• The korean journal of orthodontics
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• v.39 no.2
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• pp.83-94
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• 2009

Objective: The aim of this study was to investigate the 3-dimensional position of the center of resistance of the 4 maxillary anterior teeth, 6 maxillary anterior teeth, and the full maxillary dentition using 3-dimensional finite element analysis. Methods: Finite element models included the whole upper dentition, periodontal ligament, and alveolar bone. The crowns of the teeth in each group were fixed with buccal and lingual arch wires and lingual splint wires to minimize individual tooth movement and to evenly disperse the forces to the teeth. A force of 100 g or 200 g was applied to the wire beam extended from the incisal edge of the upper central incisor, and displacement of teeth was evaluated. The center of resistance was defined as the point where the applied force induced parallel movement. Results: The results of study showed that the center of resistance of the 4 maxillary anterior teeth group, the 6 maxillary anterior teeth group, and the full maxillary dentition group were at 13.5 mm apical and 12.0 mm posterior, 13.5 mm apical and 14.0 mm posterior, and 11.0 mm apical and 26.5 mm posterior to the incisal edge of the upper central incisor, respectively. Conclusions: It is thought that the results from this finite element models will improve the efficiency of orthodontic treatment.

• Korean Journal of Cleft Lip And Palate
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• v.6 no.1
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• pp.1-15
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• 2003

Cleft lip and palate deformity have unknown patterns of maxillofacial growth and development. The maxillofacial growth can be affected either by congenital or environmental factors such as infection and trauma. Surgical repair of cleft lip and palate may interfere the subsequent growth and development of maxillofacial region. The purpose of this study is to evaluate the characteristics of development of maxillofacial region in adult cleft lip and palate patients and to compare post-treat-ment craniofacial morphology between cleft lip and palate patients with secondary alveolar bone graft group and normal group. The material for this study consisted of 20 adult male patients with cleft lip and palate(mean 22.5, range 18-31) visited in Yeungnam University medical center. Cephalometric tracing and measurements were done by one investigator. Results were followed: The values of Na. perpendicular to point A, SNA angle and Pogonion to Na. perpendicualrwere -4.93±5.70, 76.45±4.69, and -6.38±6.73. The values of effective maxillary length, effective mandibular length, mandibular plane angle and facial axis angle were 85.6±4. 42, 123.88±7.10, 29.9±5.09 and 5.53±2.03. The value of upper incisors to point A was 3.95±2.74.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.1
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• pp.26-32
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• 2005

A tooth impaction means a state that a tooth does not erupt out of oral mucosa or alveolar bone for many reasons. The reasons for an impaction of the Maxillary central incisor are an odontoma, supernumerary tooth, space loss, prolonged remaining or early loss of a preceding deciduous tooth, abnormalities of crown or root caused by trauma of a deciduous tooth and an ectopic position of a tooth germ. In the case of the impacted maxillary incisor, a rapid mesial movement of a lateral incisor leads a space loss and a midline deviation can be happened. Furthermore, it can cause a cyst. When we treated a patient with an impacted central incisor early, we could see a better prognosis. It means an early diagnosis and an exact treatment are very important. Generally if the impaction is not severe or it is caused by a keratinized covering tissue, a surgical exposure can induce an eruption easily but an orthodontic force is recommended when an eruption does not happen after a surgical method, when the eruption path is too transpositioned to be corrected spontaneously and when an impacted tooth is located so deeply. In the treatment using an orthodontic force, careful considerations about a root length, pulp, and a periodontal tissue can improve the periodontal and esthetic prognosis for the long follow-up results. This case is using an orthodontic traction following a periodic observation and in no expectation of spontaneous eruption. After treatment of this case, I have got some knowledges, so I report this case.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.273-285
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• 2000

The aim of this investigation was to evaluate the differences of two canti-leyer springs by using a new simulation system. This was done using a Calorific machine that compared iron uprighting spring and root uprighting spring. The Calorific machine was designed to allow observation of the whole process of tooth moving, and is composed of three parts(a temperature regulating system, electro-thermodynamic teeth, and an artificial alveolar bone component). The experiment of both mechanics were repeated five times and measured two times. The intra-examiner agreement and inlet-examiner agreement were $96.54\%\;and\;95.73\%$ and these data were statistically tested by paired t-test. The obtained results were as follows. 1. Distal and buccal movement of the anchor teeth were observed greater in the root uprighting spring than the crown uprighting spring. 2. Crown uprighting spring showed distal movement of the crown of lower second molar for 3.29mm but root uprighting spring showed only 1.68mm. 3. Crown uprighting spring exhibited forward movement of mesial and distal root of the lower second molar for 3.91mm, 3.60mm but the root uprighting spring showed 6.76mm, 6.26mm.

