• Imaging Science in Dentistry
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• 제31권3호
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• pp.165-173
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• 2001

Objectives : To evaluate the absorbed and effective doses of spiral and computed tomography for the dental implant planning. Materials and Methods: For radiographic projection, TLD chips were placed in 22 sites of humanoid phantom to record the exposure to skin and the mean absorbed dose to bone marrow, thyroid, pituitary, parotid and submandibular glands and nesophagus. Effective dose was calculated, using the method suggested by Frederiksen et al.. Patient situations of a single tooth gap in upper and lower midline region, edentulous maxilla and mandible were simulated for spiral tomography. 35 axial slices (maxilla) and 40 axial slices (mandible) with low and standard dose setting were used for computed tomography. All the radiographic procedures were repeated three times. Results: The mean effective dose in case of maxilla was 0.865 mSv, 0.452 mSv, 0.136 mSv and 0.025 mSv, in spiral tomography of complete edentulous maxilla, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). That in case of mandible was 0.614 mSv, 0.448 mSv, 0.137 mSv and 0.036 mSv, in spiral tomography of complete edentulous mandible, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). Conclusions: Based on these results, it can be concluded that low mAs computed tomography is recommended instead of spiral tomography for the complete edentulous maxilla and mandible dental implant treatment planning.

• Archives of Plastic Surgery
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• 제43권1호
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• pp.40-45
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• 2016

Background Bioabsorbable plates and screws are commonly used to reduce maxillofacial bones, particularly in pediatric patients because they degrade completely without complications after bone healing. In this study, we encountered eight cases of a delayed foreign body reaction after surgical fixation with bioabsorbable plates and screws. Methods A total of 234 patients with a maxillofacial fracture underwent surgical treatment from March 2006 to October 2013, in which rigid fixation was achieved with the Inion CPS (Inion, Tampere, Finland) plating system in 173 patients and Rapidsorb (Synthes, West Chester, PA, USA) in 61 patients. Their mean age was 35.2 years (range, 15-84 years). Most patients were stabilized with two- or three-point fixation at the frontozygomatic suture, infraorbital rim, and anterior wall of the maxilla. Results Complications occurred in eight (3.4%) of 234 patients, including palpable, fixed masses in six patients and focal swelling in two patients. The period from surgical fixation to the onset of symptoms was 9-23 months. Six patients with a mass underwent secondary surgery for mass removal. The masses contained fibrous tissue with a yellow, grainy, cloudy fluid and remnants of an incompletely degraded bioabsorbable plate and screws. Their histological findings demonstrated a foreign body reaction. Conclusions Inadequate degradation of bioabsorbable plates caused a delayed inflammatory foreign body reaction requiring secondary surgery. Therefore, it is prudent to consider the possibility of delayed complications when using bioabsorbable plates and surgeons must conduct longer and closer follow-up observations.

• Archives of Plastic Surgery
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• 제39권2호
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• pp.113-117
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• 2012

Background : Nasal pyramid fractures accompanied by saddle nose deformities are not easily corrected by closed reduction. We used an absorbable plate as a perpendicular strut to support the collapsed "keystone area" and obtained good results. Methods : Between September 2008 and June 2011, 18 patients who had nasal pyramid fractures with saddle nose deformities underwent surgery. Pre- and postoperative facial computed tomographic images and photographs were taken to estimate outcomes. The operative technique included the mucoperichondrial dissection of the nasal septum, insertion of an absorbable plate prepared to an appropriate length to support the "keystone area", and fixation of the absorbable plate strut to the cartilaginous septum. Results : Functional and esthetic outcomes were satisfactory in all patients. Eleven patients assessed the postoperative appearance of the external nose as 'markedly improved' and 7 patients as 'improved'. The 5 surgeons scored the results as a mean of 4.5 on a 5-point scale. Conclusions : The use of an absorbable plate as a perpendicular strut requires no additional procedures because the plate is gradually absorbed. The mechanical strength provided by a buttress between the "keystone area" and the maxillary crest lasts for a long time before the strut is absorbed.

