• Journal of Pharmaceutical Investigation
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• v.6 no.1
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• pp.26-32
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• 1976

Dicalcium phosphate dihydrate (DCPD) is the most widely-used dentifrice abrasive in non-therapeutic tooth-paste requiring, low abrasive level, high stability and excellent compatibility with other formulation ingredients. One of the difficulties encountered in the use of this material in tooth-paste is that unless storage of the product is maintained at a relative low temperature there is a distinct tendency to lose water of crystallization. Another difficulty which has been encountered is that there is a tendency for the product to become lumpy. Various means have been proposed for increasing the stability and overcoming the lumping tendency, most of which means comprise the addition of stabilizing agent. But there is not any report about the relationships between the mechanism of dehydration, physical properties, structure and manufacturing condition. In this experiment, DCPD were manufactured by methods of Moss' patent, its two varied and J.P.VIII, these were studied by means of stability test, IR spectra, and DTA. According to the manufacturing conditions, DCPD has different physical properties and structures, i. e., monoclinic system of low drying temperature, triclinic system of high drying temperature. Dehydration of DCPD may be supposed one step debydration at about $100^{\circ}$ and it finaly converts to ${\gamma}-pyrophosphate$ at about $465^{\circ}$ and if the drying temperature is high it becomes DCP anhydrous. DCPD made by Moss' patent is thought of the best polishing agent of tooth-paste.

• Restorative Dentistry and Endodontics
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• v.26 no.6
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• pp.464-484
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• 2001

When restoring a tooth, the dentist tries to choose the ideal material for existing situation. One criterion that is considered is its suitability for restoring coronal strength. As more tooth structure is removed, the cusps are weakened and susceptible to fracture. Further, this increased deformation may cause the formation of intermittent gaps at the margin between the hard tissue and the restoration, facilitating marginal leakage. The improvements in ceramic materials now make it possible for alternatives to amalgams, composites, and cast metal to be of offered for posterior teeth. Of the materials used, ceramics most closely approximates the properties of enamel. The introduction of computer-aided design/computer-aided manufacture(CAD/CAM) systems to restorative dentistry represents a major technological breakthrough. It is possible to design and fabricate ceramic restorations at a single appointment. Additionally, CAD/CAM systems eliminate certain errors and inaccuracies that are inherent to the indirect method and provide an esthetic restoration. The aim of this investigation was to study the loading characteristics of CAD/CAM ceramic inlay and to compare the stress distribution and displacement associated with different designs of cavity(the isthmus width and cavity depth). A human maxillary left first premolar was prepared with standard mesio-occlusal cavity preparation, as recommended by the manufacturer Ceramic inlay was fabricated with CEREC 2 CAD/CIM equipment and cemented into the prepared cavity. Three dimensional model was made by the serial photographic method. The cavity width was varied $\frac{1}{3}$, $\frac{1}{2}$ and $\frac{2}{3}$ of intercuspal distance between buccal and lingual cusp tip. The cavity depth was varied 1.5mm and 2.3mm. So six models were constructed to simulate six conditions. A point load of 500N was applied vertically onto the first node of the lingual slope from the buccal cusp tip. The stress distribution and displacement were solved using ANSYS finite element program(Swanson Analysis System). (omitted)

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.2
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• pp.135-142
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• 2023

Resin-bonded fixed partial denture (RBFPD)as known as Maryland bridge is is a well-known conservative method for its minimized invasion of the teeth for an anterior single tooth edentulous area. Despite of its various advantages, RBFPD was not widespread because of its high debonding rates, non-esthetic look or weak structure for material property. Currently, with the introduction of zirconia to dental material for RBFPD, Maryland bridge entered upon a new phase. Zirconia surmounts poor esthetics of metal framework, having proper strength, and overcomes ceramic's structural weakness, being sufficiently esthetic. In this case, edentulous area of maxillary left lateral incisor was restored using zirconia resin-bonded fixed partial denture. Restoration of missing tooth in anterior area was achieved using non-invasive and esthetic prosthesis, then we report this case as satisfactory results were obtained for both the operator and the patient.

• The Korean Journal of Malacology
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• v.31 no.4
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• pp.299-305
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• 2015

These studies were conducted to compare the radulae of six species (Nordotis madaka, N. gigantea, N. discus discus, N. discus hannai, Sulculus diversicolor diversicolor, and S. diversicolor supertexta) of the family Haliotidae in Korea using the scanning electron microscope. As a result, teeth of all species has asymmetry rhipidoglossate form and basic tooth formula of six Haliotids was >50-5-1-5-50< (one central tooth, five lateral teeth, and over the 50 marginal teeth on each side). Therefore it is difficult that all of the species can be detected sharply the difference of interspecies by comparisons of radulae.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.455-462
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• 2010

