• Journal of Periodontal and Implant Science
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• 제35권3호
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• pp.563-575
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• 2005

The aim of present study is to evaluate the influence of adjacent tooth to the microbiology of clinically healthy implant. Control group included patients who had clinically healthy implant and tooth with healthy $periodontium(PD{\leq}3mm)$, test group was composed of patients who had clinically healthy implant and tooth with periodontal pocket(PD>3mm). The criteria of clinically health implant are no pain or discomfort, the restorative suprastructure provide satisfactory fit and function, and the tissue around the fixtures were firm and probing with standard periodontal probe with a rounded tip 0.5mm in diameter resulted in penetration of no more than 5mm when using a force of 0.5N at any location. 38 patients, partially edentulous subjects with endosseous root-form implants were selected. All subjects were medically healthy and had not taken systemic antibiotics and professional plaque control 3 months before sampling. Number of control group is 25(mean age $52{\pm}13$, 26 teeth, 34 implants) and test group is 13(mean age $60{\pm}13$, 13 teeth, 17 implants). All teeth and implants of each patient were examined probing depth(PD), bleeding on probing(BOP), and plaque index(PI), and samples of subgingival plaque were obtained at each site with sterile curet or fine paper points, then the plaque transferred to PBS. Obtained samples were examined for the presence of P. gingivalis, T. forsythensis, and T. denticola by the polymerase chain reaction(PCR). The relationship among clinical parameters and the colonizations by the 3 bacterial species from natural teeth and implants region were analyzed by student t-test. The results of this study were as follows: 1. PD was different in teeth between 2 groups(p<0.05), but the other parameters were not. 2. Statistically significant difference was not found in clinical parameters of implants between 2 groups. 3. All bacterial prevalences of teeth were higher in test group than in control group, and prevalence of T. forsythensis had statistically significant difference between 2 groups(p<0.05). 4. Prevalences of P. gingivalis and T. forsythensis are higher in test group than control group, and that of T. denticola is higher in control group than in test group. But there were no statistically significant differences between 2 groups. In conclusion, there is no statistically significant difference in prevalence of implant microbiology between 2 groups. But if the number of samples increased, it will be possible to find out statistical significance in prevalence of P. gingivalis. It seems that pocket of adjacent tooth influences prevalence of P. gingivalis. These results mean that improvement of the periodontal condition before implantation is very important.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제41권1호
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• pp.30-36
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• 2015

Objectives: The aim of this study is to determine the incidence, location, and orientation of maxillary sinus septa in formalin embalmed cadavers. Materials and Methods: The study was conducted on 210 cadaveric heads available in our department. After taking the mid-sagittal section the specimens were opened from the medial aspect and the sinus sinus septa, their anatomical plane, location and dimensions. Results: The mean linear distance between maxillary sinus floor and its anatomical ostium was $26.76{\pm}5.21mm$ and $26.91{\pm}4.96mm$ on right and left side, respectively. A total of 59 maxillary sinus septa (28.1%) were observed in 210 maxillary specimens. Septae were most common, 33 septa (55.9%), in the middle region (between first and second molar tooth) of the sinus cavity. The maxillary sinus membrane (Schneiderian membrane) adhered tightly to the maxillary sinus and over the septae. Significantly more maxillary sinus septa were observed in edentulous maxillae in comparison to the dentate upper jaw. Conclusion: Knowledge of location of maxillary sinus ostium is mandatory for the rhinologist for drainage of secretions in maxillary sinusitis. The morphological details of maxillary sinus septa, particularly their location and anatomical planes, will guide dentists in performance of safe implant surgeries. The maxillary antrum septa of category I and II may complicate the procedure of inversion of bone plate and elevation of sinus membrane during maxillary augmentation surgeries. The category III septa observed in the sagittal plane were embedded by one of the branches of the infraorbital nerve in it, and if accidentally cut will lead to infraorbital nerve palsy in maxillary sinus surgeries.

