Schisandrae Fructus ethanol extract attenuates particulate matter 2.5-induced inflammatory and oxidative responses by blocking the activation of the ROS-dependent NFκB signaling pathway

BACKGROUND/OBJECTIVES@#Schisandrae Fructus, the fruit of Schisandra chinensis Baill., has traditionally been used as a medicinal herb for the treatment of various diseases, and has proven its various pharmacological effects, including anti-inflammatory and antioxidant activities. In this study, we investigated the inhibitory effect of Schisandrae Fructus ethanol extract (SF) on inflammatory and oxidative stress in particulate matter 2.5 (PM2.5)-treated RAW 264.7 macrophages.MATERIALS/METHODS: To investigate the anti-inflammatory and antioxidant effects of SF in PM2.5-stimulated RAW 264.7 cells, the levels of pro-inflammatory mediator such as nitric oxide (NO) and prostaglandin E2 (PGE2 ), cytokines including interleukin (IL)-6 and IL-1β, and reactive oxygen species (ROS) were measured. To elucidate the mechanism underlying the effect of SF, the expression of genes involved in the generation of inflammatory factors was also investigated. We further evaluated the anti-inflammatory and antioxidant efficacy of SF against PM2.5 in the zebrafish model. @*RESULTS@#The results indicated that SF treatment significantly inhibited the PM2.5-induced release of NO and PGE2 , which was associated with decreased inducible NO synthase and cyclooxygenase-2 expression. SF also attenuated the PM2.5-induced expression of IL-6 and IL-1β, reducing their extracellular secretion. Moreover, SF suppressed the PM2.5-mediated translocation of nuclear factor-kappa B (NF-κB) from the cytosol into nuclei and the degradation of inhibitor IκB-α, indicating that SF exhibited anti-inflammatory effects by inhibiting the NF-κB signaling pathway. In addition, SF abolished PM2.5-induced generation of ROS, similar to the pretreatment of a ROS scavenger, but not by an inhibitor of NF-κB activity. Furthermore, SF showed strong protective effects against NO and ROS production in PM2.5-treated zebrafish larvae. @*CONCLUSIONS@#Our findings suggest that SF exerts anti-inflammatory and antioxidant effects against PM2.5 through ROS-dependent down-regulating the NF-κB signaling pathway, and that SF can be a potential functional substance to prevent PM2.5-mediated inflammatory and oxidative damage.

Association between masticatory muscle activity and oral conditions in young female college students / 대한해부학회지

The purpose of this study was to determine the characteristics of masticatory muscle activity and various oral condition factors, and to analyze their associations in order to improve the prevention and diagnosis of masticatory musclerelated diseases. This study included 30 Korean females (mean age of 20 years, age range of 19–21 years). Participants were instructed to complete a self-written questionnaire on factors that may affect their muscle activity. Surface electromyography was used to measure the activity of the masseter and temporalis muscles. We also observed the buccal mucosa ridge, tongue indentation, tooth cracks and fractures, and mandibular tori in the oral cavity. Spearman correlation analysis and the nonparametric Mann–Whitney U test were applied to the data. When subjects had temporomandibular disorder, the right temporalis muscle exhibited significantly lower activity (P<0.05). Those who had received orthodontic treatment within the previous 2 years showed significantly lower activity of the left masseter muscle (P<0.05). Those who had a left buccal mucosa ridge exhibited lower activity of the left masseter muscle and higher activity of the right temporalis muscle compared with those without such a ridge (P<0.05). Participants with no tongue indentation showed significantly higher activity in the left masseter muscle (P<0.05). These results indicate that there are relationships between masticatory muscle activity and various factors related to the oral condition.

Succinate-treated macrophages attenuate dextran sodium sulfate colitis in mice

The safety and effectiveness of adalimumab was demonstrated in a phase 3 trial in Japanese patients with intestinal Behçet’s disease. The aim of this study was to evaluate the long-term safety and effectiveness of adalimumab in Japanese patients with intestinal Behçet’s disease.

