• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.4
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• pp.265-277
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• 2014

Purpose: The purpose of this study was to investigate the differences of displacement pattern depending on type of sliding jig and application method during maxillary molar distalization with temporary anchorage devices (TADs). Materials and Methods: Maxilla with normal tooth size and arch shape was selected to create a 3-dimensional finite element model, which included the bracket, orthodontic main archwire, removable sliding jig (R-jig). The orthodontic mini-implant anchorage was set 8 mm superiorly from main archwire, buccally between the second premolar and first molar. The base experimental design was Condition 1, which was composed $0.019{\times}0.025$ inch stainless steel (SS) of wire size of R-jig, 200 gm force, un-tied state. And the other designs varied to wire size of R-jig, magnitude of force. The results are as follows. Results: As the wire size of R-jig was increased, the deformation of R-jig was decreased. However, the displacement of second molar wasn't different each other. As the force to second molar was increased, the more displacement of second molar was observed, and the more distal tipping movement, vetical displacement was observed. Conclusion: R-jig can get distal teeth movement in orthodontic treatment without side effects.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.3
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• pp.228-238
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• 2020

In order to deliver fixed partial denture to a patient successfully, dentist must take into many considerations beforehand. Patient's occlusal pattern should be fully understood before delivering any type of prosthesis, whether it's canine guidance or group function occlusion. In order to do so, movement of mandible should be recorded precisely. Introduced by Meyers in 1933, functionally generated path technique (FGP) has been successfully used to record mandibular movement with various materials, such as wax, and utilize it in fabricating precise prosthesis. In the following cases, patients showed secondary caries or endodontic-periodontic lesion on maxillary molars. Root canal treatment and subgingival curettage were done for each patient. Since the long term prognosis of each tooth was questionable, lateral force should be minimized. In order to do so, FGP technique was used to record mandibular movements precisely. Instead of using conventional plaster impression, intra-oral scanning of wax tracing was done to fabricate prosthesis efficiently. After delivery of fixed partial denture, favorable outcome was obtained.

• Journal of Dental Rehabilitation and Applied Science
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• v.19 no.3
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• pp.169-183
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• 2003

According to our recent investigation that the increase in the occlusal vertical dimension made the appendage muscle strength got higher, the occlusal appliances were made by increasing the occlusal vertical dimension "from the centric relation" position of the mandible. In this experiment, the authors tried to study the change in the appendage muscle strength due to increase in occlusal vertical dimension from intercuspal position(ICP) of mandible with the same subjects and manner as the former experiment. For this study, ten male athletes in a mean age of 23 year who were joined the former study were selected. All the subjects had a complete or almost complete set of natural teeth and reported no subjective symptoms of temporomandibular disorders. Upper and lower casts were mounted on the semi-adjustable articulator at the intercuspal position and a point was marked on the attached gingival area between the right canine and the right 1st. premolar in each upper and lower cast. From the points, the occlusal vertical dimension was increased by 2mm, 3.5mm and 5mm, and then each 10 maxillary type occlusal splint at each 3-increased position were fabricated with heat curing clear acrylic resin. Including the intercuspal position, the 3 kinds of occlusal splints were placed on the subjects individually, and then isokinetic muscle strength on 7 parts of the human appendage which are shoulder, knee, ankle, wrist, forearm, elbow and hip was measured with the CYBEX 6000 SYSTEM (Lumex, NewYork, USA). The results were as follows: The highest mean value in muscular strength was shown at the position of 2mm-increased vertical dimension. The muscle strength during internal/external rotation of shoulder and knee, plantarflexion of ankle, flexion of elbow, and flexion and extension of hip at the increased occlusal vertical dimension position were significantly higher than them at the intercuspal position (p<0.05). Only in view of the increase in the appendage muscle strength, regardless of the way of making the occlusal splints by elevating the occlusal vertical dimension from the centric relation position or intercuspal position, the occlusal splints had an effect on the increase of isokinetic muscle strength at the occlusal vertical dimension which increased within the proper range on the habitual arc of closure.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.317-324
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• 2008