• 대한안전경영과학회지
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• 제17권2호
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• pp.129-137
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• 2015

This study is in regard to the gas detection system and gas detection method utilizing smart phone. This study includes; 1) the sensor module attached to the smart phone to detect and measure flammable gas or toxic gas; and 2) gas detection APP which is installed inside the smart phone and recognizes the user information and location information automatically by reading RFID tag indicating the user or the location to detect gas through the contact area where RFID and blue tooth reader is installed inside of the above mentioned smart phone, and then measures the combustible gas or toxic gas by operating above mentioned sensor module and obtains the data thus measured, and above mentioned smart phone is characterized by its transmission of the above mentioned user information, location information and measured data which are obtained by above mentioned gas detecting APP to operation server via communication network. With this, reliability for the location detecting gas by the user, the result of the measurement, etc. can be secured. Furthermore, this provides the effect of preventing artificial manipulation at the time of input which is associated with the identification of the user to be measured by utilizing removable sensor module and application or the mistake resulted from wrong input by the user. In addition, by transmitting the measured data from the sensor module carrying out gas detection to operation server, this provides the effect of making it possible to process the data thus collected to a specialized data for combustible gas or toxic gas.

• 대한치과보철학회지
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• 제54권1호
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• pp.14-20
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• 2016

목적: 본 연구의 목적은 임플란트와 대합되는 부분의 상태에 따라서 임플란트 주위 골조직 변화에 차이가 있는지 알아보기 위함이다. 대상 및 방법: 원광대학교 대전치과병원에서 임플란트 식립을 받은 51명의 환자를 대상으로 하였고 총 51개의 임플란트가 분석에 사용되었다. 임플란트는 성별, 나이, 악골 위치, 환자의 대합되는 부위에 따라서 분류되었고 대합되는 부위는 자연치, 임플란트, 가공치, 무치악의 네 집단으로 나뉘었다. 프랙탈 분석을 위해 임플란트 식립 직후의 치근단 사진과 보철 수복 이후 10주 이상이 지난 치근단 사진이 사용되었다. 분석은 Image J를 이용하여 시행하였다. 통계학적 분석은 one-way ANOVA를 이용하여 시행하였고 Tukey multiple comparison test로 사후검정을 실시하였다. 결과: 임플란트의 보철수복 전후 프랙탈 값 차이의 평균은 자연치가 대합되는 경우 $0.009{\pm}0.048$이었으며 임플란트의 경우 $0.026{\pm}0.080$, 가공치의 경우에 $-0.025{\pm}0.068$이었으며 무치악은 $-0.093{\pm}0.171$으로 나타났다. 대합되는 부위가 무치악일 때와 임플란트일 때에 통계학적으로 유의한 차이가 나타났으며 나이와 성별, 악골 위치에 따른 프랙탈 수치 변화 차이는 통계적으로 유의하지 않았다. 결론: 임플란트 식립 후 대합되는 부위가 무치악일 때를 제외한 세 집단간 프랙탈 수치 변화 차이는 유의하게 나타나지 않았으며, 대합되는 부위가 무치악일 때와 임플란트일 때 유의한 차이가 나타났다. 그리고 환자의 나이와 성별, 악골의 위치에 따른 프랙탈 수치 변화 차이는 유의한 차이를 나타내지 않았다.

• 한국정밀공학회지
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• 제31권3호
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• pp.223-232
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• 2014

An inductive sensor system is proposed to detect the gear location and angular position of a geared shaft for automatic feeding of the shaft into the proper cutting position of the other end. The system consists of two set of coils, bridge circuit, signal condition circuit, and microprocessor. The coil sensors of the system measure changes of inductance along with the surface position of a geared shaft. The inductance changes are transformed to voltages by the bridge circuit, which are then conditioned and processed for the recognition of the gear. In order to incorporate with the experimental results with the sensor system, a finite element method (FEM) simulation for the magnetic field between the sensor and the shaft was carried out. The predicted results and the experiments revealed that the sensor system was appropriate for sensing the position of gear and the angular position of gear tooth of a geared shaft.

