• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.308-314
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• 2017

PURPOSE. The purpose of this study was to analyze the retention force changes and wear behaviours of double-crown systems over long-term use. MATERIALS AND METHODS. Ten groups, each consisting of six samples, were evaluated. Specifically, casting gold alloy primary crown - casting gold alloy secondary crown (AA), laser sintering primary crown - laser sintering secondary crown (LL), casting Cr alloy primary crown - casting Cr alloy secondary crown, (CC) zirconia primary crown - electroformed secondary crown (ZA), and CAD/CAM titanium alloy primary crown - CAD/CAM titanium alloy secondary crown (TT) groups were evaluated at cone angles of $4^{\circ}$ and $6^{\circ}$. The samples were subjected to 5,000 insertion-separation cycles in artificial saliva, and the retention forces were measured every 500 cycles. The wear levels were analyzed via SEM at the beginning and end of the 5,000 cycles. RESULTS. In all samples, the retention forces increased when the conus angle decreased. The highest initial and final retention force values were found in the $LL-4^{\circ}$ group (32.89 N-32.65 N), and the lowest retention force values were found in the $ZA6^{\circ}$ group (5.41 N-6.27 N). The ZA groups' samples showed the least change in the retention force, and no wear was observed. In the other groups, wear was observed mostly in the primary crowns. CONCLUSION. More predictable, clinically relevant, and less excursive retention forces can be observed in the ZA groups. The retention force values of the LL groups were statically similar to those of the other groups, except the ZA groups.

• Journal of the korean academy of Pediatric Dentistry
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• v.47 no.2
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• pp.219-227
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• 2020

Tooth eruption involves a complex developmental process of tooth migration from the dental follicular origin to the final occlusion position in the oral cavity via the alveolar process. Disturbance of tooth eruption can occur at any point in a series of eruption stages; however, horizontal impaction of the mandibular first molar and primary retention of the primary mandibular second molar are rarely observed simultaneously. This study describes the treatment for two cases of horizontally impacted first molar with primary retention of primary molar. The primary retention of the primary mandibular second molar was extracted, and orthodontic traction was applied to the horizontally impacted primary mandibular first molar. Subsequently, displacement of the premolar tooth bud was improved and space regaining for eruption was achieved, guiding to normal eruption of the first molar.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.4
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• pp.314-320
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• 2013

With a prevalence rate of 0.01%, the presence of eruption disturbances of mandibular first molar has rarely been in populations. Eruption disturbances of permanent molars have been usually manifested as impaction, primary retention, and secondary retention. The treatments of eruption disturbances are carried out by: periodic observation; surgical exposure; forced eruption after surgical exposure; forced eruption with luxation; surgical repositioning; and extraction. This case report show successfully erupted mandibular first molars by various treatment methods on five patients diagnosed with impaction, primary retention, and secondary retention, respectively. Eruption disturbances of the mandibular first molar can be properly diagnosed with impaction, primary retention, and secondary retention by clinical and radiographic examination at normal eruption time of the mandibular first molar. The treatment should be done synthetically, considering eruption state of affected tooth, the relationship between the affected tooth and the adjacent or opposite tooth, the patient's age, treatment compliance, and economic state.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.1-10
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• 2008

Synthetic mineral microparticles (SMM) is a patented system which has been developed to promote drainage of water and retention of fine particles during papermaking. It is shown in patents that the SMM system can have advantages in both of drainage and retention, compared with montmorillonite (bentonite), which is one of the most popular materials presently used in this kind of application. Turbidity and gravity drainage time were measured using a Britt-Jar test with representative SMM formulations, in order to confirm the efficacy of SMM covering a wide range of compositions and discover effects of some key variables that have the potential to lead to unexpected advantages in terms of the effectiveness of the microparticles, when used in combination with a cationic polyacrylamide treatment of papermaking furnish. An iron silicate showed highest retention performance, as well as suitably fast drainage time relative to other metal silicate and bentonite. Zinc silicate improved retention and drainage. SMM synthesized from aluminum sulfate ($Al_2(SO_4){_3}$) did not show a benefit in retention and drainage, relative to bentonite. SMM synthesized from aluminum chloride ($AlCl_3$) performed better in drainage and retention than bentonite when the Al/Si ratios were 0.76 and 1.00. It was found that when the Al/Si ratio and neutralization are considered, pH variation due to the change of Al/Si ratio can be a key factor to control the size of primary metal silicate particles and the degree of coagulation of the primary particles.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.227-237
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• 2005

Eruptive disturbance of the permanent lower first molar is an uncommon condition caused by physical barriers on the eruption path or failure of the eruptive mechanism. Once eruptive disturbance of the permanent lower first molar is diagnosed. treatment should be started as soon as possible to establish a normal eruption pathway and to avoid any detrimental effects on the developing occlusion A case of primary retention of the mandibular first permanent molar treated with operculectomy and forced eruption which showed good treatment results and stability is described

• Journal of muscle and joint health
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• v.30 no.2
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• pp.103-110
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• 2023

Purpose: The present study examined the psycho-emotional factors that affect the retention intention among advanced beginner-stage nurses. Methods: A cross-sectional study was conducted using a convenience sample of 118 nurses with a work experience of at least one to three years of work experience in a university hospital in Suwon, Korea. Structured questionnaires were used to assess retention intention, emotional labor, and resilience. Multiple regression analysis was used to examine factors affecting retention intention. Results: Retention intention had a moderate mean score (4.75 out of 8). Factors influencing participants' retention intention were founded in the order of resilience (β=.29, p<.001) and emotional labor (β=-.20, p=.011) after adjusting nursing satisfaction as a covariate. The multiple regression model accounted for 42% of the variance in retention intention (p<.001). Conclusion: Resilience and emotional labor may be primary factors influencing retention intention of advanced beginner-stage nurses. Therefore, this study finding suggested that psycho-emotional factors such as emotional labor and resilience should be considered while designing programs to increase nurses' retention intention.

