• The korean journal of orthodontics
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• v.35 no.4 s.111
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• pp.302-311
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• 2005

This study was performed to compare the fatigue limit of stainless steel wires and Fiber-reinforced composites (FRC) under conditions of permitting physiologic tooth movement. and to evaluate the clinical value of FRCs which was used to reinforce the anchorage unit. The stainless steel wire groups were divided into round and rectangular wire groups. The FRC groups were divided into uni-directional and woven groups, with resin coating and without resin coating in the Proximal area After the number of cycles to failure of each of the 6 groups were measured within the $5{\times}10^5\;cycle$ fatigue limit simulating the orthodontic treatment period. the fatigue limit of each group was compared with each other The findings of this study were as follows. In stainless steel wires, the fatigue limit of rectangular wires were higher than that of round wires. But there was no statistically significant difference (p>0.05). In FRCs with resin coating and without resin coating in the interproximal area, the fatigue limit of uni-directional type was higher than that of the woven type (p<0.05). In uni-directional and woven type FRCs, the fatigue limit of FRC with resin coating in the interproximal area was higher thar that of FRC without resin coating (P<0.05) As the FRCs and stainless steel wires did not fracture until the $5{\times}10^5\;cycle$ fatigue limit which clinically is useful. it is sufficient to use FRC and stainless steel wire for reinforcing anchorage. When esthetics is important and the attachment of additional devices are necessary. it seems sufficient to use FRC as anchorage reinforcement.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.70-81
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• 2009

Statement of problem: The position and length of cantilever influence on the stress distribution of implants, superstructure and bone. In edentulous mandible, implant-supported cantilever prostheses that based 4 or 6 implants between mental foramens has been attempted. Excessive bite force loaded at cantilever prosthesis causes bone resorption and breakage of superstructure prosthesis around posterior implants. To complement the cantilever length of conventional prosthesis, In 1992, (McCartney) introduced "cantilever-rest-implant" and Malo reported "All-on-Four" in 2003. Purpose: Analyze and compare the stress distribution of conventional cantilever prostheses with rest implant and All-on-$Four^{TM}$ implant prostheses. Material and method: The external loads(300 N vertically, 75 N horizontally) are applied to first molar area. The stress value, stress distribution and aspect of stress dispersion are analyzed by three-dimensional finite element analysis program, ANSYS ver. 10.0. Results: 1. The rest implant and "All-on-Four" implant system are superior to conventional cantilever prostheses to reduce stress on the bone and the superstructure around implants. 2. The rest implant was of the greatest advantage to stress distribution on bone, implant and superstructure. 3. With same number of implants, distally tilted implants are preferred to conventional cantilever prostheses for reducing the length of cantilever.

• Restorative Dentistry and Endodontics
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• v.30 no.4
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• pp.294-302
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• 2005

The purpose of this study was to evaluate the canal configuration after shaping by ProFile. ProTaper and K-Flexofile in simulated resin canals with different angles of curvature. Three types of instruments were used: ProFile. ProTaper. K-Flexofile. Simulated root canals. which were made of epoxy resin. were prepared by ProFile. ProTaper with rotary instrument using a crown-down pressureless technique. and hand instrumentation was performed by K-Flexofile using a step-back technique. All simulated. canals were prepared up to size 25 file at end-point of preparation. Pre and post instrumentation images were recorded with Scanner. Assessment of canal shape was completed with Image Analysis program. Measurements were made at 1. 2. 3. 4. 5. 6. 7. 8. 9 and 10mm from the apex. At each level. outer canal width. inner canal width. total canal width. and amount of transportation from original axis were recorded. Instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA analysis of variance and the Sheffe's test. The result was that ProFile and ProTaper maintain original canal shape regardless of the increase of angle of curvature than K-Flexofile. ProFile show significantly less canal transportation and maintained original canal shape better than ProTaper.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.3
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• pp.253-264
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• 2010

The purpose of this study is to know whether Yttrium-stabilized-tetragonal -zirconia-polycrystal(Y-TZP ceramic) gets enough shear bond strength for clinical uses by applying veneering composite resin through surface treatment on it and finally to compare it with the case of applying veneering porcelain. LavaTM zirconia frameworks(3M ESPE, Seefeld, Germany) were prepared. Group P was manufactured with LavaTM Ceram(3M ESPE, Seefeld, Germany) in cylindrical shape which has 4mm diameter, 5mm height. Group ZSR disposed sandblasting and applied silane, bonding agent and after that indirect composite resin was applied. Group ZRR got tribochemical coating by RocatecTM system(3M ESPE. Seefeld, Germany) and treated silane. Finally Group ZPR took the same treatment and applied LavaTM Ceram in the size of 0.3-0.5mm height. After burning out, sandblasting, HF and silane was applied. And then, indirect composite resin was applied. 1000 cycle thermocycling was performed in $5-55^{\circ}C$ and shear bond strength was measured. There were no significant differences between combining veneering porcelain to Y-TZP ceramic group and combining veneering resin to Y-TZP ceramic group in the aspect of shear bond strength (p>.05).

