Smoking induced heavy metals and periodontitis: findings from the Korea National Health and Nutrition Examination Surveys 2008-2010

Association of individual and combined exposures of 10 metals with periodontitis: Results from a large population-based study

AIMS

To systematically investigate the association between individual and combined metal exposure and periodontitis.

METHODS

Data encompassing complete periodontal examinations and metal detection in blood and urine samples were procured from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. Three statistical methods, namely weighted logistic regression, Bayesian kernel machine regression (BKMR), and weighted quantile sum (WQS) regression, were used to evaluate the independent and combined associations between metals and periodontitis.

RESULTS

Elevated concentrations of blood cadmium (odds ratio [OR]: 1.73, 95% confidence interval [CI]: 1.15-2.61) and blood lead (OR: 1.17, 95 %CI: 1.02-1.34) exhibited a positive association with periodontitis, even after adjusting for potential confounding factors. The BKMR and WQS regression suggested that the co-exposure of metals was also positively associated with periodontitis. Moreover, estradiol and albumin were identified as potential mediators in the relationship between the WQS index of the 10 metals in blood and periodontitis explaining 25.36% and 2.02% of the relationship, respectively. Furthermore, generally consistent patterns of associations between metals and periodontitis and mediating roles of estrogen and albumin were observed after a series of sensitivity analyses.

CONCLUSION

This study provides evidence of positive associations between elevated levels of cadmium, lead or metal mixture and periodontitis, which may be partially mediated by sex hormones and oxidative stress indicators.

Mediating role of systemic inflammation in the association between heavy metals exposure and periodontitis risk

BACKGROUND

This study evaluated the mediating role of systemic inflammation in the association between exposure to heavy metals and periodontitis in a nationwide sample of adults.

METHODS

Pooled cross-sectional data from the National Health and Nutrition Examination Survey (NHANES 2009-2014) were used (n = 8993). Periodontitis was defined by a full-mouth examination and classified as no/mild and moderate/severe (mod/sev) groups. Blood and urinary heavy metal levels were investigated, including cadmium (Cd), lead (Pb), and mercury (Hg). In addition, systemic inflammation was assessed using circulatory leukocyte counts and C-reactive protein (CRP) levels.

RESULTS

Multivariable logistic regression analysis revealed the positive associations of blood and urinary levels of Cd and Pb with mod/sev periodontitis. In contrast,blood Hg levels did not show a significant association. The odds of having periodontitis were 1.233 and 1.311 times higher for each one-unit increment in Ln-transformed blood Cd (95% confidence interval [CI]: 1.109-1.371) and Pb (95% CI: 1.170-1.470), respectively. Mediation analysis suggested a 6.3% to 11.5% contribution of leucocyte counts in the association of blood Cd and Pb levels with periodontitis. Sensitivity analyses for urinary Cd levels yielded consistent mediating effects. However, no significant mediating effect of CRP was detected.

CONCLUSION

Higher exposures to Cd and Pb were positively associated with periodontitis risk. These associations might be partially mediated by the elevated levels of leukocytes rather than CRP. Further longitudinal studies are needed to elucidate the discordant results of the systemic inflammatory biomarkers.

Association between polycyclic aromatic hydrocarbons and periodontitis: Results from a large population-based study

AIM

To explore the association between polycyclic aromatic hydrocarbons (PAHs) (measured using urinary metabolites) and periodontitis using data from the National Health and Nutrition Examination Survey 2009-2014.

MATERIALS AND METHODS

Weighted binary logistic regression, Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regression were used to evaluate independent and joint associations between the six urinary monohydroxylated metabolites of PAHs (OH-PAHs) and periodontitis.

RESULTS

In all, 3413 participants were included in this study. All six urinary OH-PAHs were present at higher levels in the periodontitis group compared with the non-periodontitis group (p < .001). Fully adjusted multivariable logistic regressions showed positive associations between the six urinary OH-PAHs and periodontitis (p < .05). Higher concentrations of OH-PAHs were also positively associated with attachment loss, periodontal pocket depth (PPD) and the number of tooth loss. BKMR and WQS regression yielded similar positive associations between OH-PAH mixtures and periodontitis.

CONCLUSIONS

PAHs and their mixture are positively associated with periodontitis, which may provide novel insights into periodontitis prevention from an environmental exposure perspective.

