Trend on dental caries status and its risk indicators in children aged 12 years in China: a multilevel analysis based on the repeated national cross-sectional surveys in 2005 and 2015.

BACKGROUND: This study aimed to explore the trend and risk indicators for dental caries of children aged 12 years in China based on national oral health survey data in 2005 and 2015. METHODS: Research data were from the two latest national oral health surveys conducted in mainland China, including 30 and 31 provinces, autonomous regions, and municipalities in 2005 and 2015, respectively. Children aged 12 years were clinically examined for dental caries and dental fluorosis according to the World Health Organization criteria. Sociodemographic characteristics and oral health-related behaviours were collected using questionnaires. Multilevel zero-inflated negative binomial regression model was used to investigate the association between dental caries severity and dental fluorosis, sociodemographic characteristics, and oral health-related behaviours. RESULTS: The final analyses included 12,350 and 27,818 children surveyed in 2005 and 2015, respectively. The standardized prevalence of dental caries increased from 27.05% (95% confidence interval [CI], 24.25-28.85) in 2005 to 37.92% (95% CI, 34.94-40.90) in 2015, and the respective standardized mean decayed, missing, filled teeth (DMFT) index scores increased from 0.50 (standard deviation [SD], 1.04) to 0.83 (SD, 1.45) (P < 0.001). Fujian province had the highest increase in dental caries, followed by Liaoning, Heilongjiang, Hainan, and Yunnan. Results revealed that children who were girls, more frequently experienced dental pain, and had more recent dental visits, had significantly higher DMFT scores after adjusting for the survey year and other variables (all P < 0.05). CONCLUSIONS: Dental caries of 12-year-old children in China deteriorated from 2005 to 2015, particularly in the northeast and southwest regions. Dental caries was associated with sex, dental pain, and dental service utilization.

Dynamic Observation of the Effect of Maternal Caries on the Oral Microbiota of Infants Aged 12-24 Months.

Aim: To provide a dynamic description of the oral microbial composition in mothers with and without dental caries and their children aging 12-24 months. Methodology: A total of 20 pairs of mothers and their children aged 12 months were included and followed up at 18 and 24 months of age. Ten mothers with dental caries(MEG) and their children(CEG) were in the exposure group, and ten caries-free mothers(MCG) and their children(CCG)in control group. Supragingival plaque biofilm samples were collected and DNA was extracted for bacterial 16S rRNA gene sequencing. Results: A total of 18 pairs completed follow-ups. At a 3% divergence level, the number of common operational taxonomic units found between the mothers and children increased as the children aged. Proteobacteria, Bacteroidetes, Firmicutes, Fusobacteria, and Actinobacteria accounted for more than 80% phyla of each group. A microbial community structure analysis showed that the differences between mothers and children were significant in all groups except for the MEG24 and CEG24 groups. Conclusions: Oral microbiota of children was more like their mothers' with increasing age, regardless of whether the mothers had dental caries. Mothers with dental caries may have a greater influence on the oral microbiota of children's than those without dental caries as children age.

Relationship between periodontal disease and male infertility: A case-control study.

OBJECTIVES: To compare the prevalence of chronic periodontitis between men who had semen abnormalities and those who had normozoospermia through a case-control study. MATERIALS AND METHODS: Male patients who visited the assisted reproduction clinic of a large general hospital and were diagnosed with semen abnormalities were included in the case group. The control group was composed of patients of the same clinic with normozoospermia. The semen analysis included sperm concentration, count and progressive and total motility, which were measured in the laboratory. A questionnaire and clinical periodontal examination were conducted for all participants. Logistic regression was performed to explore the relationship between chronic periodontitis and male infertility. RESULTS: A total of 192 participants were included: 63 participants (32.8%) had some type of semen abnormality (case group), while 129 participants (67.2%) had normozoospermia (control group). The case group had a significantly higher prevalence of moderate/severe periodontitis than the control group (33.3% vs. 17.8%, p = .012). The logistic regression showed that participants who had moderate/severe periodontitis had a greater chance of having semen abnormalities after adjusting for other confounding factors (OR = 3.377, p = .005). CONCLUSIONS: Periodontitis is associated with semen abnormalities and sperm motility in men.