Cumulative Exposure to Metabolic Syndrome Components and the Risk of Dementia: A Nationwide Population-Based Study

Background@#Metabolic disturbances are modifiable risk factors for dementia. Because the status of metabolic syndrome (MetS) and its components changes over time, we aimed to investigate the association of the cumulative exposure to MetS and its components with the risk of dementia. @*Methods@#Adults (n=1,492,776; ≥45-years-old) who received health examinations for 4 consecutive years were identified from a nationwide population-based cohort in Korea. Two exposure-weighted scores were calculated: cumulative number of MetS diagnoses (MetS exposure score, range of 0 to 4) and the composite of its five components (MetS component exposure score, range of 0 to 20). Hazard ratio (HR) and 95% confidence interval (CI) values for dementia were analyzed using the multivariable Cox proportional-hazards model. @*Results@#Overall, 47.1% of subjects were diagnosed with MetS at least once, and 11.5% had persistent MetS. During the mean 5.2 years of follow-up, there were 7,341 cases (0.5%) of incident dementia. There was a stepwise increase in the risk of all-cause dementia, Alzheimer’s disease, and vascular dementia with increasing MetS exposure score and MetS component exposure score (each P for trend <0.0001). The HR of all-cause dementia was 2.62 (95% CI, 1.87 to 3.68) in subjects with a MetS component exposure score of 20 compared with those with a score of 0. People fulfilling only one MetS component out of 20 already had an approximately 40% increased risk of all-cause dementia and Alzheimer’s disease. @*Conclusion@#More cumulative exposure to metabolic disturbances was associated with a higher risk of dementia. Of note, even minimal exposure to MetS components had a significant effect on the risk of dementia.

Succinate-treated macrophages attenuate dextran sodium sulfate colitis in mice

The safety and effectiveness of adalimumab was demonstrated in a phase 3 trial in Japanese patients with intestinal Behçet’s disease. The aim of this study was to evaluate the long-term safety and effectiveness of adalimumab in Japanese patients with intestinal Behçet’s disease.

Cumulative Exposure to Metabolic Syndrome Components and the Risk of Dementia: A Nationwide Population-Based Study

Background@#Metabolic disturbances are modifiable risk factors for dementia. Because the status of metabolic syndrome (MetS) and its components changes over time, we aimed to investigate the association of the cumulative exposure to MetS and its components with the risk of dementia. @*Methods@#Adults (n=1,492,776; ≥45-years-old) who received health examinations for 4 consecutive years were identified from a nationwide population-based cohort in Korea. Two exposure-weighted scores were calculated: cumulative number of MetS diagnoses (MetS exposure score, range of 0 to 4) and the composite of its five components (MetS component exposure score, range of 0 to 20). Hazard ratio (HR) and 95% confidence interval (CI) values for dementia were analyzed using the multivariable Cox proportional-hazards model. @*Results@#Overall, 47.1% of subjects were diagnosed with MetS at least once, and 11.5% had persistent MetS. During the mean 5.2 years of follow-up, there were 7,341 cases (0.5%) of incident dementia. There was a stepwise increase in the risk of all-cause dementia, Alzheimer’s disease, and vascular dementia with increasing MetS exposure score and MetS component exposure score (each P for trend <0.0001). The HR of all-cause dementia was 2.62 (95% CI, 1.87 to 3.68) in subjects with a MetS component exposure score of 20 compared with those with a score of 0. People fulfilling only one MetS component out of 20 already had an approximately 40% increased risk of all-cause dementia and Alzheimer’s disease. @*Conclusion@#More cumulative exposure to metabolic disturbances was associated with a higher risk of dementia. Of note, even minimal exposure to MetS components had a significant effect on the risk of dementia.

Quantitative Proteomic Analysis of the Expression of SARS-CoV-2 Receptors in the Gut of Patients with Chronic Enterocolitis

The cellular entry of severe respiratory syndrome coronavirus-2 (SARS-CoV-2) is mediated by interaction with the human angiotensin-converting enzyme 2 (ACE2), a receptor that is expressed on both lung and intestinal epithelial cells. We performed a quantitative proteomic analysis to investigate the expression of possible receptors for SARS-CoV-2 in the intestinal mucosa of 23 patients with chronic colitis. ACE2 expression was low and remained unaltered in the gut of patients with ulcerative colitis (UC), Crohn’s disease (CD), intestinal Behćet’s disease (BD), and intestinal tuberculosis (TB), when compared with that of healthy individuals. Additionally, the expression levels of some probable co-receptors, including dipeptidyl peptidase 4 (DPP4), aminopeptidase N (AMPN), and glutamyl aminopeptidase (AMPE), were unchanged in the affected UC, CD, intestinal BD, and intestinal TB colon mucosa samples. In conclusion, gut inflammation associated with chronic colitis does not mediate a further increase in the cellular entry of SARS-CoV-2.

