[Effect of fluoride on the viability and apoptosis of ameloblasts in vitro].

PURPOSE: To evaluate the effect of fluoride on viability of rat ameloblasts in vitro. METHODS: The ameloblasts of rat was exposed to different concentrations of NaF (0, 0.4, 0.8, 1.6, 3.2, 6.4 mmol/L) for 24, 48 and 72 hours. CCK-8 assays were performed to measure the cells proliferation; The morphology of apoptosis was observed by Hoechst 33258 staining and the rate of apoptosis was determined by flow cytometry. The data was analyzed using SPSS 13.0 software package. RESULTS: (1)The proliferation of ameloblasts was increased when concentrations of NaF between 0.4 mmol/L and 0.8 mmol/L, whereas inhibited at 1.6 mmol/L NaF and above. The effects were in time-dependent manner.(2)Cells in the 1.6 mmol/L NaF groups showed unclear karyorrhexis and apoptotic cell morphology. The effects were in concentration-dependent manner. CONCLUSIONS: (1)Fluoride has two-phase effects to ameloblasts: At low doses, it promoted cell proliferation while at high doses it had negative effects. (2)1.6 mmol/L NaF could induce apoptosis of ameloblasts.

[The effect of fluoride on the metabolism of teeth and bone in rats].

PURPOSE: To investigate the effect of fluoride on the metabolism of teeth and bone in rats, and to probe the mechanism of pathogenesis of dental fluorosis. METHODS: A total of 48 Wistar rats were randomly and equally divided into 4 groups including control group (distilled water), low-dose group(NaF,50 mg/L), medium-dose group (NaF,100 mg/L) and high-dose group (NaF, 150 mg/L). After 8 weeks, the rats were sacrificed under anesthesia, and serums were collected. The biochemical technique was used to test serum calcium. Changes in the fluorine content in serums and teeth of each group were analyzed with fluoride ion selective electrode method. Radioimmunoassay was employed to detect the levels of osteocalcin (OC), parathormone (PTH) and calcitonin (CT), respectively. SPSS13.0 software package was used for statistical analysis. RESULTS: The fluorine content in serum and teeth in the fluoride group were significantly higher than that of the control group (P<0.05), and increased with the increasing concentrations (F value was 11.234 and 275.148 respectively, P<0.01). The level of calcium in serum (F=3.906, P<0.05) in the fluoride group was significantly lower than in the control group. The level of PTH and OC in serum in medium and high-dose group were significantly higher than in the control group (P<0.01), with the level of CT in high-dose group decreased significantly (P<0.01). The differences of the level of OC, PTH, CT between groups were significant (F value was 8.548, 3.801 and 5.121 respectively, P<0.05). CONCLUSIONS: Fluoride affects the metabolism of teeth and bone in rats and OC, PTH, CT plays a key role in the pathogenesis of dental fluorosis.

[Investigation of dental manpower in non-public dental institutions in Liaoning province].

PURPOSE: To investigate the non-public oral medical institutions in Liaoning province in 2011, and to analyze the status of dental manpower in non-public dental institutions in Liaoning province. METHODS: A mass survey on dental manpower was made in non-public dental institutions in Liaoning province in 2011 by means of questionnaire investigation, which included the institution type, dental devices, and the number, structure, composition, distribution of dental manpower in non-public dental institutions in Liaoning province. Data was entered with EpiData 3.0 and analyzed with SPSS 13.0 software package. RESULTS: There were 1649 non-public dental institutions with 3132 dentists, 1265 nurses, 540 technicians and 3490 dental chairs in Liaoning province. 85.69% of the dental manpower were young and middle-aged. 33.17% of the dentists had primary professional titles, 42.53% of them had college degree and 87.96% of the dentists was general dentistry. In the dental auxiliaries, the primary professional title accounted for the majority. 95.97% of the nurses majored in general dentistry and 60.40% of the nurses' educational background were below junior college degree. 72.59% of the technicians majored in prosthetic dentistry and 67.78% of their educational background were below junior college degree. The ratio of the dentists to nurses to technicians was 6:2:1. The ratio of the nurses to dental chairs was 1:2.76. CONCLUSIONS: The distribution and composition of dental manpower are not reasonable in non-public dental institutions in Liaoning province. We should strengthen effective utilization of oral health resources and the oral health service ability of non -public dental institutions in Liaoning province. Supported by Key Science and Technology Projects of Liaoning Province (2012225015).

