• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.141-147
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• 2008

This study was aimed to develop an instrument for real-time measurement of fluid conductance and to investigate the hydrodynamics of dentinal fluid. The instrument consisted of three parts; (1) a glass capillary and a photo sensor for detection of fluid movement, (2) a servo-motor, a lead screw and a ball nut for tracking of fluid movement, (3) a rotary encoder and software for data processing. To observe the blocking effect of dentinal fluid movement, oxalate gel and self-etch adhesive agent were used. BisBlock (Bisco) and Clearfil SE Bond (Kuraray) were applied to the occlusal dentin surface of extracted human teeth. Using this new device, the fluid movement was measured and compared between before and after each agent was applied. The instrument was able to measure dentinal fluid movement with a high resolution (0.196 nL) and the flow occurred with a rate of 0.84 to 15.2 nL/s before treatment. After BisBlock or Clearfil SE Bond was used, the fluid movement was decreased by 39.8 to 89.6%.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.297-306
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• 2000

Lateral cephalometric X-ray films in maximal intercuspation and maximal opening of 68 children were taken and analyzed to examine the pattern of condylar movement and to study the relationship between opening movement and morphologic factors of craniofacial skeleton. The results were as follows : 1. The mean value of maximal opening capacity was 47.1mm, condylar moving distance was 18.1mm, horizontal condyle movement was 17.5mm, vertical condyle movement was 3.8mm and condylar moving angle was $13.1^{\circ}$. 2. The maximal opening capacity had positive relationship with the length of anterior cranial base, mandible and maxillary complex and with posterior facial height and had negative relationship with articular angle, sagittal jaw relationship. 3. Vertical condyle movement and condylar moving angle had positive relationship with articular angle and had negative relationship with gonial angle. 4. Horizontal condyle movement and condylar moving distance had positive relationship with the length of maxillary complex.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.3
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• pp.323-337
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• 2010

The objective of this study was to examine the availability of the new impression coping by comparing with conventional coping in implant pick-up impression technique. Five implant fixtures were installed on #14, 21, 23, 25, 27 in acrylic resin model. That model with 5 fixtures was standard model, which was divided 3 groups; using new flag type impression coping, conventional impression coping splinted with self-curing resin, conventional impression coping without splinting. We made metal circular cones for calculation 3-dimensional coordinates by attaching to implant fixtures or analogs. Three-dimensional relationships of each model were calculated. Data was analyzed by multiple ANOVA and Bonferroni. The accuracy of impression between using new flag type impression coping and conventional impression coping did not show differences in 3 - dimensional analysis.Within limitations of this study, the new flag type impression coping is available in implant pick-up impression technique.

• Journal of the korean academy of Pediatric Dentistry
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• v.36 no.4
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• pp.556-562
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• 2009

Ectopic eruption of the maxillary first permanent molar means that the molar erupts out of the normal position and is arrested in its eruption by the second primary molar. This local eruption disturbance results in a premature atypical resorption on the distal part of the second primary molar. In most irreversible cases, the second primary molar is lost prematurely, either by spontaneous exfoliation or by extraction, In cases of doubt as to whether the eruption is of the irreversible type or not, careful radiographic observation period for a few months would be valuable in evaluating the possibilities of the tooth's freeing itself. The purpose of this study was to determine the characteristics and occurrence of the ectopic eruption of the maxillary first permanent molar. A descriptive, observational, retrospective study was done using the radiographs of 25 conseutive patients, who were in the first phase of mixed dentition. A method was designed to evaluate the amount of pathologic resorption of the second maxillary primary molar and the mesial angulation of the first permanent molar. The study showed that the most important etiologic factor was the eruption path or mesial angulation of the first permanent molars relative the chosen reference lines.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.373-388
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• 2010

