Comparison of the Strain on the Alveolar Ridge According to the Occlusal Scheme of Complete Dentures

최원준,임영준,김창회,김명주 대한턱관절교합학회 2010 구강회복응용과학지 Vol.26 No.1

The purpose of this study was to compare the strain on the alveolar ridge in the centric, eccentric and protrusive position according to the occlusal scheme (bilateral balanced occlusion with 33 degree anatomical teeth, group B; monoplane occlusion with non-anatomical teeth, group M; lingualized occlusion with 33 degree anatomical teeth and non-anatomical teeth, group L; of complete dentures. Experimental dentures were set bilateral balanced occlusion, lingualized occlusion and monoplane occlusion. They are analysed through T-Scan II(Tekscan, Boston, U.S.A) and 1.5mm thick layer was removed from the denture-supporting surface of resin model and then replaced with silicone to simulate resilient edentulous ridge mucosa. A 4x6 linear strain gauge is attached to the 1st premolar and 1st molar area. The strain values are recorded according to the occlusal scheme in the centric, eccentric and protrusive position after uniformly applying 50 N and 150 N force through a Universal Testing Machine(instron® 5567, Bluehill 2.0 software ,U.S.A.) with the models mounted in the articulator. When performing centric and protrusive occlusion, the three groups of occlusal scheme were compared in the anterior region and in the posterior region. The strains of each group were also compared in the working side and in the non-working side during eccentric excursion. It was observed that the strain in the bilateral balanced occlusion showed a higher value than the lingualized occlusion and monoplane occlusion in every position except the non-working side. However, during the eccentric movement the strain value in the non-working side showed the lowest value in the bilaterally balanced occlusion. The strain change amount from the working side or centric occlusion to non-working side and also the strain variation rate within the non-working side showed the highest value in bilateral balanced occlusion.

Nylon Thread를 이용한 mouse 에서의 Transient middle cerebral artery occlusion (MCAO) model 확립

임병철,성지희,김하나,박승우 한국콘텐츠학회 2019 한국콘텐츠학회논문지 Vol.19 No.7

Introduction: In aged people, stroke incidence is increased. But standardized experimental animal protocol study for the research of stroke therapy is rare. There is little report on the success rate of cerebral artery occlusion model using standardized Nylon thread length of precise thread end-size controlled. Method: In this study, the operator intended the occlusion of middle cerebral artery (MCA) using 0.18±0.02mm end 5-0 Nylon thread. Middle cerebral artery occlusion was induced for 60min under isoflurane anesthesia. After 60min, the operator removed the Nylon thread and reperfusion was induced for 23hrs. The mice was killed 23hrs after reperfusion and infarction area of brain was confirmed by 1.5% TTC (2,3,5-tryphenyl tetrazolium chloride) staining. Results: According to end size and insert length of Nylon thread, Middle cerebral artery occlusion (n= 50), internal carotid artery occlusion (n= 14), distal middle cerebral artery occlusion (n= 36), anterior cerebral artery (n= 1) were induced. And no infarction (n= 50) was observed. Conclusion: According to weight of mice, the operator induced reversible cerebral artery occlusion model by different insert length (30.0~36.9g : 9.0mm, 37.0~40.0g : 9.5mm) of Nylon thread. Success of cerebral artery occlusion model was confirmed by checking infarction area using TTC staining. The success rate (66.9%, 101/151) of reversible cerebral artery occlusion model in the mouse and the operational conditions are shown. 서론: 최근 노년층에서 뇌졸중 발병률이 증가하고 있다. 현재 뇌졸중 치료제 및 방법이 많이 개발되어 있으나 치료 후에도 후유증 등이 많이 남게 된다. 그래서 아직도 많은 과학자나 임상 의사들이 이를 치료하기 위한 약물 및 방법을 연구하고 있는 실정이다. 많은 연구 중 뇌졸중 치료 연구를 위한 표준화된 실험 동물연구는 드물며, 표준화된 Nylon thread를 이용한 중대뇌동맥 폐쇄모델(MCAO, middle cerebral artery occlusion)의 성공률에 대한 연구는 거의 없다방법: 본연구는 0.18±0.02mm 의 지름을 가진 5-0 Nylon thread를 중대뇌동맥에 삽입하였다. 60분 동안 삽입한 후에 봉합해 놓았던 부위를 다시 절개하여 Nylon thread를 빼내고, 막았던 혈관의 매듭을 풀어주어, 다시 혈액이 공급되게 하였다. 그로부터 23시간 후에 뇌를 내어 1mm 두께로 자른 후 1.5% TTC (2',3',5'-triphenyl-tetrazolium chloride)로 15분간 염색하고, 4% PFA(paraformaldehyde)로 15분 동안 고정하였다. 결과: Nylon thread를 삽입하여, MCA occlusion 50마리, ICA occlusion 14마리, 제대로 된 MCAO model보다 좀 더 깊게 들어간 distal MCAO model 36마리, 너무 깊은 MCA나 ACA까지 들어가서 상보적인 괴사를 나타내는 occlusion model 1마리, 그리고 경색이 일어나지 않은 마우스 50마리를 확인하였다. 결론: 이에 본 연구에서는 Nylon Thread를 생쥐의 무게에 따라 32~36g 인 생쥐는 9mm로 삽입하여주고, 37~40g인 생쥐는 9mm+0.5mm의 깊이로 삽입하여서 1hr의 occlusion과 23hr의 reperfusion을 주어 생쥐를 TTC 염색을 통하여 괴사가 일어난 부분을 확인하였고, 생쥐에서 가역적인 뇌혈관 경색으로 151말중 101마리에서 뇌경색을 유도 할 수 있었다(66.9%).