Efficacy of an anhydrous stannous fluoride toothpaste for relief of dentine hypersensitivity: A randomized clinical study.

AIM: To compare efficacy of an anhydrous 0.454% w/w stannous fluoride/sodium fluoride toothpaste (Test) versus a sodium monofluorophosphate toothpaste (Negative control) and a stannous chloride/sodium fluoride toothpaste (Positive control) for dentine hypersensitivity relief after 8 weeks' twice-daily use. MATERIALS AND METHODS: In this randomized, examiner-blind, stratified, parallel study, primary and secondary efficacy variables were mean changes in Schiff score (evaporative [air] sensitivity) and tactile threshold (Yeaple probe), respectively, from baseline to Week 8 between Test (n = 62) and Negative control (n = 62). Test and Positive control (n = 61) comparisons were exploratory objectives. RESULTS: All groups significantly improved from baseline on both dentine hypersensitivity measures (p < .0001). Difference between adjusted mean changes from baseline in Schiff sensitivity scores at Week 8 for Test versus Negative control groups was 0.19 (95% CI 0.002, 0.374), in favour of the Negative control (p = .0476; 12.57% difference). Difference in tactile threshold was -7.20 g (95% CI -16.376, 1.975), and this was not statistically significant (p = .3715; -21.83% difference). Test group showed no significant difference versus Positive control for either measure. Toothpastes were generally well tolerated. CONCLUSION: While twice-daily use of Test toothpaste significantly reduced dentine hypersensitivity from baseline, there was no significant advantage over negative or positive controls. STUDY REGISTRATION: Clinicaltrials.gov; NCT03310268.

Plaque biofilm microbial diversity in infants aged 12 months and their mothers with or without dental caries: a pilot study.

BACKGROUND: A number of studies on oral microbial diversity of early childhood caries (ECC) have tended to focus on mid- or late-stage of ECC, with a lack of research into early stage of tooth eruption and maternal influence. The aims of this study are to compare the supragingival plaque biofilm microbiota diversity between mothers with or without dental caries and their 12-month-old infants, and to explore the relationship of microbial diversity between infants and their mothers, using sequencing analysis. METHODS: Supragingival plaque biofilm samples were collected from 20 pairs of mothers and their infants aged 12 months (10 mothers with dental caries and their 10 infants vs. 10 caries-free mothers and their 10 infants). The basic information of the mothers and infants had been collected through self-completed questionnaire. Pooled plaque biofilm DNA was extracted and DNA amplicons of the V4-V5 hypervariable region of the bacterial 16S rRNA gene were generated. Ilumina Miseq PE300 was used for 16S rRNA sequencing. RESULTS: The results showed that high bacterial diversity was noted in the plaque biofilm of infants and their mothers with or without dental caries (dental caries mothers vs. caries-free mothers: 774 operational taxonomical units (OTUs) vs. 761 OTUs at a 3% divergence; infants whose mothers have dental caries vs. infants whose mothers are caries-free: 815 OTUs vs. 684 OTUs at 3% divergence). The Shannon microbial diversity index showed no statistically significant differences both on infants and their mothers between two groups (p > 0.05). Mother's microbial diversity was higher than infants' based on Shannon index (p < 0.05). Significant positive correlations were found between mothers' and their infants' Shannon index (r = 0.656, p = 0.002). CONCLUSION: Oral microbial diversity is significantly different between mothers and infants regardless of dental caries status, but no significant difference was found between mothers with and without dental caries or between their infants. Mother's oral microbial diversity has an overall impact on the infants aged 12 months.

Establishment and Development of Oral Microflora in 12-24 Month-Old Toddlers Monitored by High-Throughput Sequencing.