• 대한소아치과학회지
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• 제35권2호
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• pp.333-338
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• 2008

과잉치란 정상에 비해 많은 수의 치아를 일컫는 것으로 유치열기와 혼합치열기에 발생하며, 여러 가지 임상적 문제를 일으킬 수 있다. 특히 상악 전치부의 과잉치는 상악 전치의 맹출 장애 및 전위, 정중부의 치간 이개, 치근 흡수, 함치성낭종 형성 등의 문제를 유발할 수 있으므로 조기에 진단하고, 과잉치의 위치 및 수, 형태에 따라 적절한 치료를 시행하는 것이 중요하다. 이 증례는 상악 전치부에 네 개의 과잉치가 영구치의 맹출을 방해하고 있는 경우로, 발거 시 합병증을 최소화하기 위하여 두 단계로 나누어 발거하였다. 컴퓨터 단층 촬영에서 네 개의 과잉치가 주위의 영구치 맹출을 방해하고 있었고, 그 중 두 개의 과잉치는 절치 치배에 매우 근접해 있었다. 네 개의 과잉치를 동시에 제거할 경우 영구 치배에 손상을 줄 위험이 있으므로 두 개의 역위 매복된 원추형의 과잉치만 먼저 발거하였다. 남은 두 개의 과잉치는 위치가 변화되기를 기다린 후 두 번째 발거 수술을 시행하여, 주위 절치 치배에 손상을 가하지 않고 치조골 삭제를 적게 하여 합병증 발생을 줄일 수 있었다.

• Imaging Science in Dentistry
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• 제44권4호
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• pp.279-285
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• 2014

Purpose: To assess the influence of anatomic location on the relationship between computed tomography (CT) number and X-ray attenuation in limited and medium field-of-view (FOV) scans. Materials and Methods: Tubes containing solutions with different concentrations of $K_2HPO_4$ were placed in the tooth sockets of a human head phantom. Cone-beam computed tomography (CBCT) scans were acquired, and CT numbers of the $K_2HPO_4$ solutions were measured. The relationship between CT number and $K_2HPO_4$ concentration was examined by linear regression analyses. Then, the variation in CT number according to anatomic location was examined. Results: The relationship between $K_2HPO_4$ concentration and CT number was strongly linear. The slopes of the linear regressions for the limited FOVs were almost 2-fold lower than those for the medium FOVs. The absolute CT number differed between imaging protocols and anatomic locations. Conclusion: There is a strong linear relationship between X-ray attenuation and CT number. The specific imaging protocol and anatomic location of the object strongly influence this relationship.

• 대한치과보철학회지
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• 제34권3호
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• pp.501-532
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• 1996

This study investigated the effects of cantilever length, location and load condition on stress distribution developed in the implants, prostheses and supporting tissues. The osseointegrated prostheses with two 10mm Branemark implants at 2nd premolar and 1st molar sites with cantilever extensions at 1st premolar, 2nd and 3rd molar sites were constructed. Under 100N, 200N of vertical and $45^{\circ}$ oblique loads at the cantilever pontics, stress distribution patterns and displacement were analyzed with three dimensional finite element method. The results were as follows : 1. The stress was concentrated at the joint of the cantilever pontic and implant superstructure, the neck of implant and the ridge crest near the cantilever But there was little load transfer to the lower supporting tissues of implants. 2. The implant near the cantilever was displaced inferiorly while the implant far from the cantilever was displaced superiorly. In horizontal direction the implants were displaced to the direction where the loads were applied, except the apexes of the implants. 3. In case of anterior cantilever, the stress and displacement were higher than the prosthesis connected with natural tooth. 4. The stress developed in the posterior cantilevered type was higher than in the anterior cantilevered type. The greastest stress was concentrated at the ridge crest near the posterior cantilever. 5. The longer the cantilever, the more the stress was developed and was concentrated at the joint of the cantilever pontic and implant superstructure. 6. Under oblique load, the stress was concentrated at the necks of implants and the ridge crests, but decreased at the joint of the cantilever pontic and implant superstructure than under vertical load.