망막분지정맥폐쇄환자에서 정맥폐쇄 위치에 따른 임상적 양상

박가희,최경식,Ka Hee Park,MD,Kyung Seek Choi,MD 대한안과학회 2013 대한안과학회지 Vol.54 No.8

Purpose: To evaluate clinical patterns according to the occlusion site in patients with branch retinal vein occlusion. Methods: Ninety-one branch retinal vein occlusion patients were divided into 4 groups according to the occlusion site based on the description by Duke-Elder and Wybar: Papillary retinal vein occlusion group (group A), main retinal vein occlusion group (group B), minor retinal vein occlusion group (group C), and retinal venule occlusion group (group D). The following factors were analyzed retrospectively: baseline/final visual acuity, visual improvement, macular thickness, and macular circulatory states. Results: The macular thickness (μm) was 575.33 ± 178.44 in group A, 511.92 ± 218.02 in group B, 397.21 ± 144.51 in group C, and 336.68 ± 120.55 in group D. The retinal ischemic area (DD) was 22.00 ± 13.28 in group A, 18.26 ± 10.12 in group B, 12.52 ± 10.52 in group C, and 12.36 ± 11.92 in group D, which was found to be significantly greater in the group with the higher branch occlusion site (p < 0.05). However, visual acuity, macular circulatory states and other clinical characteristics were not significantly different. Conclusions: Occlusion site is a relating factor for retinal ischemic area and macular thickness in patients with Branch retinal vein occlussion, but which is not a prognostic factor for final visual acuity.

Role of the Peripheral Vestibular End Organ in the Expression of c-Fos Protein in the Medial Vestibular Nucleus Following Occlusion of the Anterior Inferior Cerebellar Artery

김나리,이재희,최명애,박병건,김민선,박병림 대한평형의학회 2012 Research in Vestibular Science Vol.11 No.2

Background and Objectives: The present study investigated the role of the peripheral vestibular end organ in vestibular symptoms and temporal changes in expression of c-Fos protein in the vestibular nuclei following anterior inferior cerebellar artery (AICA) occlusion using rats with unilateral or bilateral labyrinthectomy. Materials and Methods: Expression of c-Fos protein in the vestibular nuclei was measured 2,12, 24, and 48 hours after AICA occlusion. Results: Unilateral AICA occlusion significantly induced expression of c-Fos protein bilaterally in the medial, inferior,superior, and lateral vestibular nuclei. Following AICA occlusion, the medial vestibular nucleus (MVN) showed the highest expression of c-Fos protein among the 4 vestibular nuclei. The expression of c-Fos protein was asymmetric between the bilateral MVN, showing higher expression in the MVN contralateral to the side of AICA occlusion compared to the ipsilateral MVN. The degree of asymmetry in c-Fos protein expression between the bilateral MVN peaked 12 hours after AICA occlusion. The expression of c-Fos protein gradually decreased 24 hours after AICA occlusion and returned to control levels 48 hours after AICA occlusion. Unilateral labyrinthectomy significantly decreased expression of c-Fos protein in the MVN ipsilateral to the side of labyrinthectomy following AICA occlusion. Moreover,bilateral labyrinthectomy significantly decreased expression of c-Fos protein in the bilateral MVN flowing AICA occlusion. Conclusion: These results suggest that afferent signals from the peripheral vestibular end organ are crucial to the expression of c-Fos protein in the MVN following AICA occlusion and that expression of c-Fos protein is sustained for 24 hours after AICA occlusion.