Association between periodontal disease and hypertriglyceridemia: Propensity score matching analysis using the 7th Korea National Health and Nutrition Examination Survey

The prevalence of periodontitis and dyslipidemia continues to increase, and several studies have reported an association between the 2. Therefore, we assessed the relationship between periodontitis and hypertriglyceridemia using propensity score matching to efficiently address confounding factors, as well as complex sample analysis with data from Korea National Health and Nutrition Examination Survey VII (2016-2018). To match the 1:1 ratio between the groups with and without periodontitis, the propensity scores of covariates, such as age, sex, education, income, smoking, drinking, obesity, and diabetes mellitus, were calculated using logistic regression. Both results of logistic regression analysis using complex sample design for whole and matched sample after propensity score matching demonstrated a significant association between hypertriglyceridemia and periodontitis, of which the adjusted odds ratio was 1.28 (95% confidence interval = 1.10-1.50) and 1.29 (95% confidence interval = 1.09-1.52), respectively. Our findings suggest that dental healthcare workers can help raise awareness among patients with periodontitis regarding the association between periodontitis and hypertriglyceridemia, which may help them manage the condition and receive treatment.

Association of urinary heavy metal combined exposure with periodontitis among US adults from NHANES 2011-2014

Some heavy metals are associated with periodontitis; whereas most of these associations have focused on individual metal, there are no specific studies on the effects of combined heavy metal exposure on periodontitis. We conducted an analysis on the association between urinary heavy metal exposure and periodontitis in participants aged 30 years and older using multiple logistic regression and Bayesian kernel machine regression (BKMR). This analysis was performed on data from the National Health and Nutrition Examination Survey from 2011 to 2014. The study found that using logistic regression, the 4th quartile of urinary lead and molybdenum and the 3rd quartile of urinary strontium were positively associated with periodontitis compared to the reference quartile after adjusting for covariates. Odds ratio (OR) with 95% confidence interval (CI) was 1.738 (1.069-2.826), 1.515 (1.025-2.239), and 1.498 (1.010-2.222), respectively. The 3rd and 4th quartiles of urinary cobalt were negatively associated with periodontitis, and their ORs and 95% CIs were 0.639 (0.438-0.934) and 0.571 (0.377-0.964), respectively. The BKMR model showed that urinary barium, lead, and molybdenum were positively associated with periodontitis in a range of concentrations and urinary cobalt, manganese, tin, and strontium were negatively correlated with periodontitis. Furthermore, the overall association between urinary heavy metals and periodontitis was positive. Our study provides evidence for an association between exposure to multiple urinary heavy metals and periodontitis. However, further longitudinal studies are needed to explore the specific mechanisms involved.

Heavy metals in drinking water and periodontitis: evidence from the national oral health survey from China

BACKGROUND

Periodontitis has become an increasingly important public health issue, coupled with a high economic burden for prevention and treatment. Exposure to essential trace heavy metals has been associated with various diseases; however, the relationships between essential trace heavy metals and periodontitis remain inconclusive.

OBJECTIVES

To investigate the association between essential trace heavy metals in tap water and periodontitis in a nationally representative sample in China.

METHODS

We conducted a nationwide study including 1348 participants from the Fourth National Oral Health Survey in the 2015-2016 period. The trace heavy metals concentration was measured in the local pipeline terminal tap water. Periodontitis was diagnosed according to the classification scheme proposed at the 2018 world workshop on the classification of periodontal and peri-implant diseases and conditions. We used weighted multivariable logistic regression to estimate the association between essential trace heavy metals and the risk of periodontitis. We additionally used spline analysis to explore the possible nonlinear dose-response associations.

RESULTS

Periodontitis patients were exposed to higher concentrations of essential trace heavy metals. In adjusted models, for 1 SD increase in the concentration of iron, manganese, and copper in tap water, the risk of periodontitis increased by 30% (OR: 1.30, 95%CI: 1.12-1.50), 20% (OR: 1.20, 95%CI: 1.03-1.41), and 20% (OR: 1.20, 95%CI: 1.04-1.39), respectively. Stratified analyses demonstrated that the associations between essential trace heavy metals and periodontitis were higher in females, elders, and rural residents. Spline analysis revealed nonlinear exposure-response relationships between periodontitis and exposure to iron, manganese, and copper in tap water.

CONCLUSIONS

Exposures to essential trace heavy metals in drinking water were associated with greater odds of periodontitis. Given the growing burden of periodontitis, our study sheds light on tailored public health policies for improving drinking water standards to alleviate periodontitis impairment.