Distribution of enteroviruses in hospitalized children with hand, foot and mouth disease and relationship between pathogens and nervous system complications.

BACKGROUND: To explore the relationship between enteroviruses and hospitalized children with hand, foot and mouth disease (HFMD) complicated with nervous system disease. 234 hospitalized HFMD patients treated in Shengjing Hospital, Liaoning Province were analyzed retrospectively. Based on the presence and severity of nervous system disease, the patients were grouped as follows: general patients, severely ill patients, critically ill patients and fatal patients. Based on the detected pathogen, the patients were grouped as follows: Enterovirus 71 (EV71) infection, coxsackie A16 (CA16) infection and other enterovirus (OE) infection. RESULTS: Of the 423 hospitalized patients, most were admitted in July 2010(129/423, 30.5%). Enteroviruses were detected in 177(41.8%). 272/423 patients were male (64.3%), and fatal patients had the greatest proportion of male patients (p < 0.05). EV71 infection was found in 89/423 patients (21%). CA16 infection was detected in 8/423 patients (16.1%). Compared to group CA16, patients in group EV71 were hospitalized earlier, and the duration of hospitalization was longer (p < 0.05). Of the 92 patients with nervous system damage, 65 were infected with EV71 and 19 were infected with CA16. Among these CA16 infected patients, 2 had brainstem encephalitis and 1 had AFP. There were more patients with nervous system dysfunction in group EV71 than in groups CA16 or OE (p < 0.05). The 5 fatalities all occurred in group EV71 patients (p < 0.05). Infection with EV71 was most likely to cause neurogenic pulmonary edema (p < 0.05). Patients in group EV71 had a higher rate of suffering from coma and limb movement disorder than patients in groups CA16 or OE (p < 0.05). CONCLUSION: The disease progresses faster in EV71-infected HFMD patients. These patients are more likely to suffer nervous system damage, neurogenic pulmonary edema, severe sequelae or death. CA16 and other enteroviruses can also cause HFMD with severe nervous system complications.

[Investigation of the medical institutions of stomatology and dental manpower distribution in Liaoning province].

PURPOSE: The aim of this investigation was to determine and analyze the distribution of the medical institutions of stomatology and dental manpower in Liaoning province. METHODS: The data of institutions and manpower was collected by mass examination using tables filled by every institution and personally. Epidata 3.02 database was used to input the data and statistical analysis was performed using the SPSS12.0 software package. RESULTS: The results showed that there were 2155 dental institutions and 5617 dentists in Liaoning province. Among all the institutes, 71.0% was private clinics. About 80.5% of institutions and 87.8% of dentists were in the urban area, which was significantly higher than the percent of dentists working in the rural area. The ratio between dentists and the general population was about 13.02/10 million. There were fewer dental auxiliary in dental institutions, the ratio between dentists, nurses and dental technician was 6:2:1. The title and degree of the dentists in the rural area were lower than those in urban area, but the dentists in the rural area provided service for a large population. CONCLUSION: The results suggest that the distribution of oral health resource in Liaoning province should be rationally readjusted, and continuing education and training should be strengthened in order to improve the efficiency of oral health service and social health justice. Supported by Key Medical Professional Construction Project of Liaoning Province (Grant No.200809).

[The investigation of dental caries among elderly people in northeast of China].

OBJECTIVE: To study the dental caries status of the 65-74 years old people in northeast of China, analyze the distribution of caries in the group of people, and provide scientific basis for establishing the oral health care policies. METHODS: The representative samples were selected by multi-stage, stratified and random sampling from the three province of northeast of China. Dental caries of 2 364 people aged 65-74 were recorded according to WHO criteria. SPSS 12.0 software was used to analyze the data. RESULTS: 1) Among 2,364 elderly people in northeast of China, the prevalence of dental caries was 67.5% and DFT was 2.68, the composition of filling was 10.82%. 2) The prevalence of coronal caries was 66.4% and DFT was 2.55. The composition of filling was 11.37%. 3) The prevalence of root surface caries was 48.4% and DFT was 1.64. The composition of filling was only 1.8%. CONCLUSION: The prevalence of dental caries among elderly people in northeast of China is still very high, and the filling rate is low. The community based oral health promotion should be strengthened and preventive-oriented oral health care systems are needed in northeast of China.

