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1.  The effect of a desensitizer and CO2 laser irradiation on bond performance between eroded dentin and resin composite 
This study was aimed to evaluate effect of the desensitizing pretreatments on the micro-tensile bond strengths (µTBS) to eroded dentin and sound dentin.
Forty-two extracted molars were prepared to form a flat dentin surface, and then they were divided into two groups. Group I was stored in distilled water while group II was subjected to a pH cycling. Each group was then subdivided into three subgroups according to desensitizing pretreatment used: a) pretreatment with desensitizer (Gluma); b) pretreatment with CO2 Laser (Ultra Dream Pluse); c) without any pretreatment. All prepared surfaces were bonded with Single Bond 2 and built up with resin composite (Filtek Z250). The micro-tensile bond test was performed. Fracture modes were evaluated by stereomicroscopy. Pretreated surfaces and bonded interfaces were characterized by scanning electron microscope (SEM). The data obtained was analyzed by two-way ANOVA (α=0.05).
For both sound and eroded dentin, samples treated with desensitizer showed the greatest µTBS, followed by samples without any treatment. And samples treated with CO2 laser showed the lowest µTBS. SEM study indicated that teeth with eroded dentin appeared prone to debonding, as demonstrated by existence of large gaps between adhesive layers and dentin.
Pretreatment with Gluma increased the µTBS of Single Bond 2 for eroded and sound teeth. CO2 laser irradiation weakened bond performance for sound teeth but had no effect on eroded teeth.
PMCID: PMC4085239  PMID: 25006379
Tooth erosion; Adhesives; Tensile strength; Lasers; Gluma dentin desensitizer
2.  Physical stability of arginine-glycine-aspartic acid peptide coated on anodized implants after installation 
The aim of this study was to evaluate the stability of arginine-glycine-aspartic acid (RGD) peptide coatings on implants by measuring the amount of peptide remaining after installation.
Fluorescent isothiocyanate (FITC)-fixed RGD peptide was coated onto anodized titanium implants (width 4 mm, length 10 mm) using a physical adsorption method (P) or a chemical grafting method (C). Solid Rigid Polyurethane Foam (SRPF) was classified as either hard bone (H) or soft bone (S) according to its density. Two pieces of artificial bone were fixed in a customized jig, and coated implants were installed at the center of the boundary between two pieces of artificial bone. The test groups were classified as: P-H, P-S, C-H, or C-S. After each installation, implants were removed from the SRPF, and the residual amounts and rates of RGD peptide in implants were measured by fluorescence spectrometry. The Kruskal-Wallis test was used for the statistical analysis (α=0.05).
Peptide-coating was identified by fluorescence microscopy and XPS. Total coating amount was higher for physical adsorption than chemical grafting. The residual rate of peptide was significantly larger in the P-S group than in the other three groups (P<.05).
The result of this study suggests that coating doses depend on coating method. Residual amounts of RGD peptide were greater for the physical adsorption method than the chemical grafting method.
PMCID: PMC3675298  PMID: 23755331
RGD peptide; Physical stability; Chemical grafting; Physical adsorption; Dental implant
3.  Effect of two-phase fabrication method for the optimum fit of light-polymerized record bases 
The aims of this study were to suggest a method of fabrication of the record base using a light-polymerized resin by applying the two-phase fabrication method for the improvement of the fit of the record base and to compare the degree of fit according to the separation site.
In the edentulous cast of maxilla, four test groups were considered. In the first, second, third, and fourth test groups (n = 12 in each group) the separation was done at 0, 5, 10, and 15 mm, respectively below the alveolar crest along the palatal plane. For the control group, the record base was made without separating the two sections. The light-body silicone material was injected into the fitting surface of the record base. It was then placed onto the cast and finger pressure was applied to stabilize it in a seated position followed by immediate placement onto the universal test device. Finally, the mass of the impression material was measured after it was removed. ANOVA was performed using the SAS program. For the post-hoc test, the Wilcoxon Rank-Sum test and the Tukey-Kramer HSD test were performed (α = 0.05).
The control group and Group 3, 4 showed significant differences. The Group 3 and 4 showed significantly smaller inside gaps than the control group which was not made with the two-phase fabrication method.
The two-stage polymerized technique can improve the fit of the denture base particularly when the separation was made at 10 to 15 mm from the alveolar crest.
PMCID: PMC2994693  PMID: 21165278
Record base; Two-stage polymerization; Fit
4.  A comparison of the implant stability among various implant systems: clinical study 
To determine the change in stability of single-stage, three different design of implant systems in humans utilizing resonance frequency analysis for early healing period (24 weeks), without loading.
Twenty-five patients were included into this study. A total of 45 implants, three different design of implant systems (group A,C,R) were placed in the posterior maxilla or mandible. The specific transducer for each implant system was used. ISQ (implant stability quotient) reading were obtained for each implant at the time of surgery, 3, 6, 8, 10, 12, 24 weeks postoperatively. Data were analyzed for different implant type, bone type, healing time, anatomical locations.
