• Journal of Periodontal and Implant Science
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• v.43 no.5
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• pp.227-232
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• 2013

Purpose: The receptor activator of nuclear factor kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system plays a significant role in osteoclastogenesis, activation of osteoclasts, and regulation of bone resorption. This study aimed to evaluate the use of the salivary soluble RANKL (sRANKL)/OPG ratio as a diagnostic marker for periodontitis in nonsmokers. Methods: Twenty-five patients with chronic periodontitis and 25 individuals with a healthy periodontium were enrolled in this study. Samples containing 5 mL of unstimulated saliva were obtained from each subject. Salivary sRANKL and OPG concentrations were determined using a standard enzyme-linked immunosorbent assay. Statistical analysis was performed using SPSS ver. 18.0. Results: The levels of sRANKL and OPG were detectable in all of the samples. Positive relationships were found between the plaque index and clinical attachment level and both the salivary concentration of sRANKL and the salivary sRANKL/OPG ratio (P<0.05). The salivary concentration of sRANKL and the sRANKL/OPG ratio were significantly higher in the periodontitis group than in the healthy group (P=0.004 and P=0.001, respectively). In contrast, the OPG concentration showed no significant differences between the groups (P=0.455). Conclusions: These findings suggest that the salivary sRANKL/OPG ratio may be helpful in the screening and diagnosis of periodontitis. However, longitudinal studies with larger populations are needed to confirm these results.

• The korean journal of orthodontics
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• v.43 no.6
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• pp.288-293
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• 2013

Objective: This study was aimed at comparing the mandibular arch forms of Korean and Vietnamese patients by using facial axis (FA) points on three-dimensional (3D) models. Methods: Mandibular casts of 68 Korean (Class I malocclusion, 30; Class II malocclusion, 38) and 78 Vietnamese (Class I malocclusion, 41; Class II malocclusion, 37) patients were scanned in their occluded positions and grouped according to arch form (tapered, ovoid, and square). The FA point of each tooth was digitized on the 3D mandibular models. The measurements and frequency distributions of the arch forms were compared between the ethnic groups. Results: The Vietnamese patients had significantly greater intercanine depth and intercanine and intermolar width-to-depth ratios than the Korean patients (p < 0.05). The frequency distributions of the arch forms were also significantly different (p = 0.038), but no sexual dimorphism was found. Conclusions: Vietnamese people tend to have deeper and wider arches than Korean people. The three arch forms are evenly distributed in Korean people, but Vietnamese people frequently have square arches. Clinicians should identify the correct arch form of an ethnic group before initiating orthodontic treatment.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.19
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• pp.8489-8493
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• 2014

Objective: To verify the basic preoperative evaluation in the discrimination between benign and malignant adnexal masses in our clinical practice. Materials and Methods: Data were collected on the records of 636 women with adnexal masses who had undergone surgery either by open or endoscopic approaches. Those with obvious signs of malignancy, any history of cancer, emergency surgeries without basic evaluation were excluded. The preoperative features by age, ultrasound and serum Ca125 level were compared with final histopathological diagnosis at the four departments of the institution. These are the general gynecology (Group 1: exploratory laparotomy), the gynecologic endoscopy (Group 2: laparoscopy and adnexectomy), the gynecological oncology (Group 3: staging laparotomy) and the gynecologic endocrinology and infertility (Group 4: laparoscopy and cystectomy). Results: There were simple and complex cyst rates of 22.3% and 77.2%, respectively. There were 86.3% benign, 4.1% (n:20) borderline ovarian tumor (BOT) and 6.4% (n:48) malignant lesions. There were 3 BOT and 9 ovarian cancers in Group 1 and one BOT and two ovarian cancer in the Group 2. During the surgery, 15 BOT (75%) and 37 ovarian cancer (77%) were detected in the Group 3, only one BOT was encountered in the Group 4. The risk of rate of unsuspected borderline or focally invasive ovarian cancer significantly increased by age, size, complex morphology and Ca125 (95% CI, OR=2.72, OR=6.60, OR=6.66 and OR=4.69, respectively). Conclusions: Basic preoperative evaluation by comprehensive ultrasound imaging combined with age and Ca125 level has proved highly accurate for prediction of unexpected malignancies. Neither novel markers nor new imaging techniques provide better information that allow clinicians to assess the feasibility of the planned surgery; consequently, the risk of inadvertent cyst rupture during laparoscopy may be significantly decreased in selected cases.