• 대한치과교정학회지
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• 제31권4호
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• pp.425-438
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• 2001

이 연구는 3차원 유한요소법을 이용하여 상악 6전치부에 피질골 절단술을 시행한 경우와 시행하지 않은 경우에서 상악 6전치부를 하나의 단위로 하여 다양한 후방견인력을 가하였을 때 상악 6전치의 초기 치아이동을 통하여 저항중심의 수직적 위치를 계측, 비교하고 저항중심의 변화양상을 관찰하며, 힘의 크기변화에 따른 저항중심의 위치변화양상을 분석하기 위하여 시행되었다. 상악 6전치와 치주인대 및 치조골의 3차원 유한요소모델을 제작한 후, 상악 6전치부에 부착된 설측장치와 이 장치가 부착된 치아군을 한 개의 견고한 연결체로 가정하였다. 유한요소모델에서 사용된 전체요소의 수는 14,584개, 전체 절점의 수는 17,292 개였고, 힘 체계의 분석을 위해 미국 Swanson Analysis System사의 범용 유한요소 프로그램 인 ANSYS(Ver. 5.5A)를 사용하였다. 저항중심은 힘이 가해질 때 치아가 평행 이동될 수 있는 힘의 적용부위라 정의하고, 설측 장치에서 연장된 Extension arm의 7개의 Level에 편측당 각각 200 gm, 250 gm, 300 gm, 350 gm의 설측 후방견인력을 가하였을 때 치아의 절단연과 치근첨에서의 변위를 읽어 평행이동이 일어나는 위치를 복원법으로 계산하여 저항중심의 위치를 계측, 분석하여 다음과 같은 결과를 얻었다. 1. 상악 6전치부의 초기치아이동에서 저항중심의 수직적 위치는 Level 4와 Level 5사이, 즉 치경부에서 치근단 쪽으로 6.76 mm, $44.32\%$ 떨어진 거리에 위치하였다. 2. 피질골 절단술 시행후, 상악 6전치부의 후방 견인시 저항중심의 수직적위치는 Level 4와 Level 5사이, 즉 치경부에서 치근단 쪽으로 7.09 mm, $46.38\%$ 떨어진 거리에 위치하였다. 3. 후방견인력의 크기가 커짐에 따라 치아의 변위량은 커졌으나, 피질골 절단술 시행 유무에 관계없이 후방견인력의 크기변화는 저항중심의 수직적 위치에 별다른 영향을 미치지 않았다. 4. 피질골 절단술 시행시에 저항 중심의 수직적 위치는 치근단 쪽으로 이동하였고, 그 변위량은 피질골 절단술 시행 시가 컸다. 이상의 결과로 볼 때 상악 6전치부 후방견인시 저항중심의 수직적 위치는 치경부에서 치근단 쪽으로 치근길이의 $44.32\%$ 떨어진 거리에 위치하였고, 피질골 절단술 시행시에 저항중심의 수직적 위치는 치경부에서 치근단 쪽으로 치근 길이의 $46.38\%$ 떨어진 거리에 위치하여 피질골 절단술 시행하지 않은 경우보다 치근단 쪽으로 이동되었으며, 후방견인력의 크기 변화에 따라 저항 중심의 수직적 위치는 변하지 않았다.

• 대한소아치과학회지
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• 제24권3호
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• pp.562-567
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• 1997

During the eruption of permanent teeth, Traumatic root fractures in young permanent incisors are rare. They occur most commonly in the maxillary central incisors of male patient and are frequently seen in the coronal third of the root. Permanent incisors are very important in terms of esthetics as well as of function, and so conservative treatment is advisable. It is important to maintain vitality of pulp to achieve better result. Location of the fracture line determines the Prognosis. No clinical change were seen in this three case. A case of central incisor with apparent healing of a root fracture without any tratment is presented in this paper. Long term clinical observation is required periodically.