• The Journal of Korean Academy of Prosthodontics
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• v.33 no.1
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• pp.32-47
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• 1995

The purpose of this study was to determine the displacement of prosthesis & abutment and the stress distribution patterns induced in the periodontium by applying force to the fixed prosthesis. Two levels of periodontal support were compared using two-dimensional finite element stress analysis after placement of 3unit or 4 unit fixed partial denture(FPD) in case of missing of the lower first molar. Concentrated vertical load was delivered at the cusp tip of the second bicuspid or the central fossa of the pontic. The following results were obtained : 1. The greater the loss of alveolar bone in abutment teeth area, the greater the displacement of FPD and the stress concentration in alveolar bone around abutment. 2. The amount and direction of displacement and distribution of stress in the 4-unit FPD was better than those in the 3-unit FPD. 3. Multiple abutments reduced the amount of mesial and downward displacement of the weaked abutments and more uniformly distributed the stresses.

• Journal of Periodontal and Implant Science
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• v.42 no.6
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• pp.256-260
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• 2012

Purpose: Actinomycosis is an uncommon chronic granulomatous disease that presents as a slowly progressive, indolent, indurated infiltration with multiple abscesses, fistulas, and sinuses. The purpose of this article is to report on a case of actinomycosis with clinical findings similar to periodontitis. Methods: A 46-year-old female presented with recurrent throbbing pain on the right first and second molar of the mandible three weeks after root planing. Exploratory flap surgery was performed, and the bluish-gray tissue fragment found in the interproximal area between the two molars was sent for histopathology. Results: The diagnosis from the biopsy was actinomycosis. The clinical and radiographic manifestations of this case were clinically indistinguishable from periodontitis. The patient did not report any symptoms, and she is scheduled for a follow-up visit. Conclusions: The present study has identified periodontitis-mimicking actinomycosis. Actinomycosis should be included in the differential diagnosis in cases with periodontal pain and inflammation that do not respond to nonsurgical treatment for periodontitis. More routine submissions of tissue removed from the oral cavity for biopsies may be beneficial for differential diagnosis.

• Journal of Periodontal and Implant Science
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• v.40 no.2
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• pp.86-89
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• 2010

Purpose: Osteotome sinus floor elevation (OSFE) is an often-used technique of great utility in certain implant patients with resorbed posterior maxilla. Recently benign paroxysmal positional vertigo (BPPV) has been reported as an early postoperative complication following OSFE. Although OSFE-induced BPPV commonly resolves itself within a month without treatment, this complication can be a cause of trouble between the implant surgeon and patient. This report presents a case of BPPV following OSFE. Methods: A 27-year-old man without any significant medical problems and missing his maxillary right first molar, was scheduled for OSFE and simultaneous implant placement. Results: The patient suffered dizziness accompanied by nausea immediately after implant placement using OSFE. Following referral to the ear nose throat clinic, "right posterior canal BPPV" was diagnosed. Despite anti vertigo medication and a single episode of the Epley maneuver, the condition did not improve completely. The Epley maneuver was then applied 7 and 8 days later and the symptoms of BPPV disappeared. One year later, the patient remained symptom-free. Conclusions: Before sinus elevation with an osteotome, implant surgeons should screen out patients with a history of vertigo, to diminish the possibility of BPPV. Operators should be aware of BPPV symptoms. As the symptoms may be very incapacitating, immediate referral to an otorhinolaryngologist is recommended.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.11 no.1
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• pp.41-50
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• 1981

Radiographic features of maxillary sinusitis, types of mucosal thickening, types of bony wall change, and relationship between the radiographic features and symptoms of patients were observed and classified in the Waters' view of 360 patients with 441 maxillary sinuses demonstrating radiologic changes. And the classification of antral floor and pathologic change was observed in the 154 periapi- cal films. Finally, the value of orthopantomography in the diagnosis of maxillary sinusitis was evaluated in the 138 cases, The obtained results were as followings. 1. Among 441 maxillary sinuses examined by Waters' projection, mucosal thickening was seen in 56.7% and generalized opacification was seen in 36.3%. 2. Among 270 mucosal thickenings classified 8 types, overall regularly thickened type was the highest in incidence (36.3%). 3. Bony wall change was seen in 35.6% of all cases and the indistinct white line of the cortical plates was the highest in incidence (78.2%) among the 6 types. 4. Pain (41.9%) and pus discharge (21.0%) were the most frequent symptoms. And pus discharge, foul odor, and headache was more prevalent in type of generalized opacification than any other types. 5. Regular pneumatization involving all roots of premolars and molars was the highest in incidence (55.0%). The first molar presented the most frequent involvement (61.0%). 6. In orthopantomography, 46.4% showed apparent increased radiopacity and 23.9% showed suspicious increased radiopacity in comparison to Waters' projection.

• Imaging Science in Dentistry
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• v.36 no.3
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• pp.163-168
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• 2006

A 60-year-old female, who complained of delayed healing and swelling after extraction of left lower second molar during chemotherapy, visited our department. She had a history of a resection surgery of breast cancer and postoperative radiotherapy. The conventional radiographs showed diffuse permeative bone destruction in posterior mandibular body, which gave the first radiologic impression of osteonecrosis associated with radiotherapy or chemotherapy. And bone metastasis from the breast cancer was also considered in the differential diagnosis. On the enhanced computed tomography (ECT) the posterior mandibular body was occupied by a large expansile lesion showing central low attenuation with peripheral rim enhancement. Magnetic resonance images revealed that the low attenuated area on ECT did not show as high signal intensity as water on T2 weighted image and indicated solid component of a tumor. The final diagnosis was central squamous cell carcinoma. We present the diagnostic imaging features of the patient with special emphasis on the differential diagnosis.