The Beneficial Impact of the Black Chokeberry Extract against the Oxidative Stress in the Sublingual Salivary Gland of Rats Intoxicated with Cadmium

Cadmium (Cd) is one of the most harmful xenobiotics to which humans are exposed, mainly by the oral route, throughout life. Preventive strategies are searched as low intoxication with this element, among others due to its prooxidative properties, can be deleterious to health and the exposure to it is continuously increasing. Recently, interest has been paid to plant raw materials with a high antioxidative potential to oppose the prooxidative properties of cadmium, such as black chokeberry (Aronia melanocarpa L. fruit), which is rich in polyphenolic compounds. The study was aimed at assessing whether the chokeberry extract may counteract the prooxidative impact of low-level and moderate repeated intoxication with cadmium on the sublingual salivary gland. The investigation was performed on 96 Wistar rats (females), which were treated with a 0.1% aqueous extract from chokeberries or/and a diet containing 1 or 5 mg Cd/kg for 3 and 10 months, and control animals. The intoxication with cadmium, in a dose- and time-dependent manner, attenuated the enzymatic and nonenzymatic antioxidative potential and increased the concentration of hydrogen peroxide and total oxidative status of the sublingual salivary gland resulting in an occurrence of oxidative stress, enhancement of lipid peroxidation, and oxidative injuries of proteins in this salivary gland. The treatment with the black chokeberry extract during the intoxication with cadmium prevented this xenobiotic-caused oxidative/reductive imbalance and oxidative modifications of proteins and lipids in the salivary gland. The above results allow the conclusion that the consumption of black chokeberry products during intoxication with cadmium can prevent oxidative stress and its consequences in the sublingual salivary gland and thus counteract the unfavourable impact of this xenobiotic on the oral cavity.

Occurrence of neonicotinoid insecticides and their metabolites in tooth samples collected from south China: Associations with periodontitis

Neonicotinoid insecticides (NEOs) are widely used in agricultural production processes in China and worldwide. NEOs have been an increasing concern because of their potential toxicity to nontarget organisms. However, studies that focused on human exposure to NEOs in China are limited. In this study, levels of six parent NEOs (p-NEOs), namely imidacloprid (IMI), acetamiprid (ACE), clothianidin (CLO), dinotefuran (DIN), thiamethoxam (THIX), and thiacloprid (THI), and three metabolites (m-NEOs), such as 5-hydroxy-imidacloprid (5-OH-IMI), 1-methyl-3-(tetrahydro-3-furyl methyl) urea (UF), and N-desmethyl-acetamiprid (N-dm-ACE) were measured in 127 tooth samples collected from South China. P-NEOs and m-NEOs are frequently detected (76%-93%) in tooth samples, with median levels of 0.03-1.20 ng/g. UF is the most abundant NEOs in tooth samples (36%). Females have higher NEO levels than males, and gender-related differences in NEO levels are found. Associations among most p-NEOs are also found (p < 0.05), indicating the source of human exposure to p-NEOs is related. However, no significant relationships (p > 0.05) between levels of m-NEOs and their corresponding p-NEOs are found, suggesting that exogenous m-NEOs contribute to exposure. We have also examined the associations between human NEOs exposure and periodontitis, and associations between NEO exposure and periodontitis are observed (OR = 2.63-7.33; 95% CI = 1.01-21.1, p-trend < 0.05). Our results suggest that NEO levels are associated with increased odds of prevalent periodontitis. This study is the first to report about p-NEOs and m-NEOs in tooth samples collected from South China.

Metallic elements in human hair from residents in smelting districts in northeast China: Environmental factors and differences in ingestion media

The health of residents in Huludao City is affected by the emissions of heavy metals from smelting, diet and atmospheric precipitation. This study investigated the concentrations of Hg, Cd, Pb, Cu and Zn in scalp hair samples from 259 residents of different ages and genders from five districts in Huludao City and examined the main factors for heavy metal exposure. Cd and Pb concentrations in hair samples exceeded the normal concentration ranges for human hair (Cd < 0.3 mg/kg; Pb < 9.3 mg/kg), and the highest Pb concentrations were found in subjects in the age range 0-15 years. Samples from men were higher in Cd and Pb compared to those for women. Workers from the Huludao zinc plant (HZP) had higher concentrations of all metals in their hair relative to other occupations except for Cu. Geographically, the highest Cd and Pb concentrations in hair were found for residents living in Daochi district (DCD) and the Zn plant district (ZPD), respectively. In smelting regions, the effects of dust ingestion on heavy metal exposure were more important than in non-smelting regions.

