• Journal of Computational Design and Engineering
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• 제2권2호
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• pp.79-87
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• 2015

Surface segmentation and edge feature lines extraction from fractured fragments of relics are essential steps for computer assisted restoration of fragmented relics. As these fragments were heavily eroded, it is a challenging work to segment surface and extract edge feature lines. This paper presents a novel method to segment surface and extract edge feature lines from triangular meshes of irregular fractured fragments. Firstly, a rough surface segmentation is accomplished by using a clustering algorithm based on the vertex normal vector. Secondly, in order to differentiate between original and fracture faces, a novel integral invariant is introduced to compute the surface roughness. Thirdly, an accurate surface segmentation is implemented by merging faces based on face normal vector and roughness. Finally, edge feature lines are extracted based on the surface segmentation. Some experiments are made and analyzed, and the results show that our method can achieve surface segmentation and edge extraction effectively.

• 구강회복응용과학지
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• 제31권1호
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• pp.60-66
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• 2015

임플란트 수복물의 기계적 실패 요인들 중 가장 잦은 빈도를 보이는 것은 지대주 나사의 풀림이나 파절로 알려져 있다. 이렇게 지대주나, 나사가 파절된 경우 그 잔사들을 임플란트 고정체의 손상 없이 완전히 제거해야만 한다. 때로는 잔사들을 제거할 수 없는 경우나 제거 과정에서 고정체와 나사를 연결하는 부위가 손상되어 임플란트를 지속하여 사용할 수 없는 경우가 발생하여 임상가를 곤란하게 만드는 경우가 있다. 본 증례보고에서는 각기 다른 세가지 임상상황에서 임플란트 고정체의 손상 없이 성공적으로 파절편을 제거한 사례들을 보고하고 나사가 파절된 임상상황에서 대처할 수 있는 방법들에 대해 고찰해 보고자 한다.

• Journal of Korean Neurosurgical Society
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• 제29권5호
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• pp.668-674
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• 2000

Objective : The classic and accepted surgical method of compound comminuted depressed skull fractures (FCCD) involves total resection of all the contaminated bone and fragments at the fracture site. A second operation for cranioplasty is then performed at a later date. However, we have believed that primary repair of these bony defects can be achieved by the replacement of bone fragments at the time of the initial debridement, and this can be accomplished without danger to patient. The authors retrospectively reviewed the surgical results to assess the advantages and disadvantages, and also propose the selection criteria of replacement of fractured bone fragments as a primary procedure in FCCD. Materials and Methods : The authors analyzed the data extracted from medical records, and radiological findings in 22 of 71 patients with FCCD, who underwent immediate replacement of fractured bone fragments between April 1993 and October 1998. The mean follow-up period was 13.7 months. The selection criteria for the operation included the patients with mild to moderate severity, regardless of the degree of contamination or dural violation, which presented in hospital within 24 hours of injury. Results : The ages of the patients varied from 4 to 63 years, and there were 20 males and 2 females. Seventeen of 22 patients were fully conscious on admission and the others also had relatively good Glasgow coma scales. Sixteen fractures were located in the frontal area, 9 with involvement of the frontal sinuses, and 6 in the parietal and temporoparietal areas. Of the 22 patients, 8(36.3%) had dural lacerations with 3 of these requiring patching with pericranium, and 12(54.5%) had intracranial hematoma requiring wide craniotomy. The degree of wound contamination was also variable. Fifteen patients had relatively clean wounds, while seven(31.8%) had seriously contaminated wounds with soil, sand, hair, and wood. Only one patient(4.5%) developed infection, and the bone fragments were removed. All wounds healed primarily without pulsatile defect, the skull has remained solid, and no complications have occurred, except the infected case. Conclusion : It is proposed that bone fragments removal for FCCD, regardless of the degree of contamination or dural violation, is not necessary and that primary bone fragments replacement avoids a second operation for cranioplasty.

• 대한두개안면성형외과학회지
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• 제12권1호
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• pp.33-36
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• 2011

Background: In a frontal sinus reconstruction, the literature primarily recommends a surgical approach for definite treatment with the exception of for anterior wall fractures with no dislocation. Many studies have assessed a range of methods for the reduction of frontal sinus fractures. This paper presents a case, in whom the anterior wall of the frontal sinus was reconstructed using an outer table calvarial bone graft in an en bloc manner. Patient and methods: A 36-year-old male visited the emergency room with a heavy injury to the forehead. He was diagnosed with fractures of the anterior and posterior wall of the frontal sinus. The neurosurgeon removed the fractured area and repaired the meninges. Afterwards, cranialization was performed and the opening of the nasofrontal duct was obstructed. After fixing the removed bone to its original location, all fragments of fractured anterior wall were purged out and the anterior wall reconstructed using an en bloc calvarial bone graft. Results: In the post-operative 8 months period, there were no complications, the round contour of the forehead was expressed well and the patient was satisfied with the result. Conclusion: There are many methods for reconstructing the anterior wall of the frontal sinus. On the other hand, in cases of large fracture sites with many fractured bone fragments, en bloc harvesting of the outer table calvarial bone could be a better choice than making use of only plates and screws because this method shows a good results in terms of aesthetics with a low complication rate.