• Dementia and Neurocognitive Disorders
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• v.17 no.3
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• pp.110-119
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• 2018

Background and Purpose: To analyze $^{18}F-THK5351$ positron emission tomography (PET) scans of patients with clinically diagnosed nonfluent/agrammatic variant primary progressive aphasia (navPPA). Methods: Thirty-one participants, including those with Alzheimer's disease (AD, n=13), navPPA (n=3), and those with normal control (NC, n=15) who completed 3 Tesla magnetic resonance imaging, $^{18}F-THK5351$ PET scans, and detailed neuropsychological tests, were included. Voxel-based and region of interest (ROI)-based analyses were performed to evaluate retention of $^{18}F-THK5351$ in navPPA patients. Results: In ROI-based analysis, patients with navPPA had higher levels of THK retention in the Broca's area, bilateral inferior frontal lobes, bilateral precentral gyri, and bilateral basal ganglia. Patients with navPPA showed higher levels of THK retention in bilateral frontal lobes (mainly left side) compared than NC in voxel-wise analysis. Conclusions: In our study, THK retention in navPPA patients was mainly distributed at the frontal region which was well correlated with functional-radiological distribution of navPPA. Our results suggest that tau PET imaging could be a supportive tool for diagnosis of navPPA in combination with a clinical history.

• Journal of the korean academy of Pediatric Dentistry
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• v.24 no.4
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• pp.781-787
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• 1997

In spite of the improvements of the techniques in the field of preventive dentistry, many children still present with extensive destruction of primary anterior teeth. Not only the practioner must consider the pulp state of the primary incisor, but also restore the form, function and esthetics of the tooth. Restorative treatment of primary incisor tooth requires durability, retention and esthetics. Stainless steel crowns used in restoring primary anterior teeth is retentive and durable in comparison with the composite resin, celluloid crown. But they are not esthetic. To enhance the esthetics of the anterior stainless steel crown without reducing its superior retention, an open-face stainless steel crown has been suggested. Several authors have suggested cutting away the labial portion of the stainless steel crown and placing the composite resin in that area. By following this technique, the practioner can prepare a retentive, durable, and esthetic restoration for primary teeth which have suffered from extensive loss of teeth structure. In addition, the single missing primary anterior teeth can be successfully restored by soldering the stainless steel crown together. Open-face stainless steel crown is indicated in the areas of large interproximal lesions involving incisal edge, crown fracture with pulp exposure and congenital malformation of the teeth. By this technique, the practioner can restore primary anterior teeth successfully regardless of the amount of remaining tooth structure, bruxism habit and presence of attrition. In this case, rampant caries with extensive loss of tooth structure and single missing of primary anterior tooth hart been successfully treated with open-face stainless steel crown.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.61-66
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• 2006

Over the past 20 years there has been a revolution involving the use of nano or macro size particles as drainage and retention systems during the manufacture of paper. More recently a group of patented technologies called Synthetic Mineral Microparticles (SMM) has been invented and developed. This system has potential to further promote the drainage of water and retention of fine particles during papermaking. Prior research, as well as our on preliminary research showed that the SMM system has advantages in both of drainage and retention compared with montmorillonite (bentonite), which one of the most popular materials presently used in this kind of application. In spite of the demonstrated advantages of this SMM system, the properties and activity of SMM particles in the aqueous state have not been elucidated yet. Streaming current titrations with highly charged polyelectrolytes were used to measure the charge properties of SMM and to understand the interactions among SMM particles, fibers, fiber fines, and cationic polyacrylamide (cPAM) as a retention aid. It was found that pH profoundly affects the charge properties of SMM, due to the influence of Al-ions and the Si-containing particle surface. SEM pictures, characterizing the morphology, geometry and size distribution of SMM, showed an broad distribution of primary particle size. Dilution of SMM mixturee appeared to wash out particles smaller than 100 nm from the surface of larger particles, which themselves appeared to be composed of fused primary particles. DSC thermoporometry was used to measure the size distribution of nanopores within SMM particles.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.7
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• pp.255-264
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• 2021

The purpose of this study is to analyze the role of customer value and customer trust as a mediator of flexibility influence on customer retention. The study applies SEM tools with WarpPLS analysis and translates customer value and customer trust as mediation. This study was organized into three parts: exploratory research, descriptive research, and explanatory research. The quantitative approach in this study uses a survey method by taking samples from the population. This is a latent variable that is measured using a research instrument in the form of a questionnaire. The survey was conducted by distributing questionnaires to respondents. This research was conducted at PT. Nusa Prima Logistics Terminal Teluk Lamong by taking primary data, in the form of assessments or perceptions from respondents, so a survey was conducted by submitting a questionnaire directly to 194 respondents. Quantitative data analysis was performed using Structural Equation Modeling (SEM) to answer the research hypothesis. Flexibility is very influential in increasing customer retention so to develop customer retention, it is necessary to increase flexibility, customer value, and customer trust. The novelty in this research lies in identifying the role and position of customer value and customer trust as mediation that affect customer retention.