Fracture causes serious problems in many instance of prosthetic failures. But it is hard to find the definite causes when fractures occur. Fractography encompasses the examination of fracture surfaces that contain features resulting from the interaction of the advancing crack with the microstructure of the material and the stress fields. All fractured specimens(implant retaining screw) retrieved from Gangneung-Wonju national university dental hospital for 3 years(from 2007 to 2009). After pretreatment of samples, the scanning electon microscope were used for surface examination and fracture analysis. In case of most of the fractured specimens, fracture took place by fatigue fracture and fractured surface represents fatigue striation. Fatigue striation indicate the progression of the crack front under cyclic loading, are characteristic of stage 2 crack growth. The site of crack initiation and stage 1 crack growth were not easily identified in any of the failure, presumably because of the complex microstructural features of the polycrystalline sample. In case of fractured by overload, dimpled or cleavage surface were observed. Using the interpretation of characteristic markings(ratchet mark, fatigue striation, dimple, cleavage et al) in fracture surfaces, failure events containing the crack origin, crack propagation, material deficiency could be understand. Using the interpretation of characteristic markings in fracture surfaces, cause and mechanism of fractures could be analyzed.

• The korean journal of orthodontics
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• v.26 no.5 s.58
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• pp.601-611
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• 1996

Craniofacial growth pattern is an important diagnostic data in the course of orthodontic diagnosis and treatment planning ; it also has great influence in the establishment of occlusion as well as shaping and development of face. There have been many studies to classify different craniofacial growth patterns and attempts to predict growth patterns. This study aimed to correlate craniofacial growth pattern and symphysis morphology. 120 adult patients with age from 19 to 39 (mean age : 23.1) were chosen as subjects , using lateral cephalometric films. their anterior to posterior facial height ratios were calculated. They were divided into 3 groups - clockwise growth pattern with $56\%-62\%$(36subjects), counter-clockwise growth pattern group with $65\%$-80\%$(43subjects) and normal growth pattern group with $62\%-65\%$(41subjects). Symphysis morphology and Prominence evaluation in each subject were studied and the following conclusions were drawn : 1. In comparison of symphysis morphology between the sex groups, men showed large symphysis height and prominence. 2. Concerning the symphysis morphology, the clockwise growth pattern group showed larger height, H/D ratio and actual length but smaller depth, angle, effective length and E/A ratio compared to the counter -clockwise growth pattern group. 3. Those with smaller prominance of symphysis showed clockwise growth tendency and those with larger prominance showed counter-clockwise growth tendency.

• Journal of Oral Medicine and Pain
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• v.38 no.1
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• pp.87-95
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• 2013

Osteoarthritis (OA) of the temporomandibular joint (TMJ) is a severe form of temporomandibular disorders (TMDs), presenting gradual breakdown of articular cartilage and subchondral bone by the functional load sustained to exceed the physiologic tolerance of the joint. In such a joint loaded, offensive bioactive materials such as matrix degrading proteins, cytokines, and free radicals increase in concentration to shift the tissue response in the joint to degeneration from regeneration or remodeling. Recently, it has been issued that obesity can play an offensive role in pathogenesis of OA in a metabolic way. Adipokines released by adipose cells are present at higher concentration in the arthritic joint and joints of obese individuals. However, because of conflicting data reported, further scientific study should be performed to elucidate the practical role of adipokines in pathogenesis of TMJ OA. As far as the clinical signs and symptoms of TMJ OA are not much different from those of other forms of TMD and any definitive treatment modality to control directly the bone resorptive activity is not available yet, the treatment of TMJ OA should be directed to reduce the physical load and enhance the physiologic tolerance of the joint by means of conservative treatment such as physical therapy, medication, and occlusal splint therapy for sufficient period and, if needed after that, supplementary surgical procedure such as intra-articular injection, arthrocenthesis, and arthroscopic surgery that have turned out to be effective to control OA signs and symtpoms. Enthusiastic reassurance and motivation for patients to control behaviors for themselves to reduce unnecessary functional load in daily life is very important for the joint to reach to more favorable orthopedic stability of the TMJ more quickly, guaranteeing more successful management TMJ OA.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.201-212
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• 2012

There are some similar aspects at histological and morphological characteristics between the peri-implant tissue and periodontal tissue and the direct attachment between the titanium and soft tissue around the implant called as "Functional ankylosis" can prevent the apical infiltration of inflammatory and bone resorption around implant. But, the repeated connection and disconnection of the abutment can destroy the mucosal barrier of soft tissue around the implant and can cause the marginal bone resorption. The amount of marginal bone resorption may reduced if the prosthetic abutment is placed at that time of surgery. Connection of the prosthetic abutment at surgery was limited because the low accuracy of conventional method, but by using of Cone Beam Computed Tomography(CBCT) and guide surgery, the 3-dimensional accuracy of implant placement became much higher than before and it became possible. This is a clinical case of immediate connection of prosthetic abutment and provisional restoration by using of precise CBCT diagnosis and pre-fabricated zirconia customized abutment at surgery and the alternative method is described in this article because of the clinically contentable results.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.308-316
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• 2013