A cohort study was conducted to evaluate oral microbial diversity among toddlers aged 12-24 months, and to describe the dynamic processes of colonization, development, and stabilization of the oral microflora during tooth eruption using high-throughput sequencing technology. A total of 20 healthy toddlers aged 12 months were included at baseline and followed up through 18-24 months. Clinical oral examinations of dental caries status and visible plaque index were carried out at three follow-up time points. Pooled supragingival plaque biofilm samples were also collected at ages 12, 18, and 24 months. Plaque biofilm DNA was extracted and analyzed by MiSeq sequencing. A total of 18 toddlers completed three follow-ups. At 12 months of age, all the toddlers only had eruption of the anterior teeth, without dental caries. At ages 18 and 24 months, one and two toddlers showed two and three teeth with carious white spots, respectively. Depth, Good's coverage, and sample size of sequencing were reasonable. The dominant bacterial genera in the oral cavity of 12-month-old toddlers were Capnocytophaga, Neisseria, Streptococcus, Kingella, and Leptotrichia; the oral microflora composition was relatively stable by 18 months of age and included unclassified Enterobacteriaceae, Selenomonas, Prevotella, Leptotrichia, and Veillonella as the dominant genera; unclassified Enterobacteriaceae, Streptococcus, Neisseria, Leptotrichia, and Selenomonas were the dominant genera by 24 months. There were significant differences among microbial compositions in the oral cavities of 12, 18, and 24-month-old toddlers, with relatively small differences observed between the 18 and 24 months samples. In conclusion, oral microbial community of toddlers showed a trend of dynamic development. Significant differences in oral microbial diversity among toddlers aged 12-24 months were observed, while the microbial diversity differences among toddlers aged 18-24 months tended to be more similar. The findings indicated that the oral microbial community gradually matures and tends to stabilize with the growth and development of toddlers.

Tooth whitening evaluation of blue covarine containing toothpastes.

OBJECTIVES: To measure the tooth whitening effects delivered immediately after brushing with silica-based toothpastes containing blue covarine in vitro and in vivo. METHODS: Salivary pellicle coated human extracted teeth were brushed with either a slurry of a toothpaste containing blue covarine (BC), a formulation containing an increased level of blue covarine (BC+) or a negative control toothpaste containing no blue covarine. The colour of the specimens were measured in vitro using either a Minolta chromameter or a VITA Easyshade spectrophotometer, before and after brushing and changes in CIELAB values and tooth Whiteness Index (WIO) values calculated. In a double-blind cross-over clinical study, subjects brushed with either BC or BC+ toothpaste and tooth colour changes were measured with a digital image analysis system. RESULTS: The in vitro studies demonstrated that toothpastes containing blue covarine gave a significantly (p<0.05) greater change in b* and WIO values than the negative control toothpaste; the BC+ toothpaste gave a significantly greater increase in b* and WIO values than the BC toothpaste, and BC+ gave a significant increase in shade change versus the negative control. Clinical results showed that BC and BC+ gave a significant reduction in b* (p<0.0001) and increase in WIO (p<0.0001) from baseline indicating significant tooth whitening had occurred. The parameter changes were significantly greater when brushing with the BC+ toothpaste than with the BC toothpaste (WIO p=0.006; b* p=0.013). CONCLUSIONS: Toothpastes containing blue covarine gave a statistically significant reduction in tooth yellowness and improvement in tooth whiteness immediately after brushing in both in vitro and clinical studies. In addition, the higher concentration blue covarine toothpaste gave statistically significant greater tooth whitening benefits than the lower concentration blue covarine toothpaste. CLINICAL SIGNIFICANCE: The silica-based toothpastes containing blue covarine evaluated in the current study gave tooth whitening benefits immediately after one brush.

In vitro and clinical evaluation of optical tooth whitening toothpastes.