[A sampled investigation on tooth loss of middle-aged and elders in Northeast China].

PURPOSE: To investigate the current status and the distribution of tooth loss in middle-aged people and elders in Northeast China, and provide scientific basis for the establishment of oral health care policies. METHODS: An equal-sized stratified multi-stage random sampling design was applied according to the third national oral health investigation of epidemiology, tooth loss was examined among 4752 people aged 35-44 and 65-74 in northeast China. The data were analyzed with SPSS13.0 statistical software for independent-sample t test and Chi-square test. RESULTS: Of all the subjects, 3135 people had tooth loss, the rate of tooth loss was 66.80%, mean tooth loss was 4.95; 392 persons were half edentulous, the rate of edentulous jaw was 8.35%, 223 persons were edentulous, the rate edentulous jaw was 4.75%. Statistical analysis showed tooth loss rate in females was significantly higher than that in males(P<0.05). There was significantly difference of tooth loss between city and rural area (P<0.05). There was significant difference in the amount and rate of tooth loss between Jilin Province and Liaoning Province, and Jilin Province and Heilongjiang Province as well (P<0.05). CONCLUSIONS: The tooth loss rate is very high in middle-aged people and elders in Northeast China. Measures should be taken to prevent dental caries and periodontal disease in these population so that to promote the status of middle-aged people and elders on oral health and to improve their quality of life.

[Difference between dental caries and oral health behavior of family in primary dentition].

OBJECTIVE: To study the dental caries status in the primary dentition of 5-year-old children and analyze the difference of oral health behavior of family between urban and rural in Liaoning province. METHODS: The representative samples were selected by multi-stage, stratified and random sampling from Liaoning province. Dental caries of 792 children at five years were recorded according to World Health Organization criteria. The questionnaries were finished by 396 parents of the children and analyzed the oral health behavior of family in urban and rural by chi-squre test. RESULTS: The prevalence and dmft of dental caries of 5-year-old children in Liaoning province was 73.86% and 4.38, respectively. The prevalence of dental caries in 5-year-old children was 64.14% in urban and 83.59% in rural. There was significant difference on the consumption of sweets, chocolate, water with sugar and beverage between the children in urban and rural. More urban children had good toothbrushing behavior such as the time of beginning brush tooth, the frequency of brushing and daily use of fluoridated toothpaste compared with the rural children. The parents in urban had high level of education and incomes and there were more children in urban have regular dental visit pattern than in rural. CONCLUSION: This study has shown that there is an urgent need for the implementation of a systematic education on oral health behavior of family on rural children in Liaoning province.

[Analysis of the first permanent molar caries epidemiological investigation in area of northeast China].

OBJECTIVE: To survey the tooth decay of the first molars among the people in area of northeast China in order to provide the foundation for prevention and treatment strategies of caries. METHODS: According to the third national oral health investigation of epidemiology, the dental caries of first permanent molars were examined among 9394 people aged 5, 12, 35-44 and 65-74 in northeast China. The data were analyzed by SPSS 13.0 statistical software. Dental caries prevalence rate and DMFT (dmft) of first permanent molar were calculated. RESULTS: The prevalence of crown and root dental caries in northeast China were 26.86% and 3.81% respectively, mean DMFT (dmft) of crown and root dental caries were 0.41 and 0.04 respectively. There were significant differences of dental caries among provinces in northeast China. Mandibular first molar suffered from dental caries easily. The prevalence of caries of female was higher than that of male (P<0.01), but there was not significant difference of prevalence of root caries between two sexes (P>0.05). Except Jilin province, there were significant differences of prevalence of crown caries between city and rural area in Liaoning and Heilongjiang provinces (P<0.01). It was no significant difference of prevalence and mean DMFT (dmft) of root caries between city and rural area in each province (P>0.05). CONCLUSION: The prevalence of dental caries of the first molar among the people in northeast China is high. The dental caries prevention and cure of first permanent molar should be emphasized in oral health field.

[Oral health survey of elder people in northeast of China].