• Journal of Korean Neurosurgical Society
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• 제30권12호
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• pp.1369-1374
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• 2001

Objectives : The rates of pseudarthrosis for two- and three level fusion have been reported to be 17-63 and 50% without anterior cervical plating. The purpose of this study is to assess the effects of anterior cervical plating in the treatment of multilevel degenerative cervical disease such mostly the additional risks associated with hardware implants and its benefits, fusion rate and radiographic results, and clinical outcomes. Methods : Forty-seven patients who underwent operations between 1993 and 1997 were retrospectively reviewed. The technique for operation was same for both groups(Smith Robinson with autologous iliac bone graft). Group I consisted of 35 consecutive patients treated with anterior cervical decompression and fusion with anterior cervical plate fixation. Group II consisted of 12 consecutive patients treated without plate fixation. We compared clinical outcomes by Prolo score, radiographic results in the rate of fusion, cervical lordosis by Gore angle, disc height by Farfan method, and surgical complications between two groups. Results : The favorable clinical outcomes(excellent and good) by Prolo score were observed with the use of anterior cervical plate fixation(89% vs 75%). The successful fusion rate of multilevel cervical fusion was as seen with anterior cervical plate fixation(97% vs 75%). The overall graft complication rate in multilevel fusions was decreased, with anterior cervical plate fixation, and the hardware related complications were relatively minimal without serious consequences. Conclusion : Anterior cervical plate fixation in the treatment of multilevel cervical disorders is an effective stabilizing method which provides increased bony fusion rate, decreased graft complications, maintained cervical lordosis, early mobilization of the these patients without serious hardware related complications.

• Journal of Korean Neurosurgical Society
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• 제38권2호
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• pp.96-101
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• 2005

Objective : This paper describes our experience and implant technique for cranioplasty of a large cranial defects using a porous polyethylene implant[Medpor] and compares the results with polymethylmethacrylate[PMMA]. Methods : Sixteen cranioplasties were performed using Medpor[n= 10] and PMMA[n=6] implants between June 2003 and January 2005. The criterion for patient enrollment was a defect larger than 10cm in diameter. This study compared the operation times and complications. Results : The operation times ranged from 105 to 250minutes[Mean $180^{\circ}{\pm}44minutes$) in Medpor and from 185 to 460minutes [mean 128minutes] in PMMA. The absolute operation times were shorter using the Medpor implant and the differences were statistically significant[P=0.030]. Satisfactory cosmetic results were obtained in all cases using the Medpor implant and with no implant-related complications. Bone ingrowth to the medpor implant was presumed to be the result on an increase in Houndsfield units of the implant, particularly at the marginal areas in the serial follow-up brain computed tomography images. Conclusion : It is believed that the properties of a Medpor implant make this implant an good alternative to the existing methods of a cranial contour correction. However, a further follow-up study will be needed.

• 대한치과교정학회지
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• 제42권4호
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• pp.159-168
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• 2012

Objective: The aims of this study were to investigate mandibular deformation under clenching and to estimate its effect on the stability of orthodontic mini-implants (OMI). Methods: Three finite element models were constructed using computed tomography (CT) images of 3 adults with different mandibular plane angles (A, low; B, average; and C, high). An OMI was placed between #45 and #46 in each model. Mandibular deformation under premolar and molar clenching was simulated. Comparisons were made between peri-orthodontic mini-implant compressive strain (POMI-CSTN) under clenching and orthodontic traction forces (150 g and 200 g). Results: Three models with different mandibular plane angles demonstrated different functional deformation characteristics. The compressive strains around the OMI were distributed mesiodistally rather than occlusogingivally. In model A, the maximum POMI-CSTN under clenching was observed at the mesial aspect of #46 (1,401.75 microstrain [${\mu}E$]), and similar maximum POMI-CSTN was observed under a traction force of 150 g (1,415 ${\mu}E$). Conclusions: The maximum POMI-CSTN developed by clenching failed to exceed the normally allowed compressive cortical bone strains; however, additional orthodontic traction force to the OMI may increase POMI-CSTN to compromise OMI stability.

• Journal of Periodontal and Implant Science
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• 제50권5호
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• pp.327-339
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• 2020