Patients often seek rehabilitative treatment for severely worn dentition. The etiology of noncarious tooth wear due to attrition, abrasion, and erosion is multifactorial. To treat the worn dentition, it is important to identify and eliminate and/or control the factors that contribute to excessive wear. Many situations requiring complete mouth rehabilitation present with the challenge of a lack of restorative space. To establish a correct occlusal plane and space for prostheses, it is necessary to increase vertical dimension. This may require an increase in occlusal vertical dimension. Also clinicians should be able to choose the appropriate restorative materials to achieve excellence in natural esthetics as well as proper biomechanics and durability. This article presents a method for altering occlusal vertical dimension to restore dentitions with limited restorative space due to loss of tooth structure.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.250-254
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• 2007

Dentigerous cysts are the most common type of developmental odontogenic cysts. They form as a result of a separation of the follicle from around the crown of an unerupted tooth. Usually this lesion can be asymptomatic. Such cysts are often discovered accidently on inspection of x-rays. In other advanced cases, cortical bone expansion, displacement of teeth, secondary infection can be observed. The treatment of dentigerous cyst is enucleation. And according to size, location of lesion and environmental structure marsupialization can be considered. However, Marsupialization takes long treatment time and, cystic tissues are remained so secondary surgery may be needed for total removal., Risks of oroantral fistula, damage on maxillary sinus wall and infraorbital nerve can be considered as complications of conventional surgical treatment of cysts located in maxillary sinus. We treated third molar origin dentogerous cyst located in maxillary sinus removing endoscopically both the tooth and an associated dentigerous cyst. We report our clinical experience with literature review.

• Journal of Drive and Control
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• v.14 no.1
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• pp.1-7
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• 2017

The power train of a concrete truck mixer reducer includes differential planetary gears to get a large reduction ratio for operating the mixer drum in a compact structure. These differential planetary gears are a very important part of the mixer reducer where strength problems are the main concern. Gear bending stress, gear compressive stress and scoring failure are the main concerns. Many failures in differential planetary gears are due to the insufficient gear strength and resonance problems caused by major excitation forces such as gear mating failure in the transmission. In the present study, where the excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate differential planetary gear critical speeds. Mode shapes and natural frequencies of the differential planetary gears are calculated by CATIA V5. These are used to predict gear resonance failures by comparing the working speed range with the critical speeds due to the gear transmission errors of the differential planetary gears.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.915-921
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• 2004

In this paper, we propose a printed monopole antenna called the saw tooth monopole antenna(STMA) with a very wide band. And impedance matching of the antenna for the wideband is achieved using a special matching structure to vary ground size of back plate. The proposed antenna is smaller than general $\lambda$/4 monopole antenna in size but provides a 2:1 VSWR bandwidth of about $89.6\%$. The radiation pattern is omni-directional at 0.8 GHz$\~$2.0 GHz with gain of about -0.02 dBi$\~$2.54 dBi.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.12
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• pp.105-112
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• 2020

The increase in the edentulous jaw which occurs in the aged population has led to personal dental health concerns. In the case of dental implant surgery, the duration of a patient's recovery depends on the surgical plan and their physicical ability. A device may be required to assist a physician in controlling vibration reduction of free-hand drilling and prescribing a good treatment plan that is suitable for the patient's condition. In this work, an artificial tooth-root implant assistant manipulator was studied. The structure and the vibration analysis of the dynamic restraint manipulator that is for drilling the alveolar bone in the mandible bone were performed, and the structural stability was analyzed. Further, a virtual prototype of an artificial tooth-root implant assisted manipulator was fabricated and tested. Hence, the state of the Remote Center of Motion (RCM) point and the driving state of the manipulator were confirmed. Furthermore, the drilling experiments were performed by using materials similar to a human jawbone in order to evaluate the performance of the drilling process that is operated using the assistant manipulator.

• Restorative Dentistry and Endodontics
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• v.49 no.3
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• pp.23.1-23.10
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• 2024

Objectives: Previous in vitro studies determined the whitening effects of bleaching products on stained resin composite surfaces. This in vitro study aimed to verify the effectiveness of a whitening system on composite resin previously subjected to pigmentation, specifically examining the depth of whitening effectiveness within the material structure. Materials and Methods: A commercially available nano-filled composite resin was used. Specimens were stained using a coffee-based solution and a 10% carbamide peroxide-based gel was employed as the whitening agent. The pigment's penetration and the effect of the bleaching gel were evaluated by measuring color (CieLab values) from the outer edge to the inner part of the specimens. Color measurements were taken at 14 points, starting from 0.1 mm from the external perimeter up to 3.0 mm. Results: Analysis of variance tests showed a statistically significant difference between the Control Group (CG), Pigmentation Group, and Whitening Group. The whitening agent was effective up to 1.5 mm in depth, with Whiteness index (W) values not statistically different from those of CG up to 0.5 mm in depth. Conclusions: Whitening agents on nano-filled resin composite previously pigmented appear effective in restoring the W to values similar to the original, particularly in the superficial layers of the sample.