• 구강회복응용과학지
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• 제29권3호
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• pp.224-235
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• 2013

임플란트의 장기적인 성공을 위해 고정체의 형태, 외과적 술식, 골조직의 조건, 보철물 적합성, 주기적인 검사, 환자의 구강 위생 등에 많은 주의가 필요하다. 많은 연구에서 임플란트 지지 보철물의 적합도에 따른 임플란트의 예후에 관해 보고되었다. 보철물이 수동 적합되어야 임플란트의 상부구조및 하부구조에 해로운 응력을 야기하지 않는다고 보고되고 있으나 현재의 임플란트 보철물의 제작과정으로 진정한 수동 적합을 얻는 수 없다고 인정된다. 임상과정과 기공과정을 포함하여 임플란트 치료의 전 과정에서 오차가 발생하며, 이는 보철물을 변형을 야기하고 이는 임플란트 상부 보철물과 지대주 사이의 오차를 발생시킨다. 이러한 오차는 보철물 장착 후 보철물의 파절, 나사의 헐거움(screw loosening), 골소실, 골유착 실패와 같은 문제를 야기한다. 이런 오차에 의한 문제점은 cantilever의 존재, 과도한 교합력이 존재할 경우 더욱 증가된다고 보고되고 있다. 본 연구에서는 ITI 임플란트를 하악골의 견치후방의 무치악부에 3개를 식립하고 4-unit 캔틸레버 고정성 국소의치를 다양한 위치의 $100{\mu}m$ gap을 생성한 후 제작하고 gap을 생성하지 않은 고정성 국소의치와 30 lb의 하중하에서 광탄성 응력분석을 시행하여 응력분포 양상과상대적인 응력의 크기를 비교분석하였다.

• Journal of Periodontal and Implant Science
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• 제36권1호
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• pp.147-154
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• 2006

Surgical intervention in the posterior maxillary region requires detailed knowledge of maxillary sinus anatomy and the possible anatomical variations. This study evaluated the incidence, location of maxillary sinus septa by using radiographic (panoramic radiography and computed tomography) findings and comparison of panoramic radography with CT in antral anatomical variation. This study was based on data from 70 sinuses in partial dentate maxilla. The sample consisted of 61 patients(25 women and 36 men, with ages ranging between 19 and 77 years and a mean age of $49.4{\pm}11.3$ years) who were being treatment-planned to receive implant-supported restorations. First, the panoramic images were examined for the presence of antral septa by radiologist and examiner who don't know about CT findings. And incidence of antral septa was evaluated using an axial plane of CT image. The incidence of septa was compared between panoramic radiography and CT. The accuracy of the incidence was compared between radiologists and dentists. A total of 20 septa were found in 70 sinuses on CT image and the prevalence of one or more septa per sinus was found to be 28.6%. The assumed incidence of septa on panoramic radiography was $27.6%{\pm}2.2%$ in radiologist and $31.9%{\pm}5.8%$ in dentists. Erroneous diagnosis rate was 11.42% in radiologist and 15.96% in dentists. 40% of antral septa were located in the anterior(premolar) region, 30% of septa were located in the middle(first molar) and posterior(second molar) region separately. Prior to implant placement, it seems appropriate to consider panoramic radiography as a standard radiographic examination and periapical radiographs may be used to complete the findings in regions not sharply depicted in the panoramic radiograph. And cross-sectional imaging should be used in sites with severe bone loss and close proximity of the maxillary sinus.

• 대한치과보철학회지
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• 제39권3호
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• pp.243-249
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• 2001

Statement of the problem. The interest in all-ceramic restorations has increased as more techniques have become available. With the introduction of machinable dental ceramics and CAD/CAM systems or Copy-milling systems there is a need for evaluating the quality levels of these new fabrication techniques. Purpose. This study was to evaluate the fitting accuracy of machined all-ceramic crowns made out of an industrially prefabricated feldspathic porcelain. Material and Methods. Three master models with different cutting depth (0.8mm/1.0mm/1.2mm)were produced using a palladium-silver alloy. A total of 36 working dies, 12 of each form, was used for the modellation of prototype resin copings and 36 additional crowns, 12 of each cutting depth, were produced by using the $CEREC^{(R)}2$ system for all crowns. The maginal fit of all 72 crowns was then evaluated on their respective master die at 54 circularly staggered points of measurement per crown under a fixation pressure of 30 N by using a computerized video image system. Results. The medians of the copy-milled $CELAY^{(R)}$ crowns ranged from 29 to $36{\mu}m$. The highest value for the marginal gap was found in group B (cutting depth 1.0mm) at $107{\mu}m$. The median for the $CEREC^{(R)}2$ crowns was found between 43.5 and $70{\mu}m$. The maximum values for all three groups ranged from $181{\mu}m$ to $286{\mu}m$. With $286{\mu}m$ the highest value for marginal gap was found in group C. the Kruskal-Wallis test and multiple comparisons analysis procedure revealed a significant influence of the production technique on the marginal fit in all three groups (p<0,02). Conclusion. 1. The $CELAY^{(R)}$ system is capable to produce all-ceramic crowns with a significantly better marginal fit than the $CEREC^{(R)}2$ system. 2. As far as premolar crowns produced with the $CEREC^{(R)}2$ system are concerned, the cutting depth has a significant influence on fitting accuracy. 3. The production of crowns with an acceptable marginal fit is possible with both systems. However, adhesive luting is recommended for milled feldspathic porcelain crowns.

