM > Mo > KC > PM., Conclusions: Aa-LPS influenced the expression of cytokines in monocytes/macrophages from different organs of rabbits.

Objective: To examine the expression of tumor necrosis factor in placenta of pregnant rats with chronic periodontitis., Methods: Twenty Wistar female rats were randomly divided into two groups, control (n = 8) and experimental group (n = 12). The periodontitis model was established in the experimental group. The females and males in the two groups got together four weeks later. Nineteen days after pregnancy all rats were executed and placenta collected. The delivery time and neonatal birth weight were recorded and the pathological changes of periodontal tissue observed. Tumor necrosis factor (TNF) expression was examined in placenta by real-time quantitative polymerase chain reaction analysis., Results: The animal model of chronic periodontitis was successfully established. Experimental group delivered 30 offspring and the control group 56 offspring. The average number of pups born alive per litter in experimental group (4.1 ± 2.2) was significantly lower than that in control group (9.2 ± 2.2), P < 0.05. The birth weight of pups in experimental group [(5.01 ± 0.43) g] was significantly lower than that in the control group [(5.79 ± 0.53) g], P < 0.05. The relative quantitative expression of TNF was (1.807 ± 0.265) in experimental group the and (1.003 ± 0.021) in the control group (P = 0.001)., Conclusions: Chronic periodontitis may be related to preterm low birth weight.

Unlabelled: PPURPOSE: To study the permanent planting of periodontal pathogens in the subgingival plaque of periodontitis patients with type 2 diabetes, and evaluate role of periodontal pathogens in chronic periodontitis and type 2 diabetes., Methods: One hundred and twenty subgingival plaque samples were collected from 90 severe periodontitis and 30 healthy periodontium patients with type 2 diabetes. Porphyromonas gingivalis (Pg), Aggregatibacer actinomycetemcomitans (Aa), Fusobacterium nucleatum (Fn), Prevotella intermedia (Pi), Tannerella forsythia (Tf) and Treponema denticola (Td) were taken as aim pathogens, polymerase chain reaction (PCR) detection was used to determine the prevalence of Pg, Aa, Fn, Pi, Tf, Td in the subgingival plaque samples.The average gradation(AVG)of positive band in the agarose gel electrophoresis was analyzed to determine the proportion of Pg, Aa, Fn, Pi, Tf, Td in the subgingival plaque. Chi-square test, t test and Pearson correlation were used to analyze the relationship between the periodontal pathogens and blood glucose and blood lipid., Results: The level of triglyceridey(TC) in Tf positive subjects was significantly higher than that in Tf negative subjects, the proportion of Tf in subgingival plaque was positively correlated with the value of fasting blood glucose(FBG). The proportion of Pg was positively correlated with the level of TC. The proportion of Pi was negatively correlated with the value of FBG and TC., Conclusion: Type 2 diabetes can affect the permanent planting of some putative periodontal pathogens. Supported by National"11th Five Year" Science and Technology Supporting Project (Grant No. 2007BAI18B02) and Science and Technology Research Plan of Liaoning Province(Grant No. 2007225007).

Objective: To explore the feasibility of methyl thiazolyl tetrazolium (MTT) colorimetric method and the applied condition for the normal bacteria in the mouth, as Streptococcus mutans (S. mutans), Streptococcus sanguis (S. sanguis), Haemophilus actinomycetemcomitans (H. actinomycetemcomitans)., Methods: Colony forming units (CFU) which was the standard antitheses was used to count bacteria. This study would gain some parameters by changing wavelength, reactive time, dosage and so on. MTT colorimetric method was applied in the counting of S. mutans, S. sanguis and H. actinomycetemcomitans., Results: When counting S. mutans, the best wavelength was 510 nm, the best range was 1.5 x 10(5) - 1.0 x 10(7) CFU x mL(-1). When counting S. sanguis, the best wavelength was 545 nm, the best range was 1.5 x 10(5) - 2.0 x 10(7) CFU x mL(-1). When counting H. actinomycetemcomitans, the best wavelength was 557 nm, the best range was 1.0 x 10(6) - 5.0 x 10(7) CFU x mL(-1). MTT colorimetric method can be used for different aged S. mutans, S. sanguis and H. actinomycetemcomitans., Conclusion: Oral bacteria could be counted by MTT colorimetric method, which is fast and convenient.