Variabilities in Weight and Waist Circumference and Risk of Myocardial Infarction, Stroke, and Mortality: A Nationwide Cohort Study

Background@#Evidence regarding the association between variabilities in obesity measures and health outcomes is limited. We aimed to examine the association between variabilities in obesity measures and cardiovascular outcomes and all-cause mortality. @*Methods@#We identified 4,244,460 individuals who underwent health examination conducted by the Korean National Health Insurance Service during 2012, with ≥3 anthropometric measurements between 2009 and 2012. Variabilities in body weight (BW) and waist circumference (WC) were assessed using four indices including variability independent of the mean (VIM). We performed multivariable Cox proportional hazards regression analyses. @*Results@#During follow-up of 4.4 years, 16,095, 18,957, and 30,200 cases of myocardial infarction (MI), stroke, and all-cause mortality were recorded. Compared to individuals with the lowest quartiles, incrementally higher risks of study outcomes and those of stroke and all-cause mortality were observed among individuals in higher quartiles of VIM for BW and VIM for WC, respectively. The multivariable adjusted hazard ratios and 95% confidence intervals comparing the highest versus lowest quartile groups of VIM for BW were 1.17 (1.12 to 1.22) for MI, 1.20 (1.16 to 1.25) for stroke, and 1.66 (1.60 to 1.71) for all-cause mortality; 1.07 (1.03 to 1.12) for stroke and 1.29 (1.25 to 1.33) for all-cause mortality regarding VIM for WC. These associations were similar with respect to the other indices for variability. @*Conclusion@#This study revealed positive associations between variabilities in BW and WC and cardiovascular outcomes and allcause mortality. Our findings suggest that variabilities in obesity measures are associated with adverse health outcomes in the general population.

Cross-Correlation Analysis of the Incidence of Multidrug-Resistant Organisms with Hand Hygiene Compliance and Effectiveness of Alcohol-Gel Hand Hygiene Practice / 대한임상미생물학회지

Background@#Multidrug- resistant organisms (MDRO) are a serious concern in healthcareassociated infections. Hand hygiene (HH) is essential to prevent the spread of MDRO in the healthcare institutes. The aim of this study was to investigate the relationship between the incidence of MDRO and hand hygiene compliance and the experimental effectiveness of alcohol-gel hand hygiene practice. @*Methods@#From March 2016 to September 2018, we analyzed the cross-correlation between the incidence of MDRO and the HH compliance each month at Gyeongsang National University Changwon Hospital. We employed an experiment to observe the effect of alcohol gel hand hygiene practice on the reduction of organisms on the hand surface using the handagar plates. @*Results@#Among the MDRO, only vancomycin-resistant enterococci (VRE) showed a moderate correlation with the HH rate (r = 0.55). The hand-agar plate experiment showed a significant bacterial reduction for inadequate HH (mean 3.47 CFU) and optimal HH (mean, 0.84 CFU) than before HH (mean, 11.56 CFU) (n = 32, P = 0.006). @*Conclusion@#The incidence of VRE showed a moderate correlation with HH among MDRO in the longitudinal analysis. HH practice was more effective in preventing the spread of VRE compared with other MDRO in our institute. Optimal alcohol-gel HH practice can effectively remove bacteria on the hand surface.

Variabilities in Weight and Waist Circumference and Risk of Myocardial Infarction, Stroke, and Mortality: A Nationwide Cohort Study

Background@#Evidence regarding the association between variabilities in obesity measures and health outcomes is limited. We aimed to examine the association between variabilities in obesity measures and cardiovascular outcomes and all-cause mortality. @*Methods@#We identified 4,244,460 individuals who underwent health examination conducted by the Korean National Health Insurance Service during 2012, with ≥3 anthropometric measurements between 2009 and 2012. Variabilities in body weight (BW) and waist circumference (WC) were assessed using four indices including variability independent of the mean (VIM). We performed multivariable Cox proportional hazards regression analyses. @*Results@#During follow-up of 4.4 years, 16,095, 18,957, and 30,200 cases of myocardial infarction (MI), stroke, and all-cause mortality were recorded. Compared to individuals with the lowest quartiles, incrementally higher risks of study outcomes and those of stroke and all-cause mortality were observed among individuals in higher quartiles of VIM for BW and VIM for WC, respectively. The multivariable adjusted hazard ratios and 95% confidence intervals comparing the highest versus lowest quartile groups of VIM for BW were 1.17 (1.12 to 1.22) for MI, 1.20 (1.16 to 1.25) for stroke, and 1.66 (1.60 to 1.71) for all-cause mortality; 1.07 (1.03 to 1.12) for stroke and 1.29 (1.25 to 1.33) for all-cause mortality regarding VIM for WC. These associations were similar with respect to the other indices for variability. @*Conclusion@#This study revealed positive associations between variabilities in BW and WC and cardiovascular outcomes and allcause mortality. Our findings suggest that variabilities in obesity measures are associated with adverse health outcomes in the general population.