• The Journal of Advanced Prosthodontics
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• v.9 no.3
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• pp.143-151
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• 2017

PURPOSE. The design of the attachment must provide an optimum stress distribution around the implant. In this study, for implant overdentures with a bar/clip attachment or a locator attachment, the stress transmitted to the implant in accordance with the change in the denture base length and the vertical pressure was measured and analyzed. MATERIALS AND METHODS. Test model was created with epoxy resin. The strain gauges made a tight contact with implant surfaces. A universal testing machine was used to exert a vertical pressure on the mandibular implant overdenture and the strain rate of the implants was measured. RESULTS. Means and standard deviations of the maximum micro-deformation rates were determined. 1) Locator attachment: The implants on the working side generally showed higher strain than those on the non-working side. Tensile force was observed on the mesial surface of the implant on the working side, and the compressive force was applied to the buccal surface and on the surfaces of the implant on the non-working side. 2) Bar/clip attachment: The implants on the both non-working and working sides showed high strain; all surfaces except the mesial surface of the implant on the non-working side showed a compressive force. CONCLUSION. To minimize the strain on implants in mandibular implant overdentures, the attachment of the implant should be carefully selected and the denture base should be extended as much as possible.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.110-117
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• 2017

PURPOSE. This laboratory study assessed the effect of different dentin cleaning procedures on shear bond strength of resin cements for recementing prosthesis. MATERIALS AND METHODS. A $4{\times}4$ flat surface was prepared on the labial surface of 52 maxillary central incisors. Metal frames ($4{\times}4{\times}1.5mm$) were cast with nickel-chromium alloy. All specimens were randomly divided into 2 groups to be cemented with either Panavia F2.0 (P) or RelyX Ultimate (U) cement. The initial shear bond strength was recorded by Universal Testing Machine at a crosshead speed of 0.5 mm/min. Debonded specimens were randomly allocated into 2 subgroups (n = 13) according to the dentin cleaning procedures for recementation. The residual cement on bonded dentin surfaces was eliminated with either pumice slurry (p) or tungsten carbide bur (c). The restorations were rebonded with the same cement and were subjected to shear test. Data failed the normality test (P < .05), thus were analyzed with Mann Whitney U-test, Wilcoxon signed rank test, and two-way ANOVA after logarithmic transformation (${\alpha}=.05$). RESULTS. The initial shear bond strength of group P was significantly higher than group U (P = .001). Pc and Uc groups presented higher bond strength after recementation compared to the initial bond strength. However, it was significant only in Pc group (P = .034). CONCLUSION. The specimens recemented with Panavia F2.0 provided higher bond strength than RelyX Ultimate cement. Moreover, a tungsten carbide bur was a more efficient method in removing the residual resin cement and increased the bond strength of Panavia F2.0 cement after recementation.

• The korean journal of orthodontics
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• v.46 no.4
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• pp.189-198
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• 2016

Objective: The purpose of this study was to analyze stress distributions in the roots, periodontal ligaments (PDLs), and bones around cylindrical and tapered miniscrews inserted at different angles using a finite element analysis. Methods: We created a three-dimensional (3D) maxilla model of a dentition with extracted first premolars and used 2 types of miniscrews (tapered and cylindrical) with 1.45-mm diameters and 8-mm lengths. The miniscrews were inserted at $30^{\circ}$, $60^{\circ}$, and $90^{\circ}$ angles with respect to the bone surface. A simulated horizontal orthodontic force of 2 N was applied to the miniscrew heads. Then, the stress distributions, magnitudes during miniscrew placement, and force applications were analyzed with a 3D finite element analysis. Results: Stresses were primarily absorbed by cortical bone. Moreover, very little stress was transmitted to the roots, PDLs, and cancellous bone. During cylindrical miniscrew insertion, the maximum von Mises stress increased as insertion angle decreased. Tapered miniscrews exhibited greater maximum von Mises stress than cylindrical miniscrews. During force application, maximum von Mises stresses increased in both groups as insertion angles decreased. Conclusions: For both cylindrical and tapered miniscrew designs, placement as perpendicular to the bone surface as possible is recommended to reduce stress in the surrounding bone.

• The korean journal of orthodontics
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• v.46 no.4
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• pp.242-252
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• 2016

Objective: Orthodontic mini-implants (OMI) generate various horizontal and vertical force vectors and moments according to their insertion positions. This study aimed to help select ideal biomechanics during maxillary incisor retraction by varying the length in the anterior retraction hook (ARH) and OMI position. Methods: Two extraction models were constructed to analyze the three-dimentional finite element: a first premolar extraction model (Model 1, M1) and a residual 1-mm space post-extraction model (Model 2, M2). The OMI position was set at a height of 8 mm from the arch wire between the second maxillary premolar and the first molar (low OMI traction) or at a 12-mm height in the mesial second maxillary premolar (high OMI traction). Retraction force vectors of 200 g from the ARH (-1, +1, +3, and +6 mm) at low or high OMI traction were resolved into X-, Y-, and Z-axis components. Results: In M1 (low and high OMI traction) and M2 (low OMI traction), the maxillary incisor tip was extruded, but the apex was intruded, and the occlusal plane was rotated clockwise. Significant intrusion and counter-clockwise rotation in the occlusal plane were observed under high OMI traction and -1 mm ARH in M2. Conclusions: This study observed orthodontic tooth movement according to the OMI position and ARH height, and M2 under high OMI traction with short ARH showed retraction with maxillary incisor intrusion.