OBJECTIVES: To measure tooth whitening effects delivered immediately after brushing with silica-based toothpastes containing either blue covarine or a combination of blue covarine and FD&C Blue No. 1 in vitro and in vivo. METHODS: Salivary pellicle coated human extracted teeth were brushed with either a slurry of a toothpaste containing blue covarine (BC) or a formulation containing a matched level of blue covarine and FD&C Blue No.1 (BC+D). The colour of the specimens were measured in vitro using a colorimeter, before and after brushing and changes in CIELAB and tooth Whiteness Index (WIO) values calculated. In a double-blind cross-over clinical study, subjects brushed with BC toothpaste, a toothpaste containing increased levels of blue covarine (BC+) or BC+D toothpaste and tooth colour changes were measured with a digital image analysis system. RESULTS: The in vitro study demonstrated that BC+D gave a significantly (p=0.002) greater change in WIO value than BC. Clinical results showed that BC, BC+ and BC+D gave a significant increase in WIO (p<0.0001) from baseline. The WIO change was significantly greater when brushing with BC+D toothpaste than with either toothpaste BC (p<0.0001) or BC+ (p<0.05). CONCLUSIONS: Toothpastes containing blue covarine or a combination of blue covarine and FD&C Blue No. 1 gave a statistically significant improvement in tooth whiteness immediately after brushing in both in vitro and clinical studies. In addition, the toothpaste containing both blue covarine and FD&C Blue No. 1 gave statistically significant greater tooth whitening from baseline than the blue covarine containing toothpastes. CLINICAL SIGNIFICANCE: The silica-based toothpastes containing blue covarine or a combination of blue covarine and FD&C Blue No. 1 evaluated in the current study gave significant tooth whitening benefits immediately after one brush.

[A survey on knowledge, attitude and practice related to evidence-based dentistry among dental students].

PURPOSE: To investigate the knowledge, attitude and practice related to evidence-based dentistry among dental students, and to provide a reference for targeted evidence-based dentistry teaching and practice evidence-based dentistry in dental students. METHODS: Dental students who attended the internship in Shanghai Ninth People's Hospital and Pudong People's Hospital were invited to attend this survey. Information on knowledge, attitude and practices related evidence-based dentistry was collected through questionnaires. SPSS 21.0 software package was used for data analysis. RESULTS: A total of 62 dental students attended this survey. Evidence-based dentistry related knowledge and attitude scores were 5.5±1.9 and 5.1±1.0, respectively. Over three quarters of students took courses on evidence-based medicine, while around half of students (56.5%) self-reported that they knew little about evidence-based medicine. 70.5% students practiced evidence-based dentistry less than once in the process of clinical decision making per week. The majority of students (80.3%) used MEDLINE or other databases to search for practice-related literature less than once per week. 63.9% students used practice guideline. The top three barriers to practice evidence-based dentistry were lack of information resources, insufficient time and lack of search skills. CONCLUSIONS: Evidence-based dentistry related knowledge and practice among dental students is deficient, whereas they hold positive attitude on practice. The top three barriers to practice evidence-based dentistry are lack of information resources, insufficient time and lack of search skills.

[Clinical study on the effect of anti-gingivitis IgY toothpaste in control of gingivitis and dental plaque].

PURPOSE: To observe the effect of anti-gingivitis IgY toothpaste in control of gingivitis and plaque. METHODS: The study was a double-blind, randomized, parallel-controlled clinical trail with a total of 100 subjects who were divided into two groups, experimental group and control group. The subjects in experimental group used anti-gingivitis IgY toothpaste to brush twice daily for 3 minutes, and the subjects in control group used none anti-gingivitis IgY toothpaste. The examiner recorded GI, PI and BOP index of all subjects at the baseline, 6-weeks and 12-weeks. SPSS21.0 software package was used for statistical analysis. RESULTS: Twelve weeks later, there were significant differences in GI and BOP between the two groups. Yet no significant difference was found in PI. CONCLUSIONS: Anti-gingivitis IgY toothpaste is effective in control of gingivitis.

Putative periodontopathic bacteria and herpesviruses in pregnant women: a case-control study.