• 대한소아치과학회지
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• 제36권1호
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• pp.126-132
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• 2009

외상에 의한 영구치의 손상은 소아와 청소년기에 많이 발생하며, 특히 상악 중절치가 가장 많이 손상을 받는 것으로 알려져 있다. 그 중 치관 파절은 영구치열에서 25-76%의 빈도로 나타나며, 이러한 치관 파절시 심미적, 기능적으로 만족스러운 수복을 하기 위한 다양한 노력이 시도되어 왔다. 성인에서 영구 전치 치관 파절이 발생한 경우에는 도재 소부 전장관, 라미네이트 등의 보철적 치료로 심미적인 수복이 가능하지만, 미성숙 영구 전치의 파절이 발생한 경우에는 치근 성장이 완료되지 않아 보철적 치료가 힘들고, 근관 치료가 필요한 경우 근관 치료를 완료하는데도 오랜 시간이 소요된다. 따라서 이러한 경우 과거에는 교정용 밴드, 기성 금속관, 글래스 아이어노머 시멘트 등을 이용한 수복이 시행되었는데, 심미적으로는 만족스러운 결과를 얻지 못하였다. 그러나 근래에는 수복 치과재료의 발달로 파절편을 재부착하거나, 광중합 복합 레진 수복을 통해 심미적 수복이 가능하게 되었다. 본 증례들은 경북대학교 치과병원 소아치과에 외상에 의한 상악 중절치 파절을 주소로 내원한 환아들로, 적절한 치수 처치 후, 치아 파절편 부착과 복합 레진 수복을 통해 심미적으로 양호한 결과를 얻었기에 이를 보고하고자 한다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제21권3호
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• pp.312-316
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• 1999

When the external force was applied to the orbit the most thin area might be displaced. These were usually orbital floor and/or medial wall of orbit. Among these cases some who showed the entrapment of the muscle between the fractured fragments needed the surgical treatment. We had operated 4 cases of the "blow-out" fracture via subciliary approach. The entrapped muscles were freed from fragments and the bony defect was restored with micro-titanium mesh. Mean follow-up periods was 15 months and there were no complication observed.

• 대한치과의사협회지
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• 제54권8호
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• pp.640-650
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• 2016

Nickel-Titanium (NiTi) rotary instruments have brought a big step toward "efficient" practice of endodontic procedure. The rotary files help clinicians to reduce their working time and also increase the clinical success rate with minimal procedural errors. However, NiTi instruments still have a few drawbacks including unpredictable fatigue fracture. Clinicians may reduce the potential risk of instruments fracture by following some clinical guidelines for rotary instruments. In some clinical cases of instruments fracture, we may try to remove the instruments' fragments or bypass the fragment to reach the apical canal. In some limited cases, the fractured instruments' fragments would not jeopardize the clinical prognosis of root canal treatment. Nevertheless, it is impossible to be overemphasized that the prevention of file fracture is much easier than the removal of fracture fragment. Clinicians need to understand the fracture mechanisms and, in clinic, need to discard the used instruments timely.

• 대한치과의사협회지
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• 제52권2호
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• pp.60-68
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• 2014

Nickel-Titanium(NiTi) rotary instruments have brought a big step toward "efficient" practice of endodontic procedure. The rotary files help clinicians to reduce their working time and also increase the clinical success rate with minimal procedural errors by stainless steel instruments. In spite of these advantages, NiTi instruments still have a few drawbacks including unpredictable fatigue fracture. Clinicians may reduce the potential risk of instruments fracture by following some clinical guidelines for rotary instruments. In some clinical cases of instruments fracture, we may try to remove the instruments' fragments or bypass the fragment to reach the apical canal. In some limited cases, the fractured instruments' fragments would not jeopardize the clinical prognosis of root canal treatment. However, it is impossible to be overemphasized that the fragment removal is more difficult than the prevention of fracture. Clinicians need to understand the fracture mechanisms and, in clinic, need to discard the used instruments timely.

• 대한두개안면성형외과학회지
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• 제20권4호
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• pp.219-222
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• 2019

The purpose of this study is to discuss several approaches to addressing naso-orbito-ethmoidal (NOE) fracture. Orbital fracture, especially infraorbital fracture, can be treated through the transconjunctival approach easily. However, in more severe cases, for example, fracture extending to the medial orbital wall or zygomatico-frontal suture line, only transconjunctival incision is insufficient to secure good surgical field. And, it also has risk of tearing the conjunctiva, which could injure the lacrimal duct. Also, in most complex types of facial fracture such as NOE fracture or panfacial fracture, destruction of the structure often occurs, for example, trap-door deformity; a fracture of orbital floor where the inferiorly displaced blowout facture recoils to its original position, or vertical folding deformity; fractured fragments are displaced under the other fragments, causing multiple-packed layers of bone.

• 대한치과보철학회지
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• 제29권1호
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• pp.255-264
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• 1991

The purpose of this study was to evaluate the effect of the shear bond strength between porcelain laminate veneer and enamel according to the surface treatment and thermocycling. Group I, as a control group, was sandblasted only; group II was sandblasted and etched; group III was sandblasted and silane treated; and group IV was sandblasted, etched and silane treated. A porcelain block was placed onto the etched enamel under a 150g static load and the bonded site was light-cured from 4 directions for 1 minute each. The 72 bonded specimens were stored in water at $37^{\circ}C$ for 1 day. Half of each group were thermocycled at $4^{\circ}C$ and $60^{\circ}C$ for 100 cycles with a dwelling time in each bath of 1 min. Following thermocycling, the specimens were installed in an Instron universal testing machine and the shear bond strength was measured. After the specimens were fractured, the fractured surfaces were examined with SEM. The obtained results were as follows : 1. The shear bond strength of the sandblasted and etched and silane treated group(Group IV) was the strongest of all, and the shear bond strengths between the sandblasted group(Group I) and the sandblasted and silane treated group(Group III) were not statistically different(p>0.05). 2. When the shear bond strength was measured after thermocycling, only the sandblasted, etched and silane treated group(Group IV) was statistically different(p<0.05). 3. The scanning electron microscopic views of the fractured surfaces show more irregularities and more resin fragments in the etched group than in the unetched group. 4. The scanning electron microscopic views of the fractured surfaces show a more delicate surface after thermocycling and after silane treatment than before thermocycling and before silane treatment.