Comparative evaluation of peri-implant stress distribution in implant protected occlusion and cuspally loaded occlusion on a 3 unit implant supported fixed partial denture: A 3D finite element analysis study

Paramba Hitendrabhai Acharya,Vilas Valjibhai Patel,Sareen Subhash Duseja,Vishal Rajendrabhai Chauhan 대한치과보철학회 2021 The Journal of Advanced Prosthodontics Vol.13 No.2

Purpose. To assess peri-implant stress distribution using finite element analysis in implant supported fixed partial denture with occlusal schemes of cuspally loaded occlusion and implant protected occlusion. Materials and methods. A 3-D finite element model of mandible with D2 bone with partially edentulism with unilateral distal extension was made. Two Ti alloy identical implants with 4.2 mm diameter and 10 mm length were placed in the mandibular second premolar and the mandibular second molar region and prosthesis was given with the mandibular first molar pontic. Vertical load of 100 N and and oblique load of 70 N was applied on occlusal surface of prosthesis. Group 1 was cuspally loaded occlusion with total 8 contact points and Group 2 was implant protected occlusion with 3 contact points. Results. In Group 1 for vertical load, maximum stress was generated over implant having 14.3552 Mpa. While for oblique load, overall stress generated was 28.0732 Mpa. In Group 2 for vertical load, maximum stress was generated over crown and overall stress was 16.7682 Mpa. But for oblique load, crown stress and overall stress was maximum 22.7561 Mpa. When Group 1 is compared to Group 2, harmful oblique load caused maximum overall stress 28.0732 Mpa in Group 1. Conclusion. In Group 1, vertical load generated high implant stress, and oblique load generated high overall stresses, cortical stresses and crown stresses compared to vertical load. In Group 2, oblique load generated more overall stresses, cortical stresses, and crown stresses compared to vertical load. Implant protected occlusion generated lesser harmful oblique implant, crown, bone and overall stresses compared to cuspally loaded occlusion.

간헐외사시에서 단안차폐 후 측정한 사시각의 변화

김성훈,김숙영,권정윤.Sung-Hoon Kim. M.D.. Sook-Young Kim. M.D.. Jung-Yoon Kwon. M.D. 대한안과학회 2005 대한안과학회지 Vol.46 No.7

Purpose: To measure the amount of increased angle of strabismus at far and near distance after 1 hour of monocular occlusion in intermittent exotropia and to evaluate the surgical outcome. Methods: Fifty-five patients operated on for intermittent exotropia from May 2002 to February 2003 and followed for at least 6 months postoperatively were prospectively studied. In all patients, the angle of deviation was measured at 6 m and 33 cm before and 1 hour after monocular occlusion. Patients with an increase of exodeviation less than 5PD after occlusion were defined as non-responders, and were operated for the pre-occlusion angle (Group 1). Patients with an increased angle more than 5PD after occlusion were defined as responders, and were operated according to the pre-occlusion (Group 2) or post-occlusion (Group 3) angle. Results: Thirty (54.5%) of the 55 patients were responders of distant deviation with an increase of 6.20±2.96 PD after occlusion. Forty-three (78.2%) of the 55 patients were responders of near deviation with an increase of 13.4±7.12PD after occlusion. Group 3 who underwent surgery for the increased angle after occlusion had a higher frequency of satisfactory surgical outcome (71.4%) than group 1 (68.0%) and group 2 (62.5%). However, these differences were not statistically significant (P>0.05, Chi-square test). Conclusions: The angle of strabismus in patients with intermittent exotropia who undergo surgery should be measured at 1 hour after monocular occlusion to improve the surgical outcome.

Effect of different lateral occlusion schemes on peri-implant strain: A laboratory study

Lo, Jennifer,Abduo, Jaafar,Palamara, Joseph The Korean Academy of Prosthodonitics 2017 The Journal of Advanced Prosthodontics Vol.9 No.1

PURPOSE. This study aims to investigate the effects of four different lateral occlusion schemes and different excursions on peri-implant strains of a maxillary canine implant. MATERIALS AND METHODS. Four metal crowns with different occlusion schemes were attached to an implant in the maxillary canine region of a resin model. The included schemes were canine-guided (CG) occlusion, group function (GF) occlusion, long centric (LC) occlusion, and implant-protected (IP) occlusion. Each crown was loaded in three sites that correspond to maximal intercuspation (MI), 1 mm excursion, and 2 mm excursion. A load of 140 N was applied on each site and was repeated 10 times. The peri-implant strain was recorded by a rosette strain gauge that was attached on the resin model buccal to the implant. For each loading condition, the maximum shear strain value was calculated. RESULTS. The different schemes and excursive positions had impact on the peri-implant strains. At MI and 1 mm positions, the GF had the least strains, followed by IP, CG, and LC. At 2 mm, the least strains were associated with GF, followed by CG, LC, and IP. However, regardless of the occlusion scheme, as the excursion increases, a linear increase of peri-implant strains was detected. CONCLUSION. The peri-implant strain is susceptible to occlusal factors. The eccentric location appears to be more influential on peri-implant strains than the occlusion scheme. Therefore, adopting an occlusion scheme that can reduce the occurrence of occlusal contacts laterally may be beneficial in reducing peri-implant strains.