• Journal of Periodontal and Implant Science
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• v.26 no.4
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• pp.1013-1021
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• 1996

There are many important factors in periodontal inflammation. $IL-1{\beta}$, $PGE_2$ and collagenase are predorminantly key factors. These inflammatory mediators induce gingival tissue and alveolar bone destruction. For the prevention and treatment of periodontal disease, it is necessary to inhibit $IL-1{\beta}$, $PGE_2$ production and collagenase activity. Ursodeoxycholic acid(UDCA) has immunomodulatory properties, and there is evidence that some natural extracts show antiinflammatory activity to some degree. The purpose of this study was to assess the inhibitory effect of UDCA and its mixture with natural extracts on $IL-1{\beta}$, $PGE_2$ production and collagenase activity. Accordingly we assessed the effect of UDCA and its mixture combined with some natural extracts on inhibition of $IL-1{\beta}$, $PGE_2$ production and collagenase activity. For the $IL-l{\beta}$ inhibition study, cultured cells were exposed to $25{\mu}g/ml$ LPS. $IL-1{\beta}$ activity was measured by $IL-1{\beta}$ enzyme immunoassay system. Human gingival fibroblasts were prepared and cells (l05/well) were seeded into culture plates. $rhIL-1{\beta}$ was added to induce $PGE_2$. The amount of $PGE_2$ in sample media was measured using enzyme immunoassay system. Crude collagenase was prepared from Porphyromonas gingivalis and collagenolytic activity was determined using a Collageno kit CLN-100. The test inhibitor was added to the assay mixture consisting of 0.1ml of 50mM Tris buffer(pH 7.5) and 0.2ml of substrate solution. UDCA and UDCA combined with natural extracts generally inhibited $IL-1{\beta}$ production. groups above 0.01% UDCA strongly inhibited $IL-l{\beta}$ synthesis. Both groups inhibited $IL-1{\beta}-induced$ synthesis of $PGE_2$. In low concentration, the degree of inhibition was as same as prednisolone. In high concentration, each group was superior to prednisolone. UDCA group and UDCA mixture group exerted a moderate inhibition of collagenolytic enzyme. The present study suggested that UDCA and its mixture with natural extracts could be further investigated as antiinflammatory drug for periodontal disease.

• Journal of Periodontal and Implant Science
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• v.37 no.1
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• pp.35-44
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• 2007

Periodontal ligament (PDL) is the connective tissue located between the tooth root and alveolar bone. In a previous study, PDLs22 was isolated as a PDL-specific gene by using subtractive hybrid-ization between cultured PDL fibroblasts and gingival fibroblasts. It was also suggested that PDLs22 plays important roles in the development, differentiation and maintenance of periodontal tissues. However, little is known about functional study of PDLs22 using recombinant protein in PDL fibroblast differentiation and periodontium formation. In this study, in order to produce the PDLs22 recombinat protein, PDLs22 expression vector were constructed and expressed its protein in various host cell and temperature conditions. The results were as follows: 1. PDLs22 protein was not strongly expressed In the induction system using pRSET-PDLs22 construct. 2. When the BL21(DE3) pLysS was used as a expression host, PDLS22 protein was strongly ex-pressed in the induction system using pHCEIIBNd-PDLs22 construct. 3. The PDLs22 protein was recognized at a molecular weight of 28 kDa in western blots. 4. Almost of the expressed PDLs22 protein was not soluble and observed like as inclusion body. 5. The protein solubility was not improved after modification of induction time and temperature during PDLs22 protein production. In this study, the system for the PDLs22 protein production was connstructed. However, the re-results suggest that further studies will be needed to produce the considerable amount of PDLs22 re-combinat protein, which can use for the periodontal regeneration.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.3
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• pp.571-577
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• 2008

Root fracture of primary teeth is relatively uncommon because the more pliable alveolar bone allows displacement of the tooth. Root fracture of primary teeth is occupied $2{\sim}7%$ in trauma pattern of primary teeth. A horizontal root fracture is classified based on the location of the fracture in relation to the root tip : the apical third, middle third, or cervical third of the root. The prognosis worsens the further cervically the fracture has occurrer. Root fracture of primary teeth should be treated by splinting the incisor to the adjacent normal teeth with a resin-wire splint for $8{\sim}12$ weeks. However, if a portion of the root is abscessed or extremely mobile, it can be extracted, and the remaining root fragment will resorb normally. For coronal third fracture in primary teeth, the coronal third is extracted, leaving the apical portion of the root to resorb normally. These root fracture cases of primary teeth were treated by resin-wire splinting despite extremely mobile coronal fragment. Even though they seems like healing well, They need to be monitored regularly until their successors erupt.

• The Journal of the Korean dental association
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• v.54 no.4
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• pp.296-305
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• 2016

Narrow zone of attached gingiva and shallow vestibule around the implants might contribute to difficulty of cleasing, periimplant mucositis caused by incomplete cleansing and further peri-implantitis. The aim of this case report is to present modification of soft tissue biotype around the implants by free gingival grafts according to timing of surgical intervention and shape of free gingiva. A 44 year-old male patient had a missing area on lower right second molar area with 1 to 2 mm of narrow attached gingiva zone and wanted to be treated by implant placement. In radiographic analysis, there was enough alveolar bone to install an implant, free gingiva from hard palate was grafted following implant placement using double layer flap. The width of attached gingival was increased to 4 to 5mm and well maintained during 5 months of follow up. A 69 year-old female patient also had a missing area on lower right first and second molar area with 1 to 2 mm narrow attached gingiva. Since she had systematically angina pectoris and dental phobia, minimal invasive free gingival graft after implants placement was planned. After 2 months of implant surgery, free gingival graft surgery was performed with healing abutments connection. The grafted gingiva was composed of two strip shaped free gingiva, and they were immobilized by periodontal pack. The width of attached gingival was increased to 4 to 5mm and well maintained during 10 months of follow up. With prosthesis delivery, the patients recovered ideal periodontal environment around implants and masticatory function. In conclusion, periodontal health and masticatory function could be achieved through implant placement and free gingival graft.

• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.47-56
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• 2008

This is a research for thickness change of denture base according to the shape of sprue & investment position of denture base in flask when injecting polyamid base resin for flexible partial denture as a part of study for Valplast among the flexible partial denture with a nylon base. It has been introduced several kinds of flexible partial denture product with a nylon base, but Valplast is the most widely used product among them. Valplast has been the most generally used material today since developed in 1950s in the United States as a material for flexible partial denture. Valplast is much more aesthetic than general metal-acrylic partial denture due to its translucent pink color and biocompatibility in terms of material characteristic. It keeps its flexibility for a long time after production, imposes a less burden on the teeth used as abutment, and it can be easily insert and remove due to its particular suppleness. Moreover, it is felt like real teeth more than metal-acrylic partial denture when being put in and takes alveolar bone under good protection since it receives occlusal force equally under the denture base. The most outstanding feature of Valplast is flexibility. The extent of its flexibility is determined by width & thickness of denture base. Considering general working procedure of Valplast, it can be seen that the thickness of denture base formed out of wax is increasing by the pressure while injecting resin. This research is to decide and test on the thickness increasing of Valplast by injecting pressure and the hypothesis upon that and is to prepare the basis estimating the increasing extent of thickness of denture base on the basis of the test result. In this test, it is expected occlusal malposition & thickness increasing of denture base by injecting pressure according to 4 kinds of test data which are to select 3 types of sprue method settling the forefront position at which the test material of fixed standard can be invested and to position the test material at the rearmost part keeping the minimum distance to set sprue. For 4 kinds of injecting test by investment position & sprue type, 20 test materials, 5 for each test were produced and a pressure of 1,180Kg was given with automatic injector of air cylinder type. The results are as follows: 1. For the amount of thickness increasing of denture base by investment position, the thickness of front investment is less increasing than the one of rear investment. 2. For the amount of thickness increasing of denture base by sprue type, the thickness of straight decompression sprue type which can absorb the injecting pressure after injecting polyamide base resin is less increasing than the other sprue types.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.63-94
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• 1990

The purpose of this study was to analyze the displacement and the magnitude and the mode of distribution of the stresses in the lower overdenture, the mucous membrane, the abutment tooth and the mandibular supporting bone when various denture base materials, such as acrylic resin and 0.5mm metal base, and various denture base designs were subjected to different loading schemes. For this study, the two-dimensional finite element method was used. Mandibular arch models, with only canine remaining, were fabricated. In the first denture base design, a space, approximately 1mm thick, was prepared between the denture and the dome abutment. In the second denture base design, contact between the denture and the dome abutment was eliminated except the contact of the occlusal third of the abutment. In order to represent the same physiological condition as the fixed areas of the mandible under loading schemes, the eight nodes which lie at the mandibular angle region, the coronoid process and the mandibular condyle were assumed to be fixed. Each model was loaded with a magnitude of 10 kgs on the first molar region(P1) and 7 kgs on the central incisal region (P2) in a vertical direction. Then the force of 10 kgs was applied distributively from the first premolar to the second molar of each model in a vertical direction(P3). The results were as follows. : 1. When the testing vertical loads were given to the selected points of the overdenture, the overdenture showed the rotatory phenomenon, as well as sinking and the displacements of alveolar ridge, abutment and lower border of mandible under the metal base overdenture were less than those under the acrylic resin overdenture. 2. The maximum principal stresses(the maximum tensile stresses) being considered, high tensile stresses occured at the buccal shelf area, the posterior region of the ridge crest and the anterior border region of the mandibular ramus. 3. The minimum principal stresses(the maximum compressive stresses) being considered, high compressive stresses occured at the inferior and posterior border region of the mandible, the mandibular angle and the posterior border region of the mandibular ramus. 4. The vertical load on the central incisal region(P2) produced higher equivalent stress in the mandible than that on any other region(P1, P3) because of the long lever arm distance from the fixed points to the loading point. 5. Higher equivalent stresses were distributed throughout the metal base overdenture than the resin base overdenture under the same loading condition. 6. The case of occlusal third contact of the abutment to the denture produced higher equivalent stresses in the abutment, the mandibular area around the abutment and the overdenture than the case of a 1mm space between the denture and the abutment. 7. Without regard to overdenture base materials and designs, the amounts and distribution patterns of equivalent stresses under the same loading condition were similar in the mucous membrane.