Cross-Correlation Analysis of the Incidence of Multidrug-Resistant Organisms with Hand Hygiene Compliance and Effectiveness of Alcohol-Gel Hand Hygiene Practice / 대한임상미생물학회지

Background@#Multidrug- resistant organisms (MDRO) are a serious concern in healthcareassociated infections. Hand hygiene (HH) is essential to prevent the spread of MDRO in the healthcare institutes. The aim of this study was to investigate the relationship between the incidence of MDRO and hand hygiene compliance and the experimental effectiveness of alcohol-gel hand hygiene practice. @*Methods@#From March 2016 to September 2018, we analyzed the cross-correlation between the incidence of MDRO and the HH compliance each month at Gyeongsang National University Changwon Hospital. We employed an experiment to observe the effect of alcohol gel hand hygiene practice on the reduction of organisms on the hand surface using the handagar plates. @*Results@#Among the MDRO, only vancomycin-resistant enterococci (VRE) showed a moderate correlation with the HH rate (r = 0.55). The hand-agar plate experiment showed a significant bacterial reduction for inadequate HH (mean 3.47 CFU) and optimal HH (mean, 0.84 CFU) than before HH (mean, 11.56 CFU) (n = 32, P = 0.006). @*Conclusion@#The incidence of VRE showed a moderate correlation with HH among MDRO in the longitudinal analysis. HH practice was more effective in preventing the spread of VRE compared with other MDRO in our institute. Optimal alcohol-gel HH practice can effectively remove bacteria on the hand surface.

The Association between Thyroid Function and Metabolic Syndrome in Euthyroid Korean Male Adults: Korean National Health and Nutrition Examination Survey VI

BACKGROUND: Thyroid hormones are one of the key factors involved in energy, lipid, and glucose metabolisms. Many studies have been conducted to establish the association between thyroid function and metabolic syndrome. This study aimed to identify the association between thyroid hormone and metabolic syndrome in euthyroid Korean male adults.METHODS: Using data from the sixth Korea National Health and Nutrition Examination Survey from 2013 to 2015, this cross-sectional study of 2,285 male adults was conducted. Subjects who had thyroid diseases and were not euthyroid were excluded. The included subjects were divided into four groups according to free thyroxine (fT4) and thyroid-stimulating hormone levels. We analyzed the prevalence and adjusted odds ratio of metabolic syndrome according to thyroid hormone levels.RESULTS: The prevalence of metabolic syndrome and its components decreased constantly from the lowest fT4 quartile to the highest fT4 quartile. Compared with that in the lowest fT4 quartile, the adjusted odds ratio of hypertriglyceridemia in the highest fT4 quartile was 0.651.CONCLUSION: In euthyroid subjects, fT4 levels are associated with metabolic syndrome and all its components.

The effects of head rotation and tilt on oral pressure and muscle activity / 대한해부학회지

Factors Associated with Influenza Vaccination Location in Korean Adult Population

BACKGROUND: Increasing the influenza vaccination rate is important because influenza infection can cause serious illness or death. One way to increase vaccination rates is to expand the number of vaccination sites. This study examined the location of influenza vaccination in 2016 according to sex, age, socioeconomic status, and health behavior variables.METHODS: The study included 2,485 subjects from the Korean National Health and Nutrition Examination Survey aged 19 years or older who had received the vaccine. Variables that could affect health behaviors were examined by the chi-square test or t-test. The odds ratios (ORs) of public health center inoculations between different income and education groups, adjusted for age and sex, were analyzed using multivariate logistic regression.RESULTS: People aged 65 years or older, those living in rural areas, those with low incomes, those with up to elementary school education, and those with underlying diseases had the lowest vaccination rates at medical clinics and hospitals (P-value<0.05). The ORs for public health center inoculations were significantly higher in those with lower incomes and those with elementary school education than in those with higher incomes and those with more than university level education (OR 2.50, 95% confidence interval [CI]; 1.67–3.77 and OR 2.60, 95% CI; 1.72–3.95, respectively).CONCLUSION: To improve the influenza vaccination rates at medical clinics and hospitals among groups with low vaccination rates, we need to actively encourage high-risk patients to receive vaccinations.