Exposure to occupational noise and periodontitis in Korean workers

BACKGROUND

Chronic exposure to occupational noise is reported to cause a wide range of health problems. But, there are no reports on studies investigating the association between noise exposure and periodontitis. The purpose of this study was to examine the relationship between occupational noise exposure and periodontitis in a nationally representative sample of Korean workers.

METHODS

This cross-sectional study used data from the 4^th Korean National Health and Nutrition Examination Survey. The study sample included 8,927 workers aged 19 to 54 years. Noise exposure assessment was performed by using self-report questionnaires. The dependent variable was periodontitis. Age, sex, perceived stress level, place of residence, income, education, health behaviors (frequency of daily toothbrushing, binge drinking, smoking status, regular dental checkup), diabetes, obesity, and white blood cell count were included as covariates. Logistic regression analyses estimated the association between noise exposure and periodontitis after sequential adjustment.

RESULTS

Compared with never-exposed individuals, participants exposed to occupational noise had an increased prevalence of periodontitis. The association remained significant after full adjustment of covariates (odds ratio [OR] 1.34; 95% confidence interval [CI] 1.06 to 1.70). Association of noise exposure with periodontitis was particularly strong for individuals aged < 45 years (OR 1.65; 95% CI 1.22 to 2.23).

CONCLUSIONS

Our study shows that there is an association between occupational noise exposure and periodontitis in a representative sample of Korean workers. Policy efforts to improve workplace noise environments might have an effect on improving periodontal health status among Korean workers.

The Protective Impact of Black Chokeberry Fruit Extract (Aronia melanocarpa L.) on the Oxidoreductive System of the Parotid Gland of Rats Exposed to Cadmium

Cadmium (Cd) is a strongly toxic heavy metal with prooxidative properties. Since the exposure of the general population to this metal is predicted to increase, effective methods are being sought to prevent its negative actions. One of them involves the use of the antioxidant potential of polyphenol compounds contained in black chokeberry fruit extract and their capability of complex formation with Cd2+. The study objective was to investigate whether the administration of A. melanocarpa fruit extract rich in polyphenol compounds during low and moderate exposures to cadmium can protect the parotid gland against oxidative damage. The study was conducted using the experimental model on female Wistar rats which were given 0.1% aqueous extract of Aronia melanocarpa fruit (AE) and/or cadmium at a concentration of 1 (Cd1) or 5 (Cd5) mg Cd/kg feed for 3 and 10 months, and on control animals. The exposure to Cd attenuated the enzymatic antioxidant barrier (catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx)) and increased the concentration of hydrogen peroxide (H2O2), protein carbonyl (PC) groups, and oxidized lipids (LPO) in parotid gland. These disorders led to a reduction in the total antioxidative status (TAS), an increase in the total oxidative state (TOS), and development of stress. The administration of AE at both levels of exposure to cadmium substantially improved the enzymatic antioxidant barrier (CAT, SOD, GPx) and prevented oxidative damage to cellular macromolecules (PC, LPO) and the increase in the level of H2O2, MPO, TOS, and stress indicator (OSI = TOS/TAS) in the parotid gland. Concluding, it should be stated that the consumption of aronia products may prevent oxidative/antioxidative imbalance induced by Cd and oxidative stress development in the parotid gland, thus protecting the gland from damage.

Association of Periodontitis with the Concentration Levels of Germanium and Tin in Hair

The purpose of this study was to investigate whether or not the concentration levels of certain kinds of trace elements in hair are associated with periodontitis. We studied a total of 109 participants, which are composed of 25 participants with periodontitis and 84 participants without periodontitis. Periodontal conditions were assessed by measuring the periodontal clinical attachment loss and pocket depth, which were determined at six sites of all teeth. Periodontitis was defined according to the criteria of periodontitis proposed by CDC-AAP. The hair samples were washed with acetone, water, and extran (1%v/v), and then aliquots of hair samples were wet-ashed. This sample solution was analyzed by Perkin-Elmer Mass Spectrometer. The odds ratios and 95% confidence intervals of the concentration levels of trace elements for periodontitis were calculated by multivariate logistic regression analysis. After adjusting all confounders, it was found that the higher concentration level of germanium in hair was significantly and positively associated with periodontitis (odds ratio [OR] 7.12; 95% confidential interval [CI] 2.03-25.00). The higher concentration level of tin in hair was significantly and negatively associated with periodontitis (OR 0.27; 95% CI 0.08-0.94). It was concluded that there was a significant relationship between periodontitis and the concentration level of germanium and tin in hair.