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1346-1350
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• 2004

Pseudo-first order rate constants $(k_{obs})$ are reported for the following solvolyses in approximately isodielectric mixtures: 3- and 4-methoxybenzyl chloride, bromo- and chlorodiphenylmethane, and 4-chloro-, 4,4'-dichloro and 4-methyl-chlorodiphenylmethane in 0-80% v/v nitromethane-methanol mixtures; and bromo- and chlorodiphenylmethane and 4-methyl-chlorodiphenylmethane in various acetonitrile-methanol mixtures (in the range 0-50% v/v) at$25^{\circ}C.$ These data, and literature data for t-butyl halides (Cl, Br, and I), and for p-methoxybenzoyl chloride, show rate maxima in solvent compositions of ca. 30% aprotic cosolvent, explained by a stoichiometric solvent effect on electrophilic solvation. Linear relationships are observed between $(k_{obs})/[MeOH]^2$ and [AP]/[MeOH], where [AP] refers to the molar concentration of aprotic cosolvent. The results are consistent with competing third order contributions to $k_{obs}$, $k_{MM}[MeOH]^2$ with hydrogen-bonded methanol as electrophile, and $k_{MAP}[MeOH][AP]$ with hydrogen-bonding disrupted by the aprotic solvent.

• Journal of the Korean Ceramic Society
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• v.20 no.1
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• pp.43-48
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• 1983

The formation of strontium titanate from several molar $SrCO_3$ and $TiO_2$ mixtures was studied in air and $CO_2$ gas Mixtures of $SrCO_3$ and $TiO_2$ were heated in air at 400-$600^{\circ}C$ DTA-TG was used to obtain thermal histories of simples heated in air and $CO_2$ gas. X-ray diffraction analysis was used to determine both the phase composition and the amounts of each phase present. The phase relationship of various compounds $SrTiO_3$, $Sr_2TiO_4$, $Sr_2Ti_3O_7$ and $Sr_4Ti_3O_{10}$ formed by the sintering in each composition was shown by the calibration curves. High temperature X-ray analysis was used to determine both the formation process and deformation process of each products. Small amount of SrTiO3 is formed first at the surface af contact SrTiO3 reacts with $SrCO_3$ to form Sr2TiO4 this is affected on the $CO_2$ pressure.

• Journal of The Korean Dental Society of Anesthesiology
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• v.11 no.2
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• pp.164-171
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• 2011

Altered consciousness may be the first clinical sign of a serious medical problem that requires immediate and intensive therapy to maintain life. There are many causes of the loss of consciousness in the dental office setting, such as, vasodepressor syncope, drug administration or ingestion, orthostatic hypotension, epilepsy, hypoglycemic reaction, acute adrenal insufficiency, cerebrovascular accident, hyperglycemic reaction, acute myocardial infarction, acute allergic reaction and hyperventilation. This is a case report of syncope and coma during endodontic treatment of a maxillary third molar under local infiltration anesthesia in multiple medically compromised patient. The main cause was thought to be hypoglycemic reaction. The patient was transferred to the medical emergency room and cared properly by the emergency medical physicians. The prognosis was good.

• Restorative Dentistry and Endodontics
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• v.42 no.1
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• pp.60-64
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• 2017

Root canal anatomy is complex, and the recognition of anatomic variations could be a challenge for clinicians. This case report describes the importance of cone beam computed tomographyic (CBCT) imaging during endodontic treatment. A 23 year old woman was referred by her general dental practitioner with the chief complaint of spontaneous pain in her right posterior maxilla. From the clinical and radiographic findings, a diagnosis of symptomatic irreversible pulpitis was made and endodontic treatment was suggested to the patient. The patient underwent CBCT examination, and CBCT scan slices revealed seven canals: three mesiobuccal (MB1, MB2, and MB3), two distobuccal (DB1 and DB2), and two palatal (P1 and P2). Canals were successfully treated with reciprocating files and filled using single-cone filling technique. Precise knowledge of root canal morphology and its variation is important during root canal treatment. CBCT examination is an excellent tool for identifying and managing these complex root canal systems.

• Journal of the Korean institute of surface engineering
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• v.5 no.3
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• pp.77-85
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• 1972

A method of preparation of synthetic ignorgaic coating on copper (patina) has been presented . An Eh--pH diagram was constructed for the present Cu-H2O-SO$_4$ system using the most recently available thermodynamic data. In the path of the patination at room temperature the general behaviour of copper in acidic copper sulfate solutions with potassium chlorate as an oxidizing agent appeared to follow those predictable in this Eh-pH diagram. In the presence 0.05 molar cupric sulfate at a temperature of about 28$^{\circ}C$ a green brochantite (CuSO$_4$$.$3Cu(OH)$_2$) layer was formed on copper sheet in 20 days. In a solution having an initial pH of 3.5 the development of a brochantite coating has been observed to take place in two stages. In the first, a layer of cuprous oxide formed on the copper at a relatively rapid rate. In the ensuing step the outer layer of cuptrite was oxidized at much slower rate to form brochantite. The syntetic coatings appeared to consist of crystal-lites of brochanitite growing perpendicular to the cuprose oxide surface. The outer tips of the -crystallites were reasily broken off and gave to the layer a rather chalky character. Underneath, at the brochantite Cu$_2$O interface, however, the green layers were firmely attached. The effect of reagent concentration , solution agitation , and moderate temperature increase were investigated to improve the quality of coating. So also in a qualitative way were the effect of light.