A Comparison of Visual Occlusion Methods

Jungchul Park 대한인간공학회 2011 大韓人間工學會誌 Vol.30 No.5

Objective: This study compares two visual occlusion methods for the evaluation of in-vehicle interfaces. Background: Visual occlusion is a visual demand measuring technique which uses periodic vision/occlusion cycle to simulate a driving(or mobile) environment. It has been widely used for the evaluation of in-vehicle interfaces. There are two major implementation methods for this technique: (1) occlusion using PLATO(portable liquid crystal apparatus for tachistoscopic occlusion) goggles; (2) occlusion using a software application on a touchscreen device. Method: An experiment was conducted to examine the visual demand of an in-vehicle interface prototype using the goggle-based and the touchscreen-based occlusion methods. Address input and radio tuning tasks were evaluated in the experiment. Results: The results showed that, for the radio tuning task, there were no significant differences in total shutter open time and resumability ratio between the two occlusion conditions. However, it took longer for the participants to input addresses with the touchscreen-based occlusion. Conclusion & Application: The results suggest that touchscreen-based method could be used as an alternative to traditional, goggle-based visual occlusion especially in less demanding visual tasks such as radio tuning.

Effect of different lateral occlusion schemes on peri-implant strain: A laboratory study

Jennifer Lo,Jaafar Abduo,Joseph Palamara 대한치과보철학회 2017 The Journal of Advanced Prosthodontics Vol.9 No.1

PURPOSE. This study aims to investigate the effects of four different lateral occlusion schemes and different excursions on peri-implant strains of a maxillary canine implant. MATERIALS AND METHODS. Four metal crowns with different occlusion schemes were attached to an implant in the maxillary canine region of a resin model. The included schemes were canine-guided (CG) occlusion, group function (GF) occlusion, long centric (LC) occlusion, and implant-protected (IP) occlusion. Each crown was loaded in three sites that correspond to maximal intercuspation (MI), 1 mm excursion, and 2 mm excursion. A load of 140 N was applied on each site and was repeated 10 times. The peri-implant strain was recorded by a rosette strain gauge that was attached on the resin model buccal to the implant. For each loading condition, the maximum shear strain value was calculated. RESULTS. The different schemes and excursive positions had impact on the peri-implant strains. At MIand 1 mm positions, the GF had the least strains, followed by IP, CG, and LC. At 2 mm, the least strains were associated with GF, followed by CG, LC, and IP. However, regardless of the occlusion scheme, as the excursion increases, a linear increase of peri-implant strains was detected. CONCLUSION. The peri-implant strain is susceptible to occlusal factors. The eccentric location appears to be more influential on peri-implant strains than the occlusion scheme. Therefore, adopting an occlusion scheme that can reduce the occurrence of occlusal contacts laterally may be beneficial in reducing peri-implant strains.

The Time Evolution of Cerebral Apoptosis in the Permanent Middle Cerebral Artery Occlusion Model in Rats

Shin, Cheol-Sik,Choi, Byung-Yon,Jung, Eul-Soo,Kim, Sang-Woo,Chang, Chul-Hoon,Cho, Soo-Ho The Korean Neurosurgical Society 2005 Journal of Korean neurosurgical society Vol.37 No.1

Objective: The purpose of this study is to determine the time evolution and distribution of cerebral apoptosis using the middle cerebral artery occlusion model in rats. Methods: A total of twenty four male rats - with 2, 3, 4, 6, 8, 12, 24 and 48 hours of middle cerebral artery occlusion respectively - were studied. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling(TUNEL) method was used for the observation of the apoptotic cells. The apoptotic ratio was calculated and the distribution of apoptosis was inspected in the pyriform cortex, basal ganglia and middle cerebral artery territory cortex. The rats were divided into three groups(Group I : $2{\sim}4$ hours of occlusion, Group II : $6{\sim}$12 hours of occlusion, Group III : $24{\sim}48$ hours of occlusion). Results: In this study, the proportion of apoptosis increased with the duration of middle cerebral artery occlusion and reached a maximum after about 12 hours of middle cerebral artery occlusion. The mean values of the apoptotic ratio were $30.7{\pm}11.3%$ in group I, $60.8{\pm}2.6%$ in group II and $48.7{\pm}0.7%$ in group III. The distribution of apoptosis differed in the pyriform cortex, basal ganglia and middle cerebral artery territory cortex according to the duration of time of the middle cerebral artery occlusion. Conclusion: In the middle cerebral artery occlusion model of the rats, apoptosis is found to increase according to the occlusion time, reaching a peak after 6 hours, and the distribution of apoptosis changed from the pyriform cortex to the basal ganglia and middle cerebral artery territory cortex.