Little is known about herpesvirus and putative periodontopathic bacteria in maternal chronic periodontitis. The present case-control study aimed to explore the potential relationship between putative periodontopathic bacteria and herpesviruses in maternal chronic periodontitis.Saliva samples were collected from 36 pregnant women with chronic periodontitis (cases) and 36 pregnant women with healthy periodontal status (controls). Six putative periodontopathic bacteria (Porphyromonas gingivalis [Pg], Aggregatibacer actinomycetemcomitans [Aa], Fusobacterium nucleatum [Fn], Prevotella intermedia [Pi], Tannerella forsythia [Tf], and Treponema denticola [Td]) and three herpesviruses (Epstein-Barr virus [EBV], human cytomegalovirus [HCMV], and herpes simplex virus [HSV]) were detected. Socio-demographic data and oral health related behaviors, and salivary estradiol and progesterone levels were also collected. The results showed no significant differences in socio-demographic background, oral health related behaviors, and salivary estradiol and progesterone levels between the two groups (all P > 0.05). The detection rates of included periodontopathic microorganisms were not significantly different between the two groups (all P > 0.05), but the coinfection rate of EBV and Pg was significantly higher in the case group than in the control group (P = 0.028). EBV and Pg coinfection may promote the development of chronic periodontitis among pregnant women.

[Preparation and identification of polyclonal antibody of Streptococcus salivarius 57.I urease].

PURPOSE: To prepare and identify polyclonal antibody of Streptococcus salivarius 57.I urease. METHODS: The biggest structural subunit of Streptococcus salivarius 57.I urease, UreC, was obtained by gene clone, IPTG-induced expression, and purification through affinity chromatography. Anti-sera and polyclonal antibody were raised by immunizing rabbits with purified UreC. Western blot was utilized to detect the specific combination of polyclonal antibody with UreC. RESULTS: Purified UreC protein was prepared and used as antigen to immunize rabbits. Polyclonal antibody was obtained， and Western blot displayed a specific band of the polyclonal antibody with UreC about 62 kD as anticipated. CONCLUSIONS: Polyclonal antibody against Streptococcus salivarius 57.I urease is obtained, which provides an important tool to explore the function of urease and its relationship with dental caries.

Dental erosion among children aged 3-6 years and its associated indicators.

OBJECTIVES: To analyze the status quo of dental erosion in 3- to 6-year-old children in Shanghai. METHODS: A stratified, cluster, multistage random sampling methods was applied to 3- to 6-year-old children in Shanghai in 2012. Both questionnaire and clinical oral examination were performed in the survey. The questionnaire included general information, such as age, gender, parental education, dietary habit, oral health behavior, general medical health, and socioeconomic status. The clinical examination focused on the eroded tooth surface and dental erosion extent. SPSS v19.0 software package was utilized for statistical analysis. RESULTS: A total of 1,837 children aged 3-6 years were randomly selected in Shanghai. The overall dental erosion prevalence was 15.1 percent. Among different age groups, a relatively high prevalence of 17.1 percent was found in the 4-year-old group, and a relatively low prevalence of 12.0 percent was observed in the 3-year-old group. Surprisingly, there was no significant difference among the four age groups. The occurrence of dental erosion was influenced by habits of vinegar/coffee/tea consumption, mother's educational background, birthplace, and regurgitation (P < 0.05). CONCLUSION: The dental erosion prevalence in 3- to 6-year-old children in Shanghai appears to be close to that of other Chinese provinces as well as that observed in most of surveys carried out in different parts of the world. Efforts should be made to raise public awareness about the disease. Moreover, further studies targeted to explore the relationship between dental erosion and risk factors are needed. It is also necessary to establish a unified diagnostic standard for future epidemiological investigations.

Mode of action studies on the formation of enamel minerals from a novel toothpaste containing calcium silicate and sodium phosphate salts.