PURPOSE: To assess the oral health status of the 65-74 years old people in the northeast of China, analyze the distribution of caries and periodontal diseases in this group of people, and provide scientific basis for establishing oral health care policies. METHODS: The representative samples were selected by multi-stage, stratified and random sampling from the three provinces of northeast of China. The diagnostic standard of dental caries and periodontal diseases were based on WHO criteria. SPSS 12.0 software package was used to analyze the data. RESULTS: Among 2364 people aged 65-74 years, the prevalence of dental caries was 67.5% and DFT was 2.68, and the data in urban was higher than in rural. The prevalence rate of periodontal disorders, such as health, gingival bleeding, dental calculus, periodontal pockets, loss of attachment was respectively 15.4%,72.0%,86.6%,58.0% and 60.1%, the prevalence rate of Heilongjiang and Liaoning province was lower than that of Jilin Province. CONCLUSIONS: Dental caries and periodontal diseases were the common diseases in northeast of China, systematic community based oral health promotion should be strengthened and preventive-oriented oral health care systems are needed in the northeast of China.

[The epidemiological investigation of dental caries among 5-year old children in Liaoning province].

PURPOSE: To investigate the oral health status and its influential factors among pre-school children in Liaoning province, and to provide first hand data for prevention of caries. METHODS: According to the Third National Oral Health Investigation criteria, the oral status of 792 children aged 5 years old in 6 regions of Liaoning province were examined. SPSS 13.0 software package was used for statistical analysis. RESULTS: The prevalence of dental caries and caries means of 792 subjects were 73.86% and 4.38 respectively. The prevalence of dental caries and caries means in rural area was significantly higher than that in city area, (X(2)=16.07,P<0.01). There was no significant difference of caries prevalence between male and female X(2)=0.46,P>0.05). The prevalence of dental caries and caries means of 5-year old children in Liaoning province were lower than that of ten years ago. CONCLUSION: Oral health status in Liaoning province should be paid more attention, and more effective measures should be taken to the incidence of dental caries.

[The prevalence and trends of caries in Liaoning province].

PURPOSE: The aim of this investigation was to analyse the dental caries prevalence, patterns and trends of all age groups in Liaoning province. METHODS: The representative samples were selected by multi-stage, stratified and random sampling, which included subjects aged 5,12,35-44 and 65-74 years. Clinical examination was based on WHO methodology(4th Ed). Student's t test and Chi-square test were applied for statistical evaluation of the mean caries experience(DMFT/dmft) and the prevalence proportion rates of dental caries (PP) between 1995 and 2005 using SPSS 12.0 software package. RESULTS: At age 5,12,35-44, the PP was 73.86%,30.05% and 63.89% respectively,which was lower than in 1995, the number being 89.49%, 59.19% and 70.26%. However, at 65-74 years, the PP was 67.40% in 2005, and there was no significant difference compared with 1995. For the two national survey, the PP and DMFT were higher in urban than in rural area. But the dmft in 5-year-old in urban was lower than in rural in 2005. CONCLUSIONS: The trend of dental caries in children and adults was declined in 2005, but it was still higher. It is essential to strengthen oral health education and promotion and continuously implement preventive oral care technique in Liaoning province.

[Effect of Chelerythrine on glucosyltransferase and water-insoluble glucan of Streptococcus mutans].

PURPOSE: To study the effect of Chelerythrine on glucosyltransferase and extra-cellular synthesis of water-insoluble glucan of Streptococcus mutans. METHODS: The Chelerythrine was used as the experimental group with concentrations ranging from 24.4microg/ml to 390.6microg/ml prepared with BHI broth medium with contained 2% glucose, and BHI culture medium was used as the control group. Streptococcus mutans was added to each group, after cultured for 24 hours in the test tubes, centrifugation was followed. The supernatants were divided into two batches. One batch of solutions was used to extract glucosyltransferase, Bradford method and Somogyi method were used to measure the content of total protein and enzyme activity, and the specific activity was calculated. Another batch of solutions was used to measure the content of water-insoluble glucan by anthrone method. The data was statistically analyzed by One-way ANOVA using SPSS13.0 software package. RESULTS: The glucosyltransferase and water-insoluble glucan of Streptococcus mutans decreased gradually with the increase of each concentration of Chelerythrine. There were highly significant differences among total sample groups, and between glucosyltransferase activity or specific activity of each experimental group and control group as well (P<0.01); Except for the group of 24.4microg/ml Chelerythrine, there were highly significant differences of water-insoluble glucan between each experimental group and control group (P<0.01).There was positive correlation between glucosyltransferase activity and water-insoluble glucan content (r=0.883, P<0.01). CONCLUSION: Chelerythrine could inhibit the glucosyltransferase and extra-cellular synthesis of water-insoluble glucan of Streptococcus mutans.

