• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
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• v.61 no.12
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• pp.705-709
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• 2018

It is challenging to achieve sufficient hearing gain in patients with mixed hearing loss. In chronic middle ear diseases, conventional passive reconstructive surgeries often result in suboptimal hearing gain and additional hearing aids may have limitations due to insufficient sound amplification, occlusion effect, acoustic feedback, and skin irritation. Middle ear implantation (MEI) using Vibrant Soundbridge (VSB) is another option for auditory rehabilitation in mixed hearing loss as well as sensorineural hearing loss. The floating mass transducer of VSB can be placed on various middle ear structures either directly or using different types of couplers in order to deliver vibratory mechanical energy to the cochlea. We report a patient who presented with bilateral mixed hearing loss due to chronic otitis media and had limitations using conventional hearing aids in the worse hearing ear. The patient was successfully treated with MEI using the Bell coupler together with middle ear surgery in a single step.

• Hip & pelvis
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• v.34 no.1
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• pp.35-44
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• 2022

Purpose: Osteosynthesis has been recommended for treatment of Pauwels type III femoral neck fractures in young patients. However, no implant of choice has been reported so far. This study was conducted in order to compare the fixation stability of two conventional fixation methods with three different novel fixed angle devices in this type of fracture. Materials and Methods: A total of 25 composite femurs (4th Generation Saw bone; Pacific Research Laboratories, USA) corresponding to human bone were used. Pauwels type III fracture type was uniformly reproduced. Specimens were fixed with a cannulated screw, cannulated screw with cable, and Intertan nail, dynamic hip screw, and IKEY nail. Measurement of failure loads and the rotational change of the femoral head fragment was performed for evaluation of fixation stability. Results: All implants were compared with cannulated screw and dynmaic hip screw. No meaningful improvement was observed for the cannulated screw with cable compared with the cannulated screw and dynamic hip screw. Meaningful improvement in load-to-failure and y-rotation and z-rotation was observed for both the Intertan nail and IKEY nail compared with the cannulated screw. However, compared with the dynamic hip screw, only the IKEY nail showed improvement in the same profile but the Intertan nail did not. Conclusion: Among novel fixed angle devices, meaningful improvement was observed for the IKEY nail compared with conventional implants. Strengths of this implant include biomechanical stability and simplicity of surgical technique, indicating that it may be another good option for osteosynthesis of Pauwels type III femoral neck fractures.

• Journal of Periodontal and Implant Science
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• v.25 no.2
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• pp.418-437
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• 1995

The effect of the hydroxyapatite coatings on Titanium implants has been the subject of recent investigations. So far, the use of HA coating remains substantially controversial.This study was aimed to evaluate histologically the bone healing patterns around titanium plasm sprayed(TPS) amd HA-coated implant after implantation into the femur neck of ten adult dogs. After implantation, animals were sacrificed at the intervals of 2,4,6,8 and 12 weeks.The fluorescent dyes were injected on the postoperative 4th and 12th week into the animals supposed to be killed at the 12th week. The morphology and direction of new bone formation was similar in both TPS and HA-coated implants.There was a tendency toward more bone formation in the cortical bone area than in the cancellous bone area. Histologically,in the interface of the HA-coated implants, bone response and bone maturation was faster, compared to the TPS implants in the 2nd and 4th week. By fluorescent microscopy, new bone formation was active in the 4th week around both implants and was directed from the periosteum overlying cortical bone to the cancellous bone. These results suggest that the bone formation and maturation is faster during the early healing stage in the interface of the HA-coated implant and where the cortical bone quality is poor, HA coated implant is superior to the TPS implant in the early phase of new bone formation.

• Journal of Periodontal and Implant Science
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• v.44 no.1
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• pp.2-7
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• 2014

Implants have been widely used in restorative treatment for patients who have undergone head and neck cancer surgery. With the development of combination treatment of head and neck cancer, radiotherapy has been a common means of therapy. However, it could induce various changes in hard and soft tissues and reduce the success and survival rate of the implants. Some research, using either animal models or clinical studies, have shown that certain strategies could be used for improving the survival rate of implants. In this review, we discussed the changes in both hard and soft tissues, which may reduce the survival rate of the implants, and the proposed methods for improving the survival rate of patients after radiotherapy.