The purpose of this study is to investigate the production method of posterior bridges pontic ridge lap type which prevents the infection in bridge pontic base and is able to cleanse itself, in the process of producing final prothesis that maintains healthy mucous membrane of oral cavity and interproximal papilla, minimizing diastema, is aesthetic and has no effect on pronunciation. New technology is applied to make optimal pontic base which prevent inflammation and clean itself and its products were clinically evaluated in 10 places of dental clinics in busan and gyeongnam. The making of posterior 3 unit bridge pontic base, it was presented as the new technology of forming ridge lab type and to carry out clinical validation, existing conventional method and the new technology were compared. Pontic base made with the existing conventional method cause infection and other periodontal disease by 96% but the pontic base made with the new technology cause infection and other periodontal disease by 3%. Remains of food cause infection and other periodontal disease 100% by the existing conventional method and 91% by the new technology, showing a distinct difference. However, after a gargle, the new technology had low 13%. Additionally, the pontic base made with the existing conventional method showed 71% of chance, the new technology method showed 8% of chance in terms of self-cleansing.

• Journal of Periodontal and Implant Science
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• v.30 no.4
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• pp.707-727
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• 2000

매식된 인공치아의 성공을 위해서는 적절한 교합과 수동적 적합성을 갖는 보철물의 제작과 구강내 노출 직후부터의 세균성 치태조절이 요구된다. 본 연구는 전처리(passivation과 tridodecyl - methyl - ammonium chloride(TDMAC) 처리)가 다른 타이타늄 표 면에 chlorhexidine varnish와 테트라사이클린 을 도포시 약제의 방출역학을 알아보고 구강내 치태형성의 억제정도를 평가하기 위하여 시행 되었다. 이를 위해 방출용액으로 인산완충액 성분의 인조타액을 1일${\sim}$1개월간 매일 교환하여 약제농도를 측정하고 타이타늄 박막에 잔류한 약제 활성을 측정하였으며 항균제 도포한 타이타늄 원판을 부착한 장치를 구강내 위치시킨 1일${\sim}$3주 후 원판을 제거하여 주사전자현미경으로 세균 부착상을 관찰하였다. 테트라사이클린은 TDMAC 처리된 표면에서 $10{\sim}18$일까지 유효농도로 방출되었고 표면의 유효 항균 활성은 $3{\sim}4$주간 유지되었으며, chlorhexidine varnish 도포 시에는 TDMAC 전처리시 초기에 $3{\sim}7$일 간 증가한 유효 항균 활성을 방출하여 매식지대치 등에 이러한 항균제도포 시 매식치 주위환경에 항균활성 공급원으로 작용할 수 있음을 보였다. 주사현미경적 관찰시 모든 타이타늄 표면에서 구강내 위치 30분 후에는 세균이 부착되어 있지 않고 타액 단백질 성분에서 유래한 것으로 보이는 피막물질이 표면을 부분 또는 전면에 걸쳐 덮고 있었다. 구강내 노출 2시간 후 항균제 미도포 표본들에는 약간의 구균이 단층으로, $1{\sim}3$일 후에는 부분적으로 두꺼운 세균층을 형성하였고 7일 후에는 표면전체에 걸쳐 세균층이 덮여있었으며 주로 구균과 약간의 간균이 주종을 이루었다. 항균제 도포시 구강내 노출 1주일 이전까지는 미도포군에 비해 치태형성이 지연되는 경향을 보였지만 2주 이후에는 세균 수나 치태형성 양상이 유사하였다. 이 연구로부터 항균제 도포시 1주일 이전의 초기 치태형성을 감소시킬 수 있음을 알 수 있었으며 이러한 연구결과는 타이타늄 임프란트 지대치 표면에 항균제의 도포가 임상적으로 유용할 수 있음을 시사하였다.