OBJECTIVES: To investigate in vitro and in situ the deposition and formation of hydroxyapatite (HAP) on enamel surfaces following brushing with a novel toothpaste containing calcium silicate (CaSi), sodium phosphate salts and fluoride. METHODS: Polished enamel blocks were brushed in vitro with a slurry of the CaSi toothpaste. After one brush and four weeks simulated brushing the enamel surfaces were analysed. In an in situ protocol, enamel blocks were attached to first or second molar teeth of healthy subjects, exposed to 4 weeks twice per day brushing with the CaSi toothpaste and then analysed. The surface deposits were analysed using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). In addition, the CaSi toothpaste was slurried in simulated oral fluid (SOF) over a 3 hour period and the solids were isolated and analysed by Fourier transform infrared spectroscopy (FTIR). RESULTS: The FTIR study demonstrated that calcium phosphate phases had formed and these became increasingly crystalline over 3 hours. CaSi was deposited onto enamel surfaces following one brushing with the toothpaste in vitro.The deposited particles showed evidence of HAP crystalline phases associated with the CaSi. Following 4 weeks brushing in vitro, the deposition increased and analyses showed that the deposited material was HAP. These results were confirmed by the in situ study. CONCLUSIONS: Calcium silicate can be deposited onto enamel surfaces from a novel toothpaste formulation where it can form the enamel mineral HAP. CLINICAL SIGNIFICANCE: A novel toothpaste formulation containing CaSi can form HAP on enamel surfaces. The potential of this technology is for a novel approach to the repair of demineralised enamel and the protection of enamel during acid exposure.

[Relationship between ureolytic activity expression of Streptococcus salivarius urease genes ureIABCEFGD in Escherichia coli and nickel ions].

PURPOSE: To obtain the clone of Streptococcus salivarius 57.I urease genes ureIABCEFGD and investigate the relationship between ureolytic activity expression of this clone in Escherichia coli and nickel ions. METHODS: The target gene was cloned by polymerase chain reaction in 2 parts separately. Then, 2 plasmids were digested by specific restriction enzymes and ligated together. The obtained plasmids were subjected to nucleotide sequence analysis and transformed into E.coli TG-1. The recombinant E.coli was added without or with different level of NiCl2. The amount of ammonia generated by ureolytic activity of each sample was measured by Nessler's assay. SPSS 17.0 software package was used for correlation analysis. RESULTS: The clone of urease genes ureIABCEFGD was proved by sequence analysis and BLAST search. The amount of ammonia generated by the recombinant strain had a positive correlation with the level of NiCl2(r=0.9714,P<0.01). When the level of NiCl2 was 50 µmol/L, the amount of ammonia reached maximum and would have little variance despite the increase of NiCl2 level. CONCLUSIONS: Ureolytic activity expression of ureIABCEFGD has a positive correlation with the level of added NiCl2 not exceeding 50 µmol/L. The present clone can be used to further investigate the regulation of the ureolytic activity expression of Streptococcus salivarius urease gene. Supported by Natural Science Foundation of Shanghai Municipality(08ZR1416800) and Research Fund of Science and Technology Committee of Shanghai Municipality(11411950900).

[Practice and experience in early clinical education of dental students in preventive dentistry].

To help dental students acquaint the medical environment, doctor-patient communication and relationship, early clinic education was arranged in our college of stomatology. The interesting topics were chosen to enhance the learning enthusiasm of the students in the teaching practice of preventive dentistry. Students were encouraged to practice the skill of doctor-patient communication. To obtain the satisfactory teaching effect and aim, it was important to pay attention to the aspects in the groups and clinical practice. Early clinic education in preventive dentistry help the students understand the specialty of preventive dentistry.

A randomized trial on the inhibitory effect of chewing gum containing tea polyphenol on caries.