Impact of the Dynamic Change of Metabolic Health Status on the Incident Type 2 Diabetes: A Nationwide Population-Based Cohort Study

BACKGROUND: Metabolically healthy obese (MHO) is regarded as a transient concept. We examined the effect of the dynamic change of metabolic health status on the incidence of type 2 diabetes mellitus (T2DM) both in obese and normal weight individuals.METHODS: We analyzed 3,479,514 metabolically healthy subjects aged over 20 years from the Korean National Health Screening Program, who underwent health examination between 2009 and 2010, with a follow-up after 4 years. The relative risk for T2DM incidence until the December 2017 was compared among the four groups: stable metabolically healthy normal weight (MHNW), unstable MHNW, stable MHO, and unstable MHO.RESULTS: During the 4 years, 11.1% of subjects in the MHNW group, and 31.5% in the MHO group converted to a metabolically unhealthy phenotype. In the multivariate adjusted model, the unstable MHO group showed the highest risk of T2DM (hazard ratio [HR], 4.67; 95% confidence interval [CI], 4.58 to 4.77). The unstable MHNW group had a higher risk of T2DM than stable MHO group ([HR, 3.23; 95% CI, 3.16 to 3.30] vs. [HR, 1.81; 95% CI, 1.76 to 1.85]). The stable MHO group showed a higher risk of T2DM than the stable MHNW group. The influence of the transition into a metabolically unhealthy phenotype on T2DM incidence was greater in subjects with aged <65 years, women, and those with weight gain.CONCLUSION: Metabolically healthy phenotype was transient both in normal weight and obese individuals. Maintaining metabolic health was critical for the prevention of T2DM, irrespective of their baseline body mass index.

Anti-hyperglycemic effects and signaling mechanism of Perilla frutescens sprout extract

BACKGROUND/OBJECTIVES: Perilla frutescens (L.) Britton var. (PF) sprout is a plant of the labiate family. We have previously reported the protective effects of PF sprout extract on cytokine-induced β-cell damage. However, the mechanism of action of the PF sprout extract in type 2 diabetes (T2DM) has not been investigated. The present study was designed to study the effects of PF sprout extract and signaling mechanisms in the T2DM mice model using C57BL/KsJ-db/db (db/db) mice. MATERIALS/METHODS: Male db/db mice were orally administered PF sprout extract (100, 300, and 1,000 mg/kg of body weight) or rosiglitazone (RGZ, positive drug, 1 mg/kg of body weight) for 4 weeks. Signaling mechanisms were analyzed using liver tissues and HepG2 cells. RESULTS: The PF sprout extract (300 and 1,000 mg/kg) significantly reduced the fasting blood glucose, serum insulin, triglyceride and total cholesterol levels in db/db mice. PF sprout extract also significantly improved glucose intolerance and insulin sensitivity, decreased hepatic gluconeogenic protein expression, and ameliorated histological alterations of the pancreas and liver. Levels of phosphorylated AMP-activated protein kinase (AMPK) protein expression also increased in the liver after treatment with the extract. In addition, an increase in the phosphorylation of AMPK and decrease in the phosphoenolpyruvate carboxykinase and glucose 6-phosphatase proteins in HepG2 cells were also observed. CONCLUSIONS: Our results sugges that PF sprout displays beneficial effects in the prevention and treatment of type 2 diabetes via modulation of the AMPK pathway and inhibition of gluconeogenesis in the liver.

Schematic of mean thickness distribution on the lateral aspect of the canine frontal sinus as an experimental model of sinus surgery / 대한해부학회지

The dog frontal sinus may represent an alternative model dental implant research; its topographical resemblance to the maxillary sinus renders it a potentially favorable experimental environment. The aim of this study was thus to elucidate the anatomical configuration of the canine frontal sinus and histological characteristics, and to determine whether it could be a new canine experimental model for dental implant research. Twenty-four sides of canine frontal bones were harvested. The distance from the nasion to the emerging point of the lateral aspect of the canine frontal sinus was measured with the aid of Lucion software. The thicknesses of the canine frontal sinus wall were measured, and the two specimens stained with hematoxylin and eosin. The mean distance from the nasion to the emerging point of the lateral aspect of the canine frontal sinus was 16.0 mm. The mean thicknesses of the canine frontal bone at 3, 6, 9, 12, and 15 mm lateral to the midsagittal plane were 2.3, 2.7, 3.2, 3.8, and 3.7 mm, respectively. The canine frontal sinus was lined with pseudostratified ciliated columnar epithelium. These data suggest that the canine frontal sinus is a suitable alternative to the canine maxillary sinus as a model for studying various sinus augmentation protocols.