• 대한치과보철학회지
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• 제50권4호
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• pp.324-329
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• 2012

치아의 과도한 마모는 광범위한 치질의 상실, 교합평면의 부조화를 야기하고 기능적, 심미적 문제를 발생시킬 수 있다. 마모에 의한 수직 고경의 감소는 치조골의 보상성 성장에 의해 상쇄될 수도 있지만 보철물의 유지를 위한 치아의 길이가 부족하다면 환자에게 불편감이 없는 한에서 최소한의 수직 고경 증가를 동반한 보철적 수복이 필요하다. 본 증례는 33세 여성 환자로 하루에 콜라를 1리터 이상 마시고 밤에 심한 이갈이 습관을 가지고 있어 전악에 걸친 마모와 심미적, 기능적 불편감을 주소로 서울대학교 치과병원에 내원하였다. Erosion과 이갈이 습관으로 급속히 치아의 마모가 일어났고, 환자의 적절한 수직 고경을 결정하기 위해 안모와 발음, 심미, 기능 등을 평가한 결과 수직고경이 상실되었다고 판단되었다. 수복을 위한 5 mm의 수직고경 거상이 계획되었고 환자의 적응을 위해 임시치아의 수직고경을 각각 3 mm와 2 mm로 두번에 걸쳐 증가시켰다. 총 16주의 관찰기간 동안 임상증상과 불편감이 없음을 확인한 후, 전악을 금속도재 보철물로 수복하였다. 환자가 젊은 여성이라는 점에서 전치부는 collarless 금속도재 보철물로 수복하였다. 이상과 같은 과정을 통해 교합고경 회복을 동반한 보철 수복으로 적절한 심미적, 기능적 결과를 얻었기에 이를 보고하고자 한다.

• 대한치과보철학회지
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• 제18권1호
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• pp.15-35
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• 1980

The purpose of this study was to investigate stresses in the various components of fixed partial dentures restoring the posterior teeth of the lower jaw, and to measure quantitatively the effects of certain modifications in structural design on the stresses in the restorations using two-dimensional photoelasticity. Two-dimensional photoelastic methods were used in this study. Several models of fixed partial dentures were constructed. Shoulder less margins and anatomic occlusal reduction were incorporated in Model 1. Rounded shoulders and flat occlusal reduction were incorporated in Model 2, while Model 3 was a cantilever fixed partial denture. Other similar fixed partial dentures were constructed with V and U notches deliverately included in the region of the fixed joints for comparative reasons. The birefringent materials used in this study were PSM-1 and PSM-5 in standard sheets. PSM-1 was used for constructing the substructure, and PSM-5 was used in making the components of the fixed partial dentures. The two materials were used in the construction of composite photoelastic models. Improved artificial stone was used to represent dental cement in luting the composite photoelastic models. Static loading procedures were used at preplanned sites to represent occlusal loads in the mouth. 35 mm color and B/W film were used to record isochromatics in accordance with photoelastic procedures. Data reduction was performed using the grid method, which helped in, the mathematical integration procedure (Shear difference method) to separate the principal stresses. The results were as follows. 1. Fixed partial dentures do not function in bending as a symmetrical beam. Alternate areas of tension and compression were demonstrated when multiple contact loading was used. 2. The weakest part in posterior fixed partial dentures is the fixed joint. 3. (1) Models I and modified Model I were loaded on the pontic using a 50 pound vertical static load. The shear stress near the posterior fixed joint in Model 1 (U notches) was+129.4 p.s.i., and at the same fixed joint in modified Model 1 (V notches) was+239.4 p.s.i. The concentration of stress in fixed joint was reduced by 50% when U notches replaced the V notches. (2) Modified Model 2 was loaded using a multiple contact loader at a total load of 125 pounds. The difference between the principal stresses (${\sigma}_1-{\sigma}_2$), shear stress, at the V notches was+600 p.s.i., and at the U notches was+3l7 p.s.i. The shear stress was reduced by 50% when U notches replaced the V notches. V-grooves at the fixed joints should be avoided, and should be replaced by regular shaped U-grooves. 4. Cantilever fixed partial dentures had much higher stresses at the fixed joint than fixed partial dentures that were attached at both ends.