OBJECTIVE: The purpose of the study was to determine the cariostatic potential of a chewing gum containing tea polyphenol. STUDY DESIGN: A total of 157 schoolchildren aged 8-9 years were randomly allocated into three groups. Two groups received chewing gum with or without tea polyphenol. A third group did not receive any chewing gum. A single examiner assessed the caries status for all participates at baseline, 12 months and 24 months. A one-way analysis of variance (ANOVA) was performed to evaluate differences among the groups at each interval The Chi-square test was used to compare the caries-free rate among the three groups. RESULTS: The mean DMFT increment was 0.17 for the polyphenol gum group, 0.60 for the control gum group, and 1.15 for the no gum group. Children who chewed gum containing tea polyphenol had a significantly lower mean DMFS increment over the 24-month period than did the other two groups (p < 0.05). The caries-free rate in the polyphenol gum group was significantly higher than that in the other two groups (p < 0.05) after two years. CONCLUSION: These findings indicated that the oral application of chewing gum with tea polyphenol has an inhibitory effect on dental caries.

[Cloning and expression of Streptococcus salivarius urease gene in Escherichia coli].

OBJECTIVE: To clone Streptococcus salivarius (Ss) 57. I urease gene, which can express ureolytic activity in Escherichia coli (Ec) without adding extra nickel ions. METHODS: Urease gene was cloned by polymerase chain reaction in three separate parts. The three separate plasmids were digested by specific restriction enzymes and ligated together. The expression of the complete urease gene in Ec was detected by phenol red assay and pH analysis. RESULTS: Urease gene of Ss 57.I was eventually cloned and proved correct. Urease activity of the obtained clone was positive in Ec. Without adding extra NiCl(2), the recombinant Ec could hydrolyze urea to produce ammonia, resulting in the increase of pH value. CONCLUSIONS: The clone of Ss urease gene obtained in this study could express ureolytic activity in Ec without adding extra nickel ions. The current clone can be used to construct ureolytic effector strain used in replacement therapy in caries prevention.

[The relationship of halitosis and Helicobacter pylori].

PURPOSE: The aim of the study was to investigate the relationship between halitosis and Helicobacter pylori infection in stomach. METHODS: Fifty subjects without periodontal diseases and systematic disease (exclude gastrointestinal diseases) were included. Infection of H.pylori was diagnosed by biopsy and (14)C-urea breath test. SPSS11.5 software package was used to analyze the data. RESULTS: All the subjects were periodontal healthy according to the periodontal index. The prevalence of H.pylori infection in halitosis subjects was significantly higher than that in the normal subjects (57.1% VS 18.2%, P<0.01). Logistic regression analysis showed that H.pylori was the only significant variable in the equation(P<0.05). CONCLUSIONS: H.pylori in stomach may be involved in the presence of halitosis in periodontal healthy subjects.

[Effect of two kinds of chewing gums on dental plaque pH].

PURPOSE: The aim of the study was to evaluate the change of plaque pH after chewing 2 kinds of gums. METHODS: The investigation consisted of 8 healthy subjects (aged 23-27 years, 4 males and 4 females) who refrained from toothbrushing for 24 hours before the test. The pH of dental plaque was measured using a Beetrode pH microelectrode before and after sucrose challenge with a 10% sucrose solutions at 5, 10, 15, 20 minutes as the baseline data. One week later the pH of dental plaque was measured again before the rinse and then the subjects rinsed with a 10% sucrose solutions. After 1 minute the sugar-free chewing gum was given and started to chew for 5, 10, 15, 20 minutes. The pH of dental plaque was measured at the same time on the non-chewing side. One week later the same test was carried out but the chewing gum was changed to tea polyphenol gum. Dental plaque pH value were analyzed by one-way ANOVA and SNK using SPSS 10.0 software package. RESULTS: Compared with the baseline chewed either tea polyphenol gum or sugar-free gum could increase the plaque pH recovery due to the sucrose rinsing challenge and it could maintain the dental plaque pH above the resting value. There was no statistically significant difference between tea polyphenol gum and sugar-free gum (P>0.05). CONCLUSION: Both gums can increase the plaque pH and decrease the risk of caries.