• Journal of Dental Rehabilitation and Applied Science
• /
• v.18 no.4
• /
• pp.321-329
• /
• 2002

Bending moments results from offset overloading of dental implant, which may cause stress concentrations to exceed the physiological capacity of cortical bone and lead to various kinds of mechanical failures. The purpose of this study was to compare the distributing pattern of stress on the finite element models with the different angulated placement of dental implant in mandibular posterior missing areas. The three kinds of finite element model, were designed according to 3 main configurations: Model 1(parallel typed placement of 2 fixtures), Model 2(15. distal angulated placement of one fixture on second molar area), Model 3(15. mesial angulated placement of one fixture on second molar area). The cemented crowns for mandibular first and second molars were made on the two fixtures (4mm 11.5). Three-dimensional finite element models by two fixtures were constructed with the components of the implant and surrounding bone. A 200N vertical static load were applied to the center of central fossa and the point 2mm apart from the center of central fossa on each model. The preprocessing, solving and postprocessing procedures were done by using FEM analysis software NISA/DISPLAY IV Version 10.0((Engineering Mechanics Research Corporation, USA). Von Mises stresses were evaluated and compared in the supporting bone, fixtures, and abutment. The results were as following : (1) Under the point loading at the central fossa, the direction of angulated fixture affected the stress pattern of implants. (2) Under the offset loading, the position of loading affected more on the stress concentration of implants compare to the angulated direction of implants. The results had a tendency to increase the stress on the supporting bone, fixture and screw under the offset loads when the placement angulation of implant fixture is placed toward mesial or distal direction. In designing of the occlusal scheme for angulated placement, placing the occlusal contacts axially during chewing appears to have advantages in a biomechanical viewpoint.

• The Journal of the Korean bone and joint tumor society
• /
• v.12 no.2
• /
• pp.171-175
• /
• 2006

The involvement in the spine of eosinophilic granuloma is not common. Especially, involvement of cervical spine and posterior neural arch is quite rare. In addition, radiographic findings including magnetic resonance images of eosinophilic granuloma are manifested as vertebral body collapse, loss of pedicle and paravertebral soft mass formation; it must be differentiated with other conditions, such as malignant bone tumor, metastatic cancer or tuberculous spondylitis. We experienced three cases of eosinophilic granuloma involving posterior neural arch of C4, C7, and body of C4 respectively, which were performed surgical treatment and achieved complete healing. We report these cases with review of literatures.

• Journal of the Korean Orthopaedic Association
• /
• v.54 no.2
• /
• pp.187-191
• /
• 2019

Spinal epidural hematoma (SEH) can occur naturally or traumatically and is most common in patients with an underlying disease of the vascular structure or coagulation disorder. Most SEHs occur naturally for no apparent reason, and epidural hematoma caused by trauma is less common, comprising 1.0%-1.7% of total spinal injuries. Few reports of SEH induced cauda equine syndrome resulting from low-energy injury caused by osteoporotic vertebral compression fractures are available. The authors experienced a case of delayed SEH after hemorrhage due to a low-energy injury in an elderly patient. No cases in Korea have been reported; therefore, this case is reported with a review of the relevant literature.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.39 no.3
• /
• pp.158-167
• /
• 2023

As digital technology has advanced in the field of dentistry, the use of computer-aided design/computer-aided manufacturing (CAD/CAM) has brought changes to the stages of dental treatment. The use of CAD/CAM technology in dental restoration offers clinical efficiency and convenience by reducing production time and appointment intervals, while also simplifying the fabrication process to reduce errors. In this case, digital replication and printing of temporary teeth were used to aid a patient with complex medical histories and physical disabilities. The final impression obtained with silicone impression material included information on the vertical dimension, centric relation, and the angle and length of the anterior teeth, which shortened the production time and appointment intervals and increased patient satisfaction. The final restoration was fabricated using milling and monolithic disc techniques, demonstrating appropriate stability, retention, and support, resulting in functional and aesthetic satisfaction.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.9
• /
• pp.307-313
• /
• 2012

This paper proposes a hand-eye laser range finder (LRF) based welding plane recognition method for autonomous robotic welding. The robot welding is the process of joining a metal piece and the welding plane along the welding path predefined by the shape of the metal piece. Thus, for successful robotic welding, the position and direction of the welding plane should be exactly detected. If the detected position and direction of the plane is not accurate, the autonomous robotic welding should fail. For precise recognition of the welding plane, a line on the plane is detected by the LRF. For obtaining the line on the plane, the Hough transform is applied to the obtained data from the LRF. Since the Hough transform is based on the voting method, the sensor noise can be reduced. Two lines on the plane are obtained before and after rotation of the robot joint, and then the direction of the plane is calculated by the cross product of two direction vectors of two lines. For verifying the feasibility of the proposed method, the simulation with the robot simulator, RoboticsLab developed by Simlab Co. Ltd., is carried out.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.20 no.2
• /
• pp.109-120
• /
• 2004