For each implant system, a two-factor mixed-model ANOVA demonstrated that a significant effect on ISQ values (group A = 0.0022, C = 0.017, R = 0.0018). For each implant system, in a two-factor mixed model ANOVA, and two-sample t-test, the main effect of jaw position (P > .005) on ISQ values were not significant.
All the implant groups A, C and R, the change patterns of ISQ over time differed by bone type. Implant stability increased greatly between week 0 and week six and showed slow increase between week six and six months (plateau effect).
PMCID: PMC2994671  PMID: 21165252
Osseointegration; Implant stability; Magnetic resonance frequency analysis; Bone quality type
5.  Clinical Implications of Mandible and Neck Measurements in Non-Obese Asian Snorers: Ansan City General Population-Based Study 
Anthropometric abnormalities of the mandible and neck may contribute to snoring in non-obese Asians. The study evaluated the clinical implications of mandible and neck measurements in non-obese Asian snorers.
The external mandible and neck measurements (neck circumference, two lengths of neck, mandibular body angle, and lengths of mandibular ramus and body) were compared between snorers and non-snorers in a sample of 2,778 non-obese Koreans (1,389 males, 1,389 females) aged 40 to 69 years (mean, 48.47±7.72 years).
The overall prevalence of snoring was 64.7% (899/1,389) and 48.3% (671/1,389) in non-obese male and female subjects, respectively. In non-obese males, snorers had significantly a greater neck circumference (P<0.0001) and shorter mandibular body length (P=0.0126) than non-snorers. In non-obese females, snorers had significantly greater neck circumferences (P=0.0165), compared with non-snorers. However, there were no statistically significant differences in other variables between non-snorers and snorers.
Anthropometric abnormalities of the mandible and neck, including thick neck circumference in both genders and small mandible size in males, may be relevant contributing factors to snoring in non-obese Asian snorers.
PMCID: PMC3062226  PMID: 21461062
Asian; Population; Snoring; Mandible; Neck
6.  Risk assessment for clinical attachment loss of periodontal tissue in Korean adults 
The purpose of this study was to assess the prevalence and extent of clinical attachment loss of periodontal tissue and to find out variables related to clinical attachment loss (CAL) in Korean adults older than 40 years of age.
Data were collected from 2,519 subjects who were part of a cohort study conducted in Ansan city by Korea University Medical School for Korean Genome project. Age, sex, smoking, drinking, fast glucose, blood pressure, obesity and total cholesterol levels were examined. The oral examination included probing pocket depth, gingival recession and CAL of Ramford's teeth. The severity of periodontitis was classified based on the mean value of CAL. The relationship between each risk factor and the severity of CAL was independently estimated using the chi-square test, the test or one-way ANOVA. Multiple regression analysis was used to determine the significance of each factor in the periodontal disease.
The prevalences of clinical attachment between 1 and 3 mm, between 3 and < 5 mm, and ≥ 5 mm were 80.27%, 16.75% and < 1%, respectively. Although the univariate analysis showed age, gender, smoking, fasting glucose, blood pressure and total cholesterol levels were significantly related to the severity of CAL, multiple regression analysis indicated that age (P < .0001), gender (P < .0001) and smoking (P < .05) were only significantly related.
Older age, male gender and smoking were significant risk factor for the increase of CAL, and these may be useful indicators of periodontitis high-risk groups.
PMCID: PMC3076570  PMID: 21503190
Korean; Periodontal attachment loss; Periodontitis; Epidemiology; Risk factor
7.  Relationship between tooth loss and carotid intima-media thickness in Korean adults 
The aim of this study was to examine the relationship between tooth loss and sub-clinical atherosclerosis in Korean adults.
The subjects were part of a cohort study conducted in Ansan city by the Korea University medical school as part of the Korean Genome project. 749 subjects over than 40 years old were evaluated. After taking panoramic radiography, the amount of tooth loss was calculated. The intima-media thickness (IMT) was assessed by using ultrasonography at the common carotid artery. Traditional cardiovascular risk factors for atherosclerosis were also evaluated. The relationship between tooth loss and the IMT was evaluated using ANOVA with Scheffe's multiple comparison method in univariate analysis. Multiple regression analysis was also performed to determine the significance between the IMT and tooth loss.
With age, tooth loss increased, but there was no significant increase in other traditional cardiovascular risk factors. Univariate analysis revealed the IMT to be positively related with the amount of tooth loss. Regression analysis of the IMT in the anterior and posterior tooth loss revealed that only the posterior tooth loss was significantly related with the IMT at all sites of the common carotid artery (right far wall, P = .015; left far wall, P = .008; right near wall, P < .001; left near wall, P = .001).
This study verified the positive relationship between the increased tooth loss at the posterior area and the accumulation of atheroma in arteries.
PMCID: PMC3024501  PMID: 21264190
Korean; Tooth loss; Intima-media thickness (IMT); Atherosclerosis

Results 1-7 (7)