[Effect of Chelerythrine on cell surface hydrophobicity and adherence of Streptococcus mutans].

PURPOSE: To detect the effect of Chelidonium majus L. extractive Chelerythrine on the cell surface hydrophobicity and adherence of Streptococcus mutans, and to investigate the mechanism of adherence. METHODS: The Chelerythrine was doubly diluted to different concentration from 24.4 microg/ml to 781.3 microg/ml. The method of microbial adhesion to hydrophobicity(MATH) was used to measure the cell surface hydrophobicity of Streptococcus mutans; The effect of the Chelerythrine on Streptococcus mutans adhesion to glass surface was also measured. SPSS13.0 software package was used for statistical analysis, and one-way ANOVA was used to compare the difference of means among sample groups. RESULTS: The cell surface hydrophobicity of Streptococcus mutans decreased gradually with the descent of each concentration of Chelerythrine. There was significant difference between each experimental group and control group (P<0.01). There was no significant difference among groups of 195.3 microg/ml, 97.7 microg/ml, 48.8 microg/ml and 24.4 microg/ml (P>0.05). The inhibition rate of adherence increased significantly with the increase of the concentration of Chelerythrine. There was highly significant difference between group of 195.3 microg/ml or 390.6 microg/ml and control group, and the same between the two experimental groups and other experimental groups (P<0.01). CONCLUSION: There is some degree of inhibitory effect of Chelerythrine on the cell surface hydrophobicity and adherence of Streptococcus mutans. Chelerythrine possesses powerful anticariogenic potential.

[Study on tooth loss and prosthetic condition of middle-aged and elders in Liaoning province].

OBJECTIVE: To study the status of teeth loss and their restorations of the middle-aged and elders in Liaoning province. METHODS: Investigated the tooth losing and their restoration of middle-aged (35-44 years old) and elders (65-74 years old) according the method of the third national epidemiological investigation of oral health. The data was statistically analyzed by SPSS 11.0 software. RESULTS: Of all 1,584 the subjects, the sum of tooth loss were 6,776, mean tooth loss were 4.28. The rate of completion of dentition was 37.44%. There were 104 middle-aged and elders who happened deletion of dentition. There were 887 middle-aged and elders who happened defection of dentition. The tooth loss of maxillary and mandible was 3,550 and 3,226 respectively. The rate of prosthetic restoration was 52.77%. CONCLUSION: The oral health status of middle-aged and elders should be taken vey importance, especially those who lived in rural area. Dental caries and periodontal disease should be prevented so that to promote the status of middle-aged and elders oral health and to improve the quality of life.

[The prevalence of dental caries in primary dentition and the risk factors of 5-year-old children in Northeast of China].

PURPOSE: To study the prevalence of dental caries in primary dentition of 5-year-old children in Northeast of China, and assess the risk factors for dental caries. METHODS: The representative samples were selected by multi-stage, stratified and random sampling from the three provinces of Northeast of China. Dental caries of 2353 children at five-year age were recorded according to WHO criteria. The questionnaire were finished by 1191 parents of the children and analyzed with X(2) test and logistic regression using SPSS 12.0 software package. RESULTS: The prevalence of dental caries in 5-year-old children was 75.82% and dmft was 4.63. The lowest caries prevalence was noted in Heilongjiang province. The important predictors of dental caries were the educational level of parents (P<0.001) and eating sweet food before sleep (P=0.006). CONCLUSIONS: To reduce the dental caries in primary dentition, oral health education for the parents should be emphasized and sugar-intake before sleeping should be controlled.

[Experimental study of the inhibitory effects of Chelidonium majus L. extractive on Streptococcus mutans in vitro].

PURPOSE: To study the inhibitory effects of Chelidonium majus L. extractive on the growth of Streptococcus mutans in vitro, and to explore its mechanism in caries prevention. METHODS: Streptococcus mutans 25175 was chosen as the experimental bacterium. The Chelidonium majus L. extractives chelidonine and chelerythrine were double diluted to different concentrations by two-fold dilution. The inhibitory effect of Streptococcus mutans was measured by slip diffusion method. The minimal inhibitory concentration(MIC) was also determined. 0.16% liquor hibitane was used as positive control. Spearman correlation was used for statistical analysis. RESULTS: Inhibition zone of Streptococcus mutans appeared in some concentration of chelerythrine, but no inhibition zone in each concentration of chelidonine. The MIC of chelerythrine was 0.78 mg/ml which determined by liquid culture medium. The concentration of chelerythrine was highly related to the inhibitory zone of Streptococcus mutans (r=0.99, P<0.01). CONCLUSION: The antibacterial activity of Chelidonium majus L. extractive chelerythrine on Streptococcus mutans was significant,and the antibacterial activity of the concentration 100 mg/ml was higher than that of 0.16% liquor hibitane (19.4 mm), indicating that chelerythrine can be used as an agent for prevention of dental caries.