• The korean journal of orthodontics
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• v.46 no.4
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• pp.253-265
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• 2016

In the present report, we describe the successful use of miniscrews to achieve vertical control in combination with the conventional sliding MBT$^{TM}$ straight-wire technique for the treatment of a 26-year-old Chinese woman with a very high mandibular plane angle, deep overbite, retrognathic mandible with backward rotation, prognathic maxilla, and gummy smile. The patient exhibited skeletal Class II malocclusion. Orthodontic miniscrews were placed in the maxillary anterior and posterior segments to provide rigid anchorage and vertical control through intrusion of the incisors and molars. Intrusion and torque control of the maxillary incisors relieved the deep overbite and corrected the gummy smile, while intrusion of the maxillary molars aided in counterclockwise rotation of the mandibular plane, which consequently resulted in an improved facial profile. After 3.5 years of retention, we observed a stable, well-aligned dentition with ideal intercuspation and more harmonious facial contours. Thus, we were able to achieve a satisfactory occlusion, a significantly improved facial profile, and an attractive smile for this patient. The findings from this case suggest that nonsurgical correction using miniscrew anchorage is an effective approach for camouflage treatment of high-angle cases with skeletal Class II malocclusion.

• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.150-156
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• 2020

PURPOSE. The aim of this study was to evaluate the effect of different surface finishing processes on the color stabilities of lithium disilicate glass-ceramics, zirconia-reinforced lithium silicate ceramics, and resin nanoceramics after artificial ageing. MATERIALS AND METHODS. 216 samples were prepared from 3 different CAD/CAM materials (LAVA Ultimate, IPS e.max CAD, VITA Suprinity) with A1 HT color at a size of 14 × 12 mm and a thickness of 0.5 ± 0.05 mm. Color measurements of the samples were performed with a spectrophotometer using color parameters and CIE Lab color system on a gray backing between baseline color and after 5000 cycles of artificial ageing in 4 stages (i.e. the first measurement before the treatment, the second measurement after polishing, the third measurement after cement application, and the fourth measurement after artificial ageing). The results were evaluated using the Variance analysis and Fisher's LSD test. RESULTS. Resin nanoceramics (LU) exhibited higher color change values than zirconia-reinforced lithium silicate (VS) and lithium disilicate (EC) ceramics after artificial ageing. Manual polishing and glazing resulted in similar color change for LU and VS (P>.05). In the EC group, glazing provided statistically different results as compared to the manual polishing and control groups (P<.05). Among the ceramic groups, color change values of the subgroup, which was treated by glazing, of the zirconia-reinforced lithium silicate (VS) and lithium disilicate (EC) samples were below the clinically acceptable level (ΔE < 3.5). CONCLUSION. The lowest color change for all stages was observed in Vita Suprinity.

• Journal of Korean Library and Information Science Society
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• v.12
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• pp.35-59
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• 1985

User fees have been employed by libraries as far back as the mid-1800s in both United States and England. By the late 1800s and early : 1900s, the charging of user fees for some library products and services had become a reality in many public and academic libraries. Yet the practice has created controversy when computer-aided reference service began to charge especially in the publicly funded libraries. There are two extream arguments on library reference service fees : one is for and the other is against. most fee o n.0, pponents base their stand on morality. They argue that charging fees for any service is wrong because it violates the user's right of access to information and regard it as an act of decrease human life chances as well as an act of censor. But those who favour fees argue that it is necessary to separate the rhetoric from the reality and to distinguish what libraries are from what they do. The study revealed that library has two options. One is strict free of charge and the other is charging for selected library services. Whatever options the library may take, library had to decide an overall reference service policy. The level and scope of service, audience, necessary fund (who and how) and many other physical and metaphysical things must be considered. However, the first option will necessary be to limit services while there is no loss of traditional philosophical service element. Yet, if to provide a wide range of choices and to create conditions more hospitable to competition from the private information sector and for better evolutional selection, the second option(fee-based service) gives more benefit to the users while there is a loss of fundamental service philosophy.