In vitro study of Streptococcus mutans adhesion on composite resin coated with three surface sealants

OBJECTIVES: Although the coating of surface sealants to dental composite resin may potentially reduce bacterial adhesion, there seems to be little information regarding this issue. This preliminary in vitro study investigated the adhesion of Streptococcus mutans (S. mutans) on the dental composite resins coated with three commercial surface sealants. MATERIALS AND METHODS: Composite resin (Filtek Z250) discs (8 mm in diameter, 1 mm in thickness) were fabricated in a mold covered with a Mylar strip (control). In group PoGo, the surfaces were polished with PoGo. In groups PS, OG, and FP, the surfaces polished with PoGo were coated with the corresponding surface sealants (PermaSeal, PS; OptiGuard, OG; Fortify Plus, FP). The surfaces of the materials and S. mutans cells were characterized by various methods. S. mutans adhesion to the surfaces was quantitatively evaluated using flow cytometry (n = 9). RESULTS: Group OG achieved the lowest water contact angle among all groups tested (p 0.05) or significantly lower (group OG, p < 0.001) bacterial adhesion when compared with the control group. CONCLUSIONS: The application of the surface sealants significantly reduced S. mutans adhesion to the composite resin polished with the PoGo.

Influence of the Food Intake Ability and the Number of Remaining Teeth on Oral Health Related Quality of Life in Some Elderly People / 치위생과학회지

Eating supports to gain energy and nutrition and improves quality of life. Ageing affects the food intake ability due to loss of natural teeth and the progressive muscle degeneration. Our objective was to investigate how the food intake ability (FIA) and the remaining teeth could influence on oral health related quality of life in the elderly. This study was performed with 503 elderly subjects living in Daejeon, Korea. The questionnaire with the FIA with 30 Korean food and Oral Health Impact Profile 14 (OHIP-14) and oral examination were surveyed. The five groups according to cluster analysis of FIA had the different numbers of remaining teeth and functional posterior teeth with opposing teeth or prosthesis significantly: group 1, 21.78±8.27 and 2.80±2.63; group 2, 16.75±7.87 and 2.16±2.44; group 3, 14.68±9.77 and 1.73±2.30; group 4, 9.93±8.13 and 0.78±1.68; group 5, 10.18±8.37 and 0.51±1.22. The more foods the subjects could masticate, the better oral health related quality of life they had. The medium FIA, soft FIA and the number of remaining teeth could explain 46% of OHIP-14, but hard FIA could not in the multiple regression model. We suggested to develop the oral health program for the elderly to be able to eat the food with medium physical property at least be helpful to improve oral health related quality of life.

Efficacy of various cleaning solutions on saliva-contaminated zirconia for improved resin bonding

PURPOSE: This study aimed to investigate the efficacy of cleaning solutions on saliva-contaminated zirconia in comparison to air-abrasion in terms of resin bonding. MATERIALS AND METHODS: For saliva-contaminated airabraded zirconia, seven cleaning methods)-no contamination (NC), water-spray rinsing (WS), additional airabrasion (AA), and cleaning with four solutions (Ivoclean [IC]; 1.0 wt% sodium dodecyl sulfate [SDS], 1.0 wt% hydrogen peroxide [HP], and 1.0 wt% sodium hypochlorite [SHC])-were tested. The zirconia surfaces for each group were characterized using various analytical techniques. Three bonded resin (Panavia F 2.0) cylinders (bonding area: 4.5 mm2) were made on one zirconia disk specimen using the Ultradent jig method [four disks (12 cylinders)/group; a total of 28 disks]. After 5,000 thermocycling, all specimens were subjected to a shear bond strength test with a crosshead speed of 1.0 mm/minute. The fractured surfaces were observed using an optical and scanning electron microscope (SEM). RESULTS: Contact angle measurements showed that groups NC, AA, IC, and SHC had hydrophilic surfaces. The X-ray photoelectron spectroscopy (XPS) analysis showed similar elemental distributions between group AA and groups IC and SHC. Groups IC and SHC showed statistically similar bond strengths to groups NC and AA (P>.05), but not groups SDS and HP (P<.05). For groups WS, SDS, and HP, blister-like bubble formations were observed on the surfaces under SEM. CONCLUSION: Within the limitations of this in vitro study, some of the cleaning solutions (IC or SHC) were effective in removing saliva contamination and enhancing the resin bond strength.