• 구강회복응용과학지
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• 제16권2호
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• pp.105-112
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• 2000

본 연구는 치아형성시 shoulder 폭경이 변연 적합도에 미치는 영향을 평가하기 위해 시행하였다. 지대치의 치경부쪽의 shoulder 폭경을 0.6 mm, 0.9 mm, 1.2 mm로 나누어 각각 9개씩, 총 27개의 모형을 제작하여 통법에 따라 In-Ceram 전부 도재관을 제작한 후 시멘트 접착하고 근심, 원심, 협, 설측 중앙 부위를 200배 확대하여 변연 적합도의 측정한 후 각 군과, 측정부위에 따른 변연 적합도 비교해 본 결과 다음과 같은 결론을 얻었다. 1. shoulder 폭경이 0.6 mm인 경우 $81.28{\mu}m$, 0.9 mm인 경우는 $70.78{\mu}m$, 1.2mm 인 경우는 $67.75{\mu}m$의 변연간극을 보였다. 2. shoulder 폭경이 0.6 mm인 경우가 0.9 mm, 1.2 mm인 경우보다 변연간극이 유의한 차이를 크게 나탔났으며(p<0.05), 0.9 mm인 경우와 1.2 mm인 경우는 유의한 차이가 없었다(p>0.05). 3. In-Ceram 시편의 변연부에서 근심측, 원심측, 순측, 설측의 측정위치에 따른 변연적합도의 비교시 유의한 차이가 없었다(p>0.05).

• 구강회복응용과학지
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• 제16권2호
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• pp.133-147
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• 2000

A well-planned, precise occlusal adjustment of natural teeth has some distinct advantages over other forms of occlusal therapy. It should be emphasized, however, that an occlusal adjustment is an irreversible procedure and has definite contraindications in some mouths. Generally, the treatment methods for the patients that has open-bite will be following as below. : (1) Use of removable orthopedic repositioning appliance, (2) Orthodontics, (3) Full or partial reconstruction of the dentition, (4) Orthognathic surgical procedure, (5) Occlusal adjustment of the existing natural teeth, (6) Any combination of the above. Above all, the advantages of occlusal adjustment of natural teeth are : (1) the patient is more able to adapt to the changes in jaw position and posture; (2) the phonetic or speaking ability of the patient is not significantly changed and usually is improved; (3) the esthetics of the natural teeth is not altered and often is better; (4) the hygiene of the individual teeth is easily maintained; and (5) the functional usage of the teeth as cutting and chewing devices is markedly improved. The objective of an occlusal adjustment, as with any form of occlusal therapy, is to correct or remove the occlusal interferences, or premature contacts, on the occluding parts of the teeth which prevent a centric relation closure of the mandible. A systematic, disciplined approach can be followed in treatment, the objectives should be listed. They are : (1) Centric relation occlusion of the posterior teeth. (2) Proper "coupling" of the anterior teeth. (3) An acceptable disclusive angle of the anterior teeth in harmony with the condylar movement patterns. (4) Stability of the corrected occlusion. (5) Resolution of the related symptoms. For the patient with open-bite on anterior and posterior teeth, this case report shows the treatment methods in combination the fixed prosthesis with the selective cutting of the natural teeth. Occlusal adjustment is no longer an elective procedure but a mandatory one for patients requiring restorations and those in treatment for TMD dysfunctions or those whose dentitions show signs of occlusal trauma. Occlusal adjustment is essential for all who do not display the above lists.

• 구강회복응용과학지
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• 제16권3호
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• pp.171-185
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• 2000