• Korean Journal of Head & Neck Oncology
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• v.7 no.1
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• pp.3-9
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• 1991

Brachytherapy is a method of radiotherapy in advantage to achieve better local control with minimum radiation toxicity in comparison with external irradiation because radiation dose is distributed according to the inverse square low of gamma-ray emitted from the implanted sources. The main characteristics of brachytherapy are delivering of higher dose to target volume shortening of total treatment period and sparing of normal tissue. Recent development of iridium ribbons for low dose rate implant provides improvement of technology of brachytherapy in terms of safety and efficiency. High dose rate method. on the other hand, is effective to avoid unnecessary expoure of medical personnel.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.19 no.2
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• pp.143-148
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• 1997

Cancer therapy for the head and neck malignoncy by surgery, radiotherapy, or combined modalities may cause substantial aesthetic and functional problems for the patient. The placement of osseointegrated implants into irradiated bone should only be performed when the predictability of achieving and maintaining osseointegration is high and the risk of developing of osteoradionecrosis is low. There are many benefits that irradiated patients may gain from the use of implants. A successful implant-retained prosthesis is dependent upon the implants attaining osseointegraton and then sustaining it during functional loads. The use of implants in irradiated patients requires high implant success rates that are acceptable to warrant their use. We report a case and review the literatures about implants in irradiated bone. In that case, the patient were undergone tumor resection and inner-table mandiblectomy due to squamous cell carcinoma of lower posterior gingiva. But 5 year later, the tumor were recurred, we resected the tumor and applied the radiation therapy. After then, we installed four IMZ implants after hyperbaric oxygenation, and made prosthesis using those implants. Until now they don't have any complications.

• The Journal of Korean Academy of Prosthodontics
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• v.54 no.3
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• pp.280-285
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• 2016

Mandible defects could be caused by congenital malformations, trauma, osteomyelitis, tumor resection. If large areas are included for reconstruction, those are primarily due to tumor resection defects. The large jaw defect results in a problem about mastication, swallowing, occlusion and phonetics, and poor esthetics causes a lot of inconvenience in daily life. It is almost impossible to be a part underwent mandibular resection completely reproduced, should be rebuilt artificially. This case is of a patient who was diagnosed with squamous cell carcinoma pT1N0M0, stage I in February 2004 and received surgery (combined mandibulectomy and neck dissection operation (COMMANDO) in oromaxillofacial surgery) in March 2004, by implant assisted removable partial denture. We could obtain good retention and stability through sufficient coverage and implant holding. Follow up period was about four years. Mandibular left third molar regions have been observed to have resorption of surrounding bone, and periodic check-ups are necessary conditions.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.2
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• pp.169-182
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• 2005