Environmental lead effects on gene expression in oral epithelial cells

BACKGROUND AND OBJECTIVE

Host responses in periodontitis span a range of local and emigrating cell types and biomolecules. Accumulating evidence regarding the expression of this disease across the population suggests some component of genetic variation that controls onset and severity of disease, in concert with the qualitative and quantitative parameters of the oral microbiome at sites of disease. However, there remains little information regarding the capacity of accruing environmental stressors or modifiers over a lifespan at both the host genetic and microbial ecology levels to understand fully the population variation in disease. This study evaluated the impact of environmental lead exposure on the responses of oral epithelial cells to challenge with a model pathogenic oral biofilm.

METHODS AND RESULTS

Using NanoString technology to quantify gene expression profiles of an array of 511 host response-associated genes in the epithelial cells, we identified an interesting primary panel of basal responses of the cells with numerous genes not previously considered as major response markers for epithelial cells, eg, interleukin (IL)-32, CTNNB1, CD59, MIF, CD44 and CD99. Even high levels of environment lead had little effect on these constitutive responses. Challenge of the cells with the biofilms (Streptococcus gordonii/Fusobacterium nucleatum/Porphyromonas gingivalis) resulted in significant increases in an array of host immune-related genes (134 of 511). The greatest magnitude in differential expression was observed with many genes not previously described as major response genes in epithelial cells, including IL-32, CD44, NFKBIA, CTSC, TNFAIP3, IL-1A, IL-1B, IL-8 and CCL20. The effects of environmental lead on responses to the biofilms were mixed, although levels of IL-8, CCL20 and CD70 were significantly decreased at lead concentrations of 1 and/or 5 μmol/L.

CONCLUSION

The results provided new information on a portfolio of genes expressed by oral epithelial cells, targeted substantial increases in an array of immune-related genes post-biofilm challenge, and a focused impact of environmental lead on these induced responses.

Protective Effect of Increased Zinc Supply against Oxidative Damage of Sublingual Gland in Chronic Exposure to Cadmium: Experimental Study on Rats

Cadmium is one of the main chemical pollutants found in the daily environment of developed countries. Cigarettes are a significant source of that metal, which makes it important in terms of oral cavity health. The aim of this study was to determine if increased supply of zinc in chronic exposure to cadmium might protect the sublingual gland structure against oxidative damage. The experiment took 12 months and was conducted on 72 adult male rats. They were randomized into 9 groups. Eight groups received cadmium in drinking water (as CdCl₂) at 5 or 50 mg Cd/dm³ and/or zinc (as ZnCl₂) at 30 or 60 mg Zn/dm³. The control group received regular water. In the sublingual gland of all animal groups, levels of oxidative parameters were measured. The oxidative stress index was calculated as a TOS/TAS ratio. Cadmium exposure at 5 mg and 50 mg Cd/dm³ induced oxidative stress in the sublingual glands of the rats. Cadmium reduced the TAS and GSH levels and increased LPO, H₂O₂, TOS, and OSI. In cadmium exposure conditions, increasing the supply of zinc by 79% or 151%, as compared to the standard dietary intake of this microelement, completely prevented the reduction of TAS and GSH levels and accumulation of LPO, H₂O₂, and TOS in the examined gland at both exposure levels to that metal. The outcome data confirm the protective effect of increased zinc intake on the sublingual gland tissue in chronic cadmium exposure.

Cadmium Exposure Disrupts Periodontal Bone in Experimental Animals: Implications for Periodontal Disease in Humans

Cadmium (Cd) is an environmental contaminant that damages the kidney, the liver, and bones. Some epidemiological studies showed associations between Cd exposure and periodontal disease. The purpose of this study was to examine the relationship between Cd exposure and periodontal disease in experimental animals. Male Sprague/Dawley rats were given daily subcutaneous injections of Cd (0.6 mg/kg/day) for up to 12 weeks. The animals were euthanized, and their mandibles and maxillae were evaluated for levels of periodontal bone by measuring the distance from the cementoenamel junction (CEJ) to the alveolar bone crest (ABC) of the molar roots. After 12 weeks of Cd exposure in animals, there was a significantly greater distance between the CEJ and ABC in the palatal aspect of the maxillary molars and the lingual aspect of the mandibular molars when compared with controls (p < 0.0001). This study shows that Cd has significant, time-dependent effects on periodontal bone in an animal model of Cd exposure. These findings support the possibility of Cd being a contributing factor to the development of periodontal disease in humans.