Purpose: The purpose of this study was to examine the local tissue reactions associated with 3 different poly(lactic-co-glycolic acid) (PLGA) prototype membranes and to compare them to the reactions associated with commercially available resorbable membranes in rats. Methods: Seven different membranes-3 synthetic PLGA prototypes (T1, T2, and T3) and 4 commercially available membranes (a PLGA membrane, a poly[lactic acid] membrane, a native collagen membrane, and a cross-linked collagen membrane)-were randomly inserted into 6 unconnected subcutaneous pouches in the backs of 42 rats. The animals were sacrificed at 4, 13, and 26 weeks. Descriptive histologic and histomorphometric assessments were performed to evaluate membrane degradation, visibility, tissue integration, tissue ingrowth, neovascularization, encapsulation, and inflammation. Means and standard deviations were calculated. Results: The histological analysis revealed complete integration and tissue ingrowth of PLGA prototype T1 at 26 weeks. In contrast, the T2 and T3 prototypes displayed slight to moderate integration and tissue ingrowth regardless of time point. The degradation patterns of the 3 synthetic prototypes were similar at 4 and 13 weeks, but differed at 26 weeks. T1 showed marked degradation at 26 weeks, whereas T2 and T3 displayed moderate degradation. Inflammatory cells were present in all 3 prototype membranes at all time points, and these membranes did not meaningfully differ from commercially available membranes with regard to the extent of inflammatory cell infiltration. Conclusions: The 3 PLGA prototypes, particularly T1, induced favorable tissue integration, exhibited a similar degradation rate to native collagen membranes, and elicited a similar inflammatory response to commercially available non-cross-linked resorbable membranes. The intensity of inflammation associated with degradable dental membranes appears to relate to their degradation kinetics, irrespective of their material composition.

• 대한심미치과학회지
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• 제24권1호
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• pp.39-48
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• 2015

전치부 임플란트의 심미성에 영향을 미치는 중요한 요소는 다음과 같다. 1) 임플란트 식립체의 올바른 위치, 2) 치조골의 충분한 양, 3) 연조직의 최적의 양. 임플란트 위치는 심미적인 치료결과를 얻는 데에 가장 중요한 요소일 것이다. 임플란트의 3차원적 위치는 치조제의 위치와 방향에 의해 결정된다. 임상가들은 수복물을 제작할 때 흔히 자연치를 모방하려 한다. 그러나 심미적인 진단 및 치료를 하는 과정에서 잊지 말아야 할 것은 얼굴형태, 입술, 치은, 치조제, 그리고 잔존치아들과의 상관관계를 고려하는 것이다. 전치부는 구치부에 비해 생물학적으로 불리하며, 조금이라도 임플란트 위치가 틀어지면 심미적으로 좋지 않은 결과를 야기할 수 있다. 임플란트 3치원적 위치의 생물학적, 보철적 의미를 이해한다면, 전치부에 더욱 심미적인 결과를 얻을 수 있을 것이다.

• 대한치과보철학회지
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• 제54권2호
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• pp.126-131
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• 2016

구강암에 의해 하악골 절제술을 받은 환자들은 저작 및 연하 기능의 저하와 같은 문제가 발생하며 동반된 안모의 변화와 발음의 문제로 인하여 사회적, 심리적인 영향을 받게 된다. 따라서 보철적인 수복을 통해 하악골 변연절제술 환자의 문제를 개선해 나아가는 것이 무엇보다 중요하다. 본 증례는 편평세포암으로 인하여 하악골 변연절제술을 받은 환자에서 골결손이 일어나지 않은 후방부위에 전략적으로 임플란트를 식립하였고 임플란트를 통해 의치의 유지와 지지를 담당할 수 있도록 보철물을 설계하였다. 이를 바탕으로 Kennedy class IV 국소의치를 제작하여 만족스런 심미적, 기능적 결과를 얻었으며, 8개월 간의 임상 관찰 동안 임플란트 주변 골의 안정적인 유지가 관찰되는 바 이를 보고하고자 한다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제29권3호
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• pp.241-249
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• 2007

An augmentation of the maxillary sinus floor facilitates placement of dental implants in the posterior atrophic maxilla. However, a maxillary sinus augmentation has potential complications that can lead to early failure and loss of the bone graft. One specific complication is sinus membrane perforation. Especially, large perforations may cause loss of the graft materials into the sinus and infection, so, early failure of the sinus lift. Attempts at managing sinus membrane perforations are difficult because of the limited access to them and friability of the thin Schneiderian membrane. Repair of sinus membrane perforations intraoperatively may be performed using a variety of techniques and materials, including sutures, collagen membranes, fibrin glue. Inspite of various repair technique, as has been reported extensively in the literature, large perforations represent an absolute contraindication to the continuation of surgery. But, we obtained clinically favorable results in cases that show repair of the perforated sinus membrane with a micro-suture technique by 4X Loupe ($Surgitel^{(R)}$ Loupe, General Scientific Corporation) in large perforation. The objective of this presentation is to report of several cases of repair of the perforated sinus membrane with micro-suture technique using 7.0 or 8.0 suture materials, to make a brief review of the literature about various technique managing perforated sinus membrane.