The objective of this study was to test effects of (1) where the occlusal contact points locate on a full veneer crown, and (2) which direction the contact forces are directed to, on the stresses within the luting cement layer that might suffer microfracture. A total of 27 finite element models were created for a mandibular first molar, combining 9 different locations of the occlusal contact points and 3 different loading directions. Type 3 gold alloy was used for crown material with a chamfer margin, and the luting cement material was glass ionomer cements in uniform thickness of $75{\mu}m$. Modeled crowns were loaded at 100 N. Different patterns in the cement stress were observed in the vicinity of the buccal and lingual margins. Whereas, the peak stress in buccal margin occurred approximately 0.5 mm away from the external surface, the highest stress in lingual margin was observed at approximately 1 mm. Significantly different distribution of stresses was recorded as a function either of the location of the occlusal contact points or of the loading direction. Higher stresses were produced by more obliquely acting load, and when the loaded point was in the vicinity of the cusp tip.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.247-251
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• 2011

Botulinum toxin type A (BoNT-A) is used for treating bilateral masseter hypertrophy since 1994. Recently there have been more clinical studies in this area, with some authors reporting that BoNT-A can reduce the size of the masseter muscle, as documented by photography, ultrasonography, computed tomography, and 3D(three dimensional) laser scan. However, earlier studies were only for bilateral masseter hypertrophy cases, not for unilateral masseter hypertrophy cases. The aim of this study was to use 3D laser scanning to evaluate changes in the external facial contour induced by unilateral BoNT-A injection. BoNT-A was injected into hypertrophic masseter muscle unilaterally in 10 patients with asymmetric masseter hypertrophy. The clinical effects of unilaterally injected BoNT-A were evaluated before the injection and 4, 8, and 12weeks after the injection using 3D laser scan. And the mean values of both sides (injection and non-injection sides) were compared with. At injection side, mean values of the volume and the bulkiest height at each time point diminished significantly between pre-injection and 4, 8, and 12weeks post-injection. At non-injection side, in contrast, mean values of the volume and the bulkiest height diminished also but less than that of injected side, and there was no statistical significance. In this limited study, we concluded that the unilaterally BoNT-A injection side showed greater mean values of the reduction of muscle volume than non-injection side at 4, 8, and 12 weeks after the injection.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.263-273
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• 2016

In the implant prosthetic procedure, the soft tissue reaction was varied with the material and surface treatment of the abutment. It may be the cause of the peri-implantitis, and hence it can affect the long-term prognosis of the implant prosthesis. Titania and zirconia abutment presented superior biocompatibility and stable soft tissue reaction, while gold alloy abutment showed unfavorable reaction sometimes. A soft tissue reaction can be differed by the surface characteristics even in the same material type. Because rougher surface induces a bacterial attachment, the part contacting a soft tissue should have smooth surface. Additional surface treatment can enhance the cellular response without increasing bacterial attachment. Repeated removal and insertion of the abutment and the shape of the abutment may affect the soft tissue reaction, also. Ultrasonic cleaning and argon plasma cleaning are effective way to clean the retained micro-dust on the customized abutment.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.1
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• pp.32-38
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• 2018

Purpose: The purpose of present study was to retrospectively analyze the survival rate of narrow diameter implant less than 3.6 mm by initial stability and radiographic measurements. Materials and Methods: In total, 24 patients who received 38 narrow diameter implants (${\leq}3.6mm$ in diameter, ${\geq}7mm$ in length) were enrolled in this retrospective study. The cumulative survival rate was calculated and various factors were investigated according to the implant platform diameter, body diameter, length, position, concomitant use of guided bone regeneration in implant placement and final prosthesis type. Initial stability was investigated with implant stability quotient (ISQ) value. The mesial and distal marginal bone level (MBL) change was calculated with radiography. Results: The overall survival rate was 92.11%. Mean ISQ value and MBL change of survival implants was 66.26 and $0.14{\pm}0.31mm$, respectively. None of the implants with platform diameters larger than the body diameter failed. Conclusion: In conclusion, the findings of present study suggest that narrow diameter implant could be predictable treatment in narrow alveolar ridge.