Purpose: To study whether B lymphocytes involve in bone resorption in periodontal disease by evaluating RANKL expression of B lymphocytes in immune response to aggregatibacter actinomycetemcomitans (Aa)., Methods: The expression of mRNA transcripts involved in day 1 and day 7 responses of cytokines in cultured rat splenocytes was determined by RT-PCR; The percentage of RANKL-expressing IgG positive cells by B cells in cultured rat splenocytes was measured by flow cytometry; and B lymphocytes capacity for induction of osteoclast differentiation was evaluated by TRAP staining. SPSS 10.0 software package was used for statistical analysis., Results: The expression of IL-4 and IL-10 in cultured cells was not changed in the presence of Aa on day 1, after culture for 7 days; The percentage of B lymphocytes, all RANKL mRNA transcripts and percentage of RANKL-expressing IgG positive cells were significantly increased in the presence, compared to the absence of Aa. These increases were considerably greater in cells isolated from immunized than non-immunized rats. B cells from Aa immunized rats significantly increased induction of osteoclast differentiation (P<0.01), and addition of human OPG-Fc into the culture significantly inhibited its induction (P<0.05), and was RANKL-independent., Conclusion: B lymphocytes contribute to bone resorption in periodontal disease through involving in the immune response to Aa, up-regulation of RANKL expression and increasing induction of osteoclast differentiation.

Objective: To evaluate the feasibility of identifying oral pathogenic bacteria by comparing the metabolic profiling of putative periodontal pathogens and try to find a convenient and rapid way to discriminate oral microorganisms., Methods: Suspensions of Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum with same density were prepared and cultured respectively at liquid BHI medium. Then the growth quantity was measured periodically through turbidimetry and the growth curves of the inoculated bacteria were completed. The culture solutions of stable growth phase were sampled and characterized by 1H-nuclear magnetic resonance 1H-NMR). The data of 1H-NMR spectroscope results were analyzed by principal components analysis (PCA)., Results: The PCA showed the obvious clustering phenomena and the points of three groups differentially centralized to three clusters. Therefore, the NMR-based metabonomics profiles could discriminate the three different kinds of bacteria., Conclusion: The metabonomics is a potential classable method to identify the oral pathogenic bacteria.

Objective: The ability of oral bacteria to adhere to tooth surface is associated with their pathogenicity. The objective of this study was to compare the ability of 4 strains of periodontal pathogens attaching to collagen-treated hydroxyapatite (C-HA) beads in order to evaluate the ability of the main periodontal pathogens to form the biofilm on root surface., Methods: The binding amount and binding percentage of 4 strains to C-HA were measured and compared by 3H-labeled binding assay. 4 strains of periodontal pathogens were Fusobacterium nucleatum (F. nucleatum) ATCC 10953, Porphyrin gingivalis (P. gingivalis) ATCC 33277, Prevotella intermedia (P. intermedia) ATCC 25611 and Hemophilic actinomycetemcomitans (H. actinomycetemcomitans) ATCC 29523., Results: The differences of the percentage of relative adherence between F. nucleatum ATCC 10953 and P. gingivalis ATCC 33277, as well as between H. actinomycetemcomitans ATCC 29523 and P. intermedia ATCC 25611 could not be observed. However, the percentage of relative adherence of F. nucleatum ATCC 10953 and P. gingivalis ATCC 33277 was higher than that of P. intermedia ATCC 25611 and H. actinomycetemcomitans ATCC 29523 (P<0.001), no matter cultured 24 h or 48 h. No significant difference of the percentage of the relative adherence of each stain between 24 h and 48 h cultured time could be found., Conclusion: F. nucleatum and P. gingivalis exhibited strong binding ability to C-HA. Their adherence to root surface may play an important role in their local aggregation, biofilm formation during the development and recurrence of the periodontitis.

Objective: To investigate the distribution of H. actinomycetemcomitans, P. gingivalis, P. intermedia, T. forsythensis and T. denticola in the subgingival plaque in the patients with chronic periodontitis., Methods: 27 patients with chronic periodontitis were included. Two of the deepest pockets of each patient were selected as the study sites. Semi-quantification of subgingival microorganism samples was analyzed by multiplex polymerase chain reaction and reverse hybridization assay., Results: P. gingivalis, P. intermedia, T. forsythensis and T. denticola were detected in a high proportion of examined sites(corresponding values were 98.15%, 92.59%, 100% and 98.15%), however, the proportion of H. actinomycetemcomitans was low (20.37%). The levels of P. gingivalis and T. forsythensis were higher than the other three microorganisms with statistical significance., Conclusion: The simultaneous infection of P. gingivalis, T. forsythensis, P. intermedia and T. denticola is found in the patients with chronic periodontitis, in which the levels of P. gingivalis and T. forsythensis are higher than the other two microorganisms.