• Radiation Oncology Journal
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• v.16 no.1
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• pp.17-25
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• 1998

Purpose : Although local recurrence rates of stomach cancer after radiocal surgery have been reported in the range of $30-70\%$, the role of postoperative adjuvant therapy has not been established. We report the result of radiotherapy in resected stomach cancer with positive surgical margin to elucidate the role of postoperative radiotherapy. Materials and Methods : From June 1991 to August 1996, twenty five patients with positive surgical margins after radical gastrectomy were treated with postoperative radiotherapy and chemotherapy. Median dose of radiation was 55.8Gy and the range was 44.6-59.4Gy. Second cycle of chemotherapy was delivered concurrently with radiation and total number of six cycles were delivered. Twenty three had adenocarcinoma and the other two had leiornyosarcoma. The numbers of patients with stage I B, II, III A, III B, and IV were 1, 2, 11, 10 and 1 respectively. Positive margins at distal end of the stomach were in 17 patients and proximal in 5. The other three patients had positive margin at the sites of adjacent organ invasion Minimum and median follow-up periods were 12 months and 18 months, respectively, Results : Twenty-four of 25 patients received prescribed radiation dose and RTOG grade 3 toxicity of UGI tract was observed in 3, all of which were weight loss more than $15\%$ of their pretreatment weight. But hematemesis. melena, intestinal obstruction or grade 4 toxicity were not found. Locoregional failure within the radiation field was observed in 7 patients, and distant metastasis in 10 patients. Sites of locoregional recurrences involve anastomosis/remnant stomach in 3, tumor bed/duodenal stump in 3, regional lymph node in 1 patient Peritoneal seeding occurred in 6, liver metastases months and median disease free survival time was 26 months. Stages andradiation dose were not significant prognostic factors for locoregional in 2, and distant nodes in 2 patients. Four year disease specificsurvival rate was $40\%$ and disease free survival was $48\%$. Median survival was 35 failures. Conculsion : Although all patients in this study had positive surgical margins, locoregional failure rate was $28\%$, and 4 year disease specific survival rate was $40\%$. Considering small number of patients and relatively short follow-up period, it is not certain that postoperative radiotherapy lowered locoregional recurrences. but we could find a Possibility of the role of postoperative radiotherapy in Patients with high risk factors.

• Journal of dental hygiene science
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• v.12 no.4
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• pp.310-319
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• 2012

In this study, 1,495 cases of computerized data collected as disease entities of oral and maxillofacial injuries among patient visiting S university hospital located in Seoul in 2009 were analyzed and following results were obtained. It was found that the injury incidence in male was greater than in female (1.49:1), it occurred most frequently in the age of 7~14 years old (19.6%), and its most frequent cause was falling down (25.9%). Injuries occurred in other place including beach and open-air (24.7%) most frequently, often developed in anterior teeth (43.2%) and posterior teeth (43.1%), their incidence was relatively higher between 15:00~17:00 (10.4%) and 19:00~23:00 (7.1%) O'clock. In the relationship between causes of the injury and the diagnosis based on the international classification of disease), falling, fall, impingement, violence, traffic accident, sports and own making accident caused most frequently lip and oral open injuries (S01.5), open fracture of tooth (S02.51), close fracture of tooth (S02.50), close fracture of mandible (S02.60), close fracture of tooth (S02.50), respectively. From the above results, it is necessary to understand general characteristics of oral and maxillofacial injuries and to consider their trends for the establishment of systematic complement policies and for the performing safety training and public relations activities.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.212-217
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• 2017

In case of the insufficient horizontal bone loss, a regular diameter implant is not possible without lateral bone augmentation. In this situation, narrow diameter implants (NDIs) could be the alternative to lateral bone augmentation procedures. However, complication generally expected with the NDI is implant fracture. Recently, the survival rate and success rate of NDI in the posterior region are similar to that of standard-diameter implants (SDIs). These 3 case reports demonstrate the incorporation of NDI to replace missing mandibular posterior teeth. So far, the follow-up examination period was maintained and no unusual complications were presented for more than four years. Long term follow-up clinical data are needed to confirm the excellent clinical performance of these implants.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.28 no.2
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• pp.64-73
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• 2019

Various techniques have been developed, and the development of piezo electric devices have made it possible to widen the alveolar ridge even if the residual bone is dense or if there is a lack of cancellous bone between the cortical bones. In the operation of the mandibular posterior area, the flap is easily accessible to the ramus bone, from which high quality autogenous bone can be obtained, compared to other parts. A small autologous bone block can be used with particulated bone graft material using one screw for bone regeneration instead of a large autologous bone with two screws. The tapered implant design can minimize buccal bone fracture, even in severely atrophic mandibular areas. We report a case of 4 years following implant placement with ridge splitting and small autogenous bone graft in severly atrophic mandible. This report demonstrates a case of functional and aesthetic restoration in a patient through a collaboration.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.2
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• pp.127-132
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• 2013

Traumatic injuries to immature permanent teeth are common and the results can be destructive. Although Hertwig's epithelial root sheath is usually sensitive to trauma, it may resist damage from trauma thereby retaining its vitality and continuing to calcify a root under favorable conditions. This case report describes two cases of trauma to immature permanent incisors. The first case presents an avulsed maxillary central incisor which has been replanted. The other case shows completely avulsed mandibular central incisors which have not been replanted. However, both cases subsequently show continued growing roots separated from the main roots. This report highlights the ability of the immature pulp tissue to continue to form dentin and the robustness of Hertwig's epithelial root sheath to initiate root development despite a traumatic injury.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.107-115
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• 2021

Excessive pathological attrition over the entire dentition can cause decreased masticatory function, and pathological problems of the temporomandibular joint and the muscular nervous system. In this case, 71 year-old male patient with severe attrition and fracture across the entire tooth was treated by full mouth rehabilitation for regaining space of restoration. In order to determine the appropriate vertical dimension of the patient's occlusion, facial appearance, aesthetics, restoration space were evaluated, and provisional restoration of the raised vertical dimension was made. After 4 months of evaluation, the entire restoration of monolithic zirconia crown using CAD-CAM was completed. Through the above process, satisfactory aesthetic and functional results were obtained.