• Journal of Periodontal and Implant Science
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• v.31 no.2
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• pp.277-285
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• 2001

Periodontal disease is characterized by inflammation and subsequent loss and/or damage to tooth-supporting tissues such as bone, cementum,and periodontal ligament. Periodontal ligament and cementum are the key tissues in the initial process of regeneration following periodontal disease. Therefore, studies on cementoblasts, which form cementum are emphasized. It is still unclear which cells cementoblast differentiate from. This study was conducted under the hypothesis that PDL fibroblast can differentiate into either cementoblast or osteoblast depending on the conditions of surrounding tissue. Clinically, with excessive traction force of orthodontic appliances or excessive occlusion hypercementosis is observed, and this has been confirmed histologically. Consequently, activation of cementoblast can be expected in rats when mechanical stimuli are given to PDL fibroblast. Therefore, the purpose of this article is to prove that PDL fibroblast differentiates into cementoblast in rats under mechanical stimuli using histologic and molecular methods. In this study, twenty rats were given hard diet. Ten of them were sacrificed after 1 week, and the others were sacrificed after two weeks. Slides were made from tooth specimen, and they were studied under the microscope. In addition, PDL fibroblast and cementum from the extracted teeth were analyzed with Northern blotting. In histologic examination, as time passed, PDL fibroblast migrated to the dentin side, differentiated into cementoblast, and formed new cementum. In Northern blotting, it was found that mRNA expression of cementoblast-specific proteins such as BSP, OC, OPN, and type I collagen were more prominent in rats sacrificed after 2 weeks of hard-diet than rats sacrificed after 1 week. From these findings we can conclude that PDL fibroblast can differentiate into cementoblast under mechanical stimuli. We think that 'Rat Models' used in this study will be beneficial to future studies regarding cementoblast.

• Journal of Dental Rehabilitation and Applied Science
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• v.35 no.4
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• pp.206-213
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• 2019

Purpose: Most of studies dealing with abfractions are limited to the buccal surfaces of the teeth. In this study, we analyzed the cause for abfraction by investigating the incidence of palatal side abfractions in maxillary posterior teeth. Materials and Methods: We investigated a total of 3193 maxillary posterior teeth by an intraoral examination, model observation, and observation of virtual model fabricated using model scanning. We recorded the results and classified them depending on the type of teeth, age, gender, and side of arches. We also performed Chi-square test to evaluate the statistical significance among the groups (α = 0.05). Results: The incidence of palatal side abfraction of the maxillary molars (10.8%) was higher than the premolars (6.8%), and among them, the incidence of the 1st molars (39.1%) were the highest. The incidence of palatal side abfraction increased with age and was statistically significant (P < 0.05). There was no statistical significance in the difference by gender (P > 0.05); in the case of arches, left arch showed higher incidence and it was statistically significant (P < 0.05). Conclusion: Palatal side abfraction in maxillary posterior teeth was frequently observed in the maxillary 1st molars, and the incidence increased with age. This result suggests that the main reason for abfraction is due to occlusal force.

• Journal of Chest Surgery
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• v.40 no.2 s.271
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• pp.136-139
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• 2007

Bilateral popliteal artery entrapment syndrome is a rare vascular disease, which leads to ischemic claudication as a result of disturbance to the blood flow from the abnormal relationship of the popliteal artery to the gastrocnemius muscle, a fibrous band or the popliteus muscle in the young male population. A 58-years-old male patient, complaining of ischemic claudication, coldness and 3rd toe gangrene of left leg of 1 month's duration was admitted to our institution. His left ankle-brachial index was decreased; therefore, a femoral artery angiography was peformed, which revealed a total occlusion below the distal superficial femoral artery of the left leg. An EKG revealed atrial fibrillation, suggestive of a thromboembolism of the popliteal artery due to atrial fibrillation; therefore, Urokinase thrombolysis was attempted. After the Urokinase thrombolysis, popliteal artery entrapment syndrome was diagnosed, with MRI then performed for an anatomical diagnosis. The popliteal artery entrapment was type 1, where the popliteal artery was displaced medial to the Gastrocnemius head. After complete removal of the popliteal artery aneurysm, interposition was performed with a contra lateral greater saphenous vein graft. A mild right popliteal artery aneurysm still remained, but surgery was not performed. Currently, the patent is surviving, without complications. Herein, the good results obtained for the surgical treatment of a severely affected leg, and the conservative treatment of a mildly affected leg, are reported.