The association between periodontitis and sleep duration

AIM

Due to its potential to influence systemic inflammation and oxidative stress, and to predispose to bacterial infections, sleep duration could potentially be a risk factor for periodontitis. The aim of this cross-sectional study was to evaluate if there was in 2012 an association between periodontitis and sleep duration in a representative sample of the South Korean population.

MATERIALS AND METHODS

A total of 5812 subjects representative of 39.4 million of adults were examined. Multivariate logistic regressions were applied controlling for age, gender, education, smoking status, alcoholism and consumption frequency of coffee, tea, chocolate and red wine.

RESULTS

Compared to the group sleeping ≤5 h/day, the adjusted odds ratios for periodontitis prevalence defined as Community Periodontal Index (CPI) = 4 were OR = 2.46 (95% CI: 1.20-5.06) in the 6 h/day sleepers group, OR = 2.66 (95% CI: 1.35-5.25) in the 7 h/day sleepers group, OR = 2.29 (95% CI: 1.13-4.63) in the 8 h/day sleepers group and OR = 4.27 (95% CI: 1.83-9.97) in the ≥9 h/day sleepers group. The association has shown to be highlighted in middle-aged people, females, non-smokers, lower educated, with lower lead and higher cadmium blood levels and with higher carotene dietary intake ones and to be partially mediated by lipid profile alterations, diabetes, serum Vitamin D levels and WBC count.

CONCLUSIONS

A novel, direct and independent association between sleep duration and the prevalence of periodontitis was found. However, it needs to be investigated how the factors influencing the sleep duration affect this association.

Detoxification effects of phytonutrients against environmental toxicants and sharing of clinical experience on practical applications

According to the Food and Health Bureau and Trade and Industry Department of the Hong Kong Government, 90 % of the total food supply in Hong Kong was imported from the Mainland China. In addition, the hidden or illegal use of prohibited pesticides, food adulteration (e.g., using industrial salt in food processing, using gutter oil as cooking oil), and pollutions were periodically reported by the media. Excessive exposure to toxic heavy metals or persistent organic pollutants (POPs) from diet or environmental is inevitable amid industrialization and pollution. Understanding of the detoxification ability among nutrients in plant-based food (i.e., phytonutrients in green tea, onion, garlic, coriander, and turmeric) offers therapeutic and preventive effects against the poisoning effects due to these pollutants. Oxidative stress and pro-inflammatory actions are the common mechanisms for heavy metals or POPs toxicities, while phytonutrients counteracts these cellular insults by anti-oxidation, upregulation of anti-inflammatory pathways, and chelation.

Geographic information system analysis on the distribution of patients visiting the periodontology department at a dental college hospital

PURPOSE

The aim of this study is to analyze and visualize the distribution of patients visiting the periodontology department at a dental college hospital, using a geographic information system (GIS) to utilize these data in patient care and treatment planning, which may help to assess the risk and prevent periodontal diseases.

METHODS

Basic patient information data were obtained from Dankook University Dental Hospital, including the unit number, gender, date of birth, and address, down to the dong (neighborhood) administrative district unit, of 306,656 patients who visited the hospital between 2007 and 2014. The data of only 26,457 patients who visited the periodontology department were included in this analysis. The patient distribution was visualized using GIS. Statistical analyses including multiple regression, logistic regression, and geographically weighted regression were performed using SAS 9.3 and ArcGIS 10.1. Five factors, namely proximity, accessibility, age, gender, and socioeconomic status, were investigated as the explanatory variables of the patient distribution.

RESULTS

The visualized patient data showed a nationwide scale of the patient distribution. The mean distance from each patient's regional center to the hospital was 30.94±29.62 km and was inversely proportional to the number of patients from the respective regions. The distance from a regional center to the adjacent toll gate had various effects depending on the local distance from the hospital. The average age of the patients was 52.41±12.97 years. Further, a majority of regions showed a male dominance. Personal income had inconsistent results between analyses.

CONCLUSIONS

The distribution of patients is significantly affected by the proximity, accessibility, age, gender and socioeconomic status of patients, and the patients visiting the periodontology department travelled farther distances than those visiting the other departments. The underlying reason for this needs to be analyzed further.