Objective: To investigate the prevalence of H. actinomycetemcomitans in Chinese chronic periodontitis (CP) patients and periodontally healthy adults., Methods: 116 chronic periodontitis patients and 111 periodontally healthy adults were included. In each CP patient, subgingival plaque samples were collected from two sites of different molars with the greatest probing depth (PD) and one periodontally healthy site (PD < or =3 mm). The samples of periodontally healthy adults were obtained from the mesio-buccal site of one first upper molar. Bacteria DNA were extracted for detection of H. actinomycetemcomitans by 16S rRNA PCR., Results: The prevalence for H. actinomycetemcomitans of diseased sites (33.62%) was significantly higher than that of healthy sites from CP patients (0.86%) and the periodontally sites (0.90%) (P < 0.01). No significant difference was observed between male and female CP patients (P > 0.05). A decreasing trend of H. actinomycetemcomitans was observed as the age increased. And the pocket depth and clinical attachment losswas associated with the occurrence of H. actinomycetemcomitans in a positive mode. And H. actinomycetemcomitans was more often detected in the bleeding sites on probing., Conclusion: H. actinomycetemcomitans was more frequently detected in periodontitis sites than periodontally healthy sites. For CP patients, a higher prevalence was associated with the seriously involved sites than those moderate and mild implicated sites. H. actinomycetemcomitans is considered to be the one of the periopathogens involved in the etiology of chronic periodontitis.

Objective: To clone the recombinant fusion gene of Escherichia coli heat-liable enterotoxin B subunit (Ltb) and Actinobacillus actinomycetemcomitans fimbria associative protein (Fap)., Methods: Two couples of primers were designed for PCR according to the known sequence of ltb and fap. The ltb and fap gene were obtained by amplification PCR technique from plasmid EWD299 of Escherichia coli and Actinobacillus actinomycetemcomitans 310 DNA respectively, and fused them by PCR. The fusion gene ltb-fap were cloning into plasmid pET28a(+). The recombined plasmid pET28a ltb-fap was transformed into Escherichia coli DH5alpha. The recombinant was screened and identified by restriction enzyme and PCR. The cloned gene was sequenced., Results: The ltb-fap about 531bp in size was obtained successfully, and identified by PCR, restrictive enzyme and sequence analysis., Conclusion: The vector of pET28a ltb-fap was obtained.

Objective: The aim of this study was to investigate effects of immunodeficiency on the periodontal infection characters of the specific pathogens of juvenile periodontitis., Methods: A total of 36 immunodeficient guinea pigs produced by twice whole-body irradiation with 60Co were divided randomly into four groups, in which Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and A. actinomycetemcomitans with P. gingivalis were inoculated into the gingival sulcus of two mandibular incisors respectively. The pigs in the control group did not receive any inoculation. At 2, 3 and 6 weeks after inoculation, three animals in each group were sacrificed successively. Clinical and histological examinations were used to examine the changes in the periodontal tissues. The other 36 normal guinea pigs were divided into four groups and treated in a similar way described above., Results: Significant periodontal damages were noted in immunodeficient pigs inoculated with A. actinomycetemcomitans, P. gingivalis or A. actinomycetemcomitans and P. gingivalis in 2 and 3 weeks after bacterial inoculation. The damages were more severe than in the normal groups. The immunodeficient groups demonstrated larger numbers of osteoclasts than the normal groups (P < 0.05)., Conclusion: The loss of periodontal tissue in immunodeficient hosts is much serious than those with normal defence system, after they are infected with A. actinomycetemcomitans and P. gingivalis. Abnormal defence system in hosts may play an important role in onset and development of juvenile periodontitis.

Objective: To investigate the effect of stress on Guinea Pigs' periodontitis model., Methods: 24 periodontitis models of guinea pigs were provided by inoculating Actinobacillus actinomycetemcomitans (Aa) and Porphyromonas gingivalis (Pg) in the gingival sulcus. The guinea pigs were divided into two groups: stress group(stimulated with cold bath and fright) and control group(without stimulations). Three animals of each group were sacrificed successively at 1, 2, 4, 6 week after inoculation. Clinical and histological evaluation, cortisol concentration examinations, osteoclast and osteoblast numbers account were applied., Results: The cortisol concentration of stress group was significantly higher than that of control group at 1, 2, 4 week after stressed(P < 0.05 or P < 0.01). Pocket depth in stress group was significantly deeper than that in control group at 2, 4 week (P < 0.05), Compared with control group, the stress group demonstrated more active tissue damage and alveolar bone resorption. The bone repair in stress group was not as active as in control group. The osteoclast numbers in stress group was significantly higher than that in control group at 1, 4, 6 week (P < 0.05)., Conclusions: Stress could enhance the destruction of periodontal tissues infected by pathogenic bacteria and increase disease susceptibility. It was concluded that stress was a significant risk indicator for periodontitis.