The treatment objectives of the complete oral rehabilitation are : (1) comfortably functioning temporomandibular joints and stomatognathic musculature, (2) adherence to the basic principle of occlusion advocated by Schuyler, (3) anterior guidance that is in harmony with the envelope of function, (4) restorations that will not violate the patient's neutral zone. There may be many roads to achieving these objectives, but they all convey varing degrees of stress and strain on the dentist and patient. There are no "easy" cases of oral rehabilitation. Time must be taken to think, time must be taken to plan, and time must be taken to perform, since time is the critical element in both success and failure. Moreover, a systematized and integrated approach will lead to a prognosis that is favorable and predictable. This approach facilitates development of optimum oral function, comfort, and esthetics, resulting in a satisfied patient. Such a systematized approach consists of four logical phase : (1) patient evaluation, (2) comprehensive analysis and treatment planning, (3) integrated and systematic reconstruction, and (4) postoperative maintenance. Firstly, we must evaluate the mandibular position. The results of a repetitive, unstrained, nondeflective, nonmanipulated mandibular closure into complete maxillomandibular intercuspation is not so much a "centric" occlusion as it is a stable occlusion. Accordingly, we ought to concern ourselves less with mandibular centricity and more with mandibular stability, which actually is the relationship we are trying to establish. The key to this stability is intercuspal precision. Once neuromuscular passivity has been achieved during an appropriate period of occlusal adjustment and provisionalization, subsequent intercuspal precision becomes the controlling factors in maintaining a stable mandibular position. Secondly, we must evaluate the planned vertical dimension of occlusion in relationship to what may now be an altered(generally diminished), and avoid the hazard of using such an abnormal position to indicate ultimate occlusal contacting points. There are no hard and fast rules to follow, no formulas, and no precise ratios between the vertical dimension of occlusion. Like centric relation, it is an area, not a point.

• 구강회복응용과학지
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• 제27권2호
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• pp.233-245
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• 2011

임플란트 시술에서 CAD/CAM을 포함한 컴퓨터 기술의 발달은 단순히 임플란트를 보다 정확하고, 예측 가능하게 식립하는 것뿐 아니라, 무피판(flapless) 수술과 즉시하중을 가능하게 하였다. 그러므로 술후 출혈과 불편감의 감소 및 시술시간과 치유기간을 단축시키는 장점이 있으며, 시술 후 즉시 보철물을 장착해 줌으로써 환자의 구강기능을 단기간에 회복시키고 경조직과 연조직의 형태를 보존하여 최종보철 시 유리한 환경을 만들어 줄 수 있게 되었다. 본 증례는 상 하악 무치악 상태로 내원한 40세 남성 환자로 하악 총의치의 불안정성 및 불편감 등을 호소하였으며, 하악에 임플란트 지지 고정성 보철물을 통한 수복을 원하였다. 충분한 골량, 환자의 참여도, 경제적인 여건, 전신적인 건강 등을 고려하여 하악에는 CAD/CAM 기반의 수술용 스텐트를 이용한 수술 및 미리 제작된 고정성 임시보철물을 이용하여 즉시하중을 부여하는NobelGuide 보철을 계획하였으며, 상악에는 총의치를 계획하였다. 환자의 안모를 평가하여 임시의치를 제작하였으며, 복제한 임시의치를 바탕으로 스텐트를 제작하고, 컴퓨터단층촬영을 시행하였다. 3차원으로 변환된 영상을 기반으로 하악에 7개의 고정체를 생역학적 조건과 치조골의 상태에 맞게 분산 배치하였다. 제작된 수술용 스텐트에 맞게 주모형을 제작하고, 임시고정성 보철물을 제작하여 장착함으로써 즉시하중을 부여하였다. 식립 3개월 후 골유착 정도를 평가하고 최종보철물을 제작하였다. 추후 발생할 수 있는 상악 골흡수를 방지하기 위해 주기적인 내원 및 검사를 통해 성공적인 치료가 될 수 있도록 노력하였다.

• 구강회복응용과학지
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• 제37권2호
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• pp.73-80
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• 2021

목적: 본 연구의 목적은 CAD-CAM 방식 중 절삭가공과 적층가공으로 제작한 임시 보철 재료의 색 안정성을 비교 연구하는 것이다. 연구 재료 및 방법: 절삭가공을 통해 제작한 PMMA계열, DLP타입 프린터와 광경화성 수지를 이용해 적층가공으로 제작한 bis-acryl계열 그리고 전통적인 방법으로 제작한 PMMA계열의 시편을 각 20개씩 제작하였다. 시편을 커피용액과 와인용액에 침전시킨 후, 비색계를 이용하여 4주간 매주 색 측정을 시행하였다. 색 변화(ΔE^*)값의 비교분석을 위해 One-way ANOVA와 사후 검정으로 Tukey test를 실시하였다(α = 0.05). 결과: 절삭가공을 통해 제작된 PMMA계열의 시편은 적층가공을 통해 제작된 bis-acryl계열의 시편에 비해 뛰어난 색 안정성을 보였고(P < 0.05), 전통적인 방법을 통해 제작된 PMMA계열의 시편과 유사한 색 안정성을 보였다(P > 0.05). 결론: 전치부와 같이 심미가 중요한 부위에서는 절삭가공을 통한 임시 보철물의 제작을 추천하며, 적층가공을 이용한 임시 보철물 제작 시에는 색 안정성에 대한 고려가 필요하다.