INTRODUCTION: The build-up method has been used for application of porcelain powder on the metal framework to make final tooth shape conventionally. This method takes time and need skill to mimic final shade and shape of porcelain fused to metal crown. The purpose of this study was to develop standard shape and shade laminating porcelain forms to reduce build-up time. METHODS: To make tooth form porcelain paste, several liquid organic compounds were added to conventional feldspathic porcelain. The amount of additives and rheologic property were tested to find out best composition. Comparison of mixing methods to reduced porosity, proper heating schedule, and measurement of shrinkage amount and residual organic materials were performed to set-up standard procedures. Finally, biaxial flexural strength and color of preformed laminated paste porcelain were compared with those of porcelain which fabricated by the conventional build-up method. RESULTS: There was no significant difference in physical properties and color stability between two fabrication methods after various testing methods. Conclusion: This new build-up method can be applied to fabricate the PFM crown and bridge without any loss of strength and optical properties.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.33 no.4
• /
• pp.291-298
• /
• 2017

It is challenging to produce esthetic implant restoration in the narrow anterior maxilla region where insufficient volume of alveolar bone could limit the angle and position of implant fixture, if preceding bone augmentation is not considered. Ideal angle and position of implant fixture placement should be established to reproduce harmonious emergence profile with marginal gingiva of implant prosthesis, bone augmentation considered to be preceded before implant placement occasionally. In this case, preceding bone augmentation has been operated before esthetic implant prosthesis in narrow anterior maxilla region. Preceded excessive bone augmentation in buccal area allowed proper angulation of implantation, which compensates unfavorable implant position. Provisional restorations were corrected during sufficient period to make harmonious level of marginal gingiva and interdental papilla. The definite restoration was fabricated using zirconia core based glass ceramic. Functionally and esthetically satisfactory results were obtained.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.36 no.1
• /
• pp.41-47
• /
• 2020

Purpose: The purpose of this study was to evaluate the flexural strength and reliability of highly translucent colored zirconia for all ceramic restoration. Materials and Methods: Bar-shaped specimens (25 × 4 × 2.5 mm) were prepared from highly translucent monolithic zirconia. Three experimental groups were set up according to color (shade A0, A1, and A3). For each group, 20 specimens were prepared. Flexural strength was determined using a 3-point flexural test and results were analyzed with one-way ANOVA test. Weibull statistical analysis provided 2 parameter estimates: Weibull modulus and characteristic strength. X-ray diffraction (XRD) analysis was performed. Results: There was statistically significant difference between uncolored (Shade A0) and colored (shade A1 and A3) (P < 0.05), but there was no difference between colored groups (P > 0.05). The uncolored group had higher reliability compared with colored study groups. On x-ray diffraction analysis of each group, typical peaks of tetragonal phase appeared in all groups. Conclusion: Within the limitations of this in vitro study, coloring highly translucent zirconia had significant effect on flexural strength and reliability. Therefore, clinicians should be careful when using highly translucent colored zirconia to prevent breakage of veneering ceramic and enhance aesthetics.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.43 no.4
• /
• pp.612-617
• /
• 2014

Anti-inflammatory effects of turmeric (Curcuma longa L.) rich in polysaccharides, as well as free of curcuminoids and turmerones were investigated in acute and chronic inflammatory models. Activity against the acute phase of inflammation was evaluated in carrageenan-induced paw edema and xylene-induced ear edema models. The results showed that turmeric extract significantly decreased paw edema volume in the first and third hours after carrageenan injection ($P{\leq}0.05$). Turmeric extract at all dose levels also significantly inhibited xylene-induced ear edema formation ($P{\leq}0.05$). Activity against chronic inflammation was also evaluated in cotton pellet-induced granuloma model. Turmeric extract significantly ($P{\leq}0.05$) decreased the weight of granuloma tissue on cotton pellets in a dose-dependent manner when compared to the vehicle control. Thus, the findings of the study suggest that turmeric extract in effective against both acute and chronic inflammation.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.25 no.4
• /
• pp.349-360
• /
• 2009

Purpose: As the esthetic demands of dental implant patients are increased, the demands of zirconia as implant abutment material are also increased. It has non-metalic color, good biocompatibility, high strength and high toughness. Even thought the advatage of zirconia abutment, there are a few studies about mechanical properties of zirconia abutment. This study evaluated the mecanical strength with compressive bending strength and endurance limit of implant-zirconia abutment assembly. Materials and Methods: Static and cyclic loading of implant-Zirconia abutment assembly were simulated under worst case condition according to ISO. Test groups were implants of external butt joint with straight regular diameter and angled regular diameter zirconia abutment, implant of external butt joint with narrow straight diameter zirconia abutment and implant of internal conical joint with straight narrow diameter zirconia abutment. All test group were evaluated the mecanical strength with compressive bending strength and endurance limit. After fatique testing, fracture surface were examined by SEM. Results: The compressive bending strengths exceed 927N. Regular diameter zirconia abutment were stronger than narrow diameter zirconia abutment(P<.05). The endurance limits ranged from 503N to 868N. Conclusion: Within the limitation of this study, zirconia implant abutment exceeded the estabilished values for maximum incisal biting forces reported in the literature.