[An epidemiological investigation of deciduous dental caries among 5375 preschool children aged between 3 to 6 years in Shenyang City].

PURPOSE: To investigate the status of dental caries of deciduous teeth among preschool children in Shenyang city. METHODS: According to the criteria recommended by the World Health Organization and The Second National Oral Health Investigation, the deciduous caries of 5375 preschool children aged from 3 to 6 years were clinically examined. The mean dmft and the prevalence of dental caries for each age group were calculated. The results were analyzed using SPSS11.0 software package for t test (to compare the difference between the two sample groups), one way ANOVA (to compare the differences among three and more sample groups) and chi2 test (to compare the rate of each group). RESULTS: The prevalence of dental caries was 71.29%. The mean dmft score was 3.88. The prevalence of dental caries and mean dmft increased gradually as the children were growing up (P < 0.05).Dental caries of the upper teeth was significantly more common than that of the lower teeth (P < 0.01). Most caries were minor in degree of severity, and mostly lie in the occlusal and proximal surface. The filling rate was 10.82%.As the age increase, the filling rate increased, too. CONCLUSION: Deciduous dental caries of preschool children was an important problem in Shenyang city, and the filling rate was very low. Necessary methods for early prevention of dental caries must be taken into consideration. Supported by Scientific Research Fund for College and University from Liaoning Provincial Education Bureau (Grant No. 20201316).

[Study of caries polarization in 2-5 year-old children of Shenyang, China].

OBJECTIVE: To investigate dental caries polarization in 2-5 year-old children. METHODS: 3 799 random samples of 2-5 year-old children from attending kindergarten in Shenyang were selected. Means of dmft index and SiC index for each age group were calculated by WHO Collaborating Center. The subjects of each age group were further divided into subgroups of different level of dmft: the dmft of subgroup I was 0, the dmft of subgroup II was 1, the dmft of subgroup III was 2, the dmft of sub-group IV was equal to or more than 3. The obtained data were analyzed statistically with SPSS 10.0. RESULTS: 4.5% of 2-year-old children were carriers of 60.0% of the total dmft in that age group, 13.2% of 3-year-old children were carriers of 69.4% of the total dmft in that age group, 34.4% of 4-year-old children were carriers of 86.6% of the total dmft in that age group, and 47.8% of 5-year-old children were carriers of 89.8% of the total dmft of that age group. CONCLUSION: This study supports the assertion that a small percentage of persons with high dental caries rate and a large percentage of caries-free persons of early childhood caries.

[An analysis of the effect of adult tooth-brushing].

OBJECTIVE: This study observed plaque distribution on permanent dentition before and after brushing to analyze the effect of adult tooth-brushing. METHODS: 81 undergraduate were included in this study. Recorded the time of tooth-brushing, stained with disclosing tablets, plaque deposits on all permanent teeth were recorded using plaque index (PLI) before and after tooth-brushing. RESULTS: The time of tooth-brushing was from 28 s to 2 min 32 s, the mean time was 57 s, the males' was 49 s, the females' was 64 s. Statistically significant differences (P < 0.05) were found between males and females. The mean PLI of maxillary tooth was 0.41 +/- 0.03, for mandibular tooth was 0.47 +/- 0.03, there was significant difference between maxillary and mandibular. After brushing, the mean PLI of males was 0.532 +/- 0.04, of females was 0.295 +/- 0.03, there was significant difference of PLI between males and females (P < 0.05). These tooth PLI score were higher than other's mandibular and maxillary molars, these surface PLI score were higher than other's, buccal surface of maxillary molars and palatal site of maxillary molars. CONCLUSION: People should spend more time on brushing tooth. Tooth brushing should be emphasized on these tooth and surfaces with higher PLI score. Man should pay more attention to tooth brushing.