The purpose of this study was to compare the stress distribution around the surrounding bone according to the splinted and non-splinted conditions on the finite element models of the two implant crowns with the different vertical bone level. The finite element model was designed with the parallel placement of the two fixtures ($4.0mm{\times}11.5mm$) with reverse buttress thread on the mandibular 1st and 2nd molars. As the bone quality, the inner cancellous bone and the outer 2 mm cortical bone were designed, and the cortical and cancellous bone were assumed to be perfectly bonded to the implant fixture. The splinted model(Model 1) had 2 mm contact surface and the non-splinted model(Model 2) had $8{\mu}m$ gap between two implant crowns. Two group (Splinted and non-splinted) was loaded with 200 N magnitude in the vertical and oblique directions on the loading point position on the central position of the crown, the 2 mm and 4 mm buccal offset point from the central position. Von Mises stress value was recorded and compared in the fixture-bone interface in the bucco-lingual and mesio-distal sections. The results were as follows; 1. In the vertical loading condition of central position, the stress was distributed on the cortical bone and the cancellous bone around the thread of the fixture in the splinted and non-splinted models. In the oblique loading condition, the stress was concentrated toward the cortical bone of the fixture neck, and the neck portion of 2nd molar in the non-splinted model was concentrated higher than that of 1st molar compared to the splinted model. 2. In the 2 mm buccal offset position of the vertical loading compared to the central vertical loading, stress pattern was shifted from apical third portion of the fixture to upper third portion of that. In the oblique loading condition, the stress was distributed over the fixture-bone interface. 3. In the 4 mm buccal offset position of the vertical loading, stress pattern was concentrated on the cortical bone around the buccal side of the fixture thread and shifted from apical third portion of the fixture to upper third portion of that in the splinted and non-splinted models. In the oblique loading, stresses pattern was distributed to the outer position of the neck portion of the fixture thread on the mesio-distal section in the splinted and non-splinted models. Above the results, it was concluded that the direction of loading condition was a key factor to effect the pattern and magnitude of stress over the surrounding bone of the fixture under the vertical and oblique loading conditions, although the type with or without proximal contact did not effect to the stress distribution.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.83-94
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• 2004

The purpose of this study was to compare the distributing pattern of stress according to the types of occlusal load on the finite element models of the splinted implant prostheses. The finite element model was designed with the parallel placement of two fixtures ($4.0mm{\times}11.5mm$) on mandibular first and second molars. The cemented crowns for mandibular first and second molars were made. Three-dimensional finite element model was created with the components of the implant, surrounding bone and cemented crowns. Two types of occlusal load, the point load and the surface load within 0.5 mm radius circle, were applied to the finite element models with 200N magnitude in axial(along the long axis of the implant and oblique(angulation of $30^{\circ}$ to the long axis) directions perpendicular to cuspal incline. Loads were positioned from the center of central fossa and to distance of 2 mm and 4 mm apart from the center of central fossa. Von-Mises stresses were recorded and compared in the fixtures and sections. The results were as following : 1. Under axial loading at the central fossa, the stress was distributed along the fixture except for the apical portion, not relative to both point & surface contacts. 2. With offset distance increasing, the highest stresses were concentrated in the neck portion of the fixture. 3. The maximum von Mises stress under the oblique load was greater than that under the axial load. 4. Under the oblique load, the highest stress were concentrated in the buccal side and lingual neck portion of the fixture with offset distance increasing. The results had a tendency to increase the stress on the neck portion of fixture with the offset and oblique loads increasing. The design of occlusal scheme should be allowed to distribute stress axially in maximum intercuspation and to decrease the angulation of cuspal incline.

• Clinical and Experimental Otorhinolaryngology
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• v.15 no.1
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• pp.77-83
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• 2022

Objectives Common cavity deformity is a rare congenital bony labyrinth malformation associated with profound hearing loss. Cochlear implants are widely used for hearing rehabilitation for common cavity deformities; however, the reported prognosis is poor. Due to the deformed anatomical structure, it is important to consider the position of the electrodes to maximize the performance of the cochlear implant. The present study discusses the impact of electrode placement on hearing outcomes. Methods A retrospective medical chart review of eight common cavity deformity patients (10 cochlear implants) who received cochlear implants was performed at a single university hospital. In all eight patients, implant surgery was performed using single-slit labyrinthotomy. Electrodes wer e manually bent before insertion to prevent misplacement and to reduce physical damage to the neuroepithelium. Results Four of the 10 electrodes were misplaced, with their tips placed in the anterior semicircular canal or internal auditory canal. However, after implant surgery, all patients-including those with misplaced electrodes-gained auditory perception and improved hearing function. One patient who had electrodes that did not contact the inner wall of the cavity showed limited activity of the electrodes (27%) compared to others (64%-100%). Conclusion Proper contact of the electrode with the inner wall was more likely to be important for cochlear implant success in cases of common cavity deformity than appropriate placement of the electrode tip.