• The Journal of Korean Academy of Prosthodontics
• /
• v.39 no.3
• /
• pp.273-281
• /
• 2001

Digital subtraction radiography may be one of the most precise and noninvasive methods for assessing subtle density changes in peri-implant bone, providing additional diagnostic information on implant tissue integration in overall maintenance. The aims of this study were to evaluate density changes after first, second surgery of dental implant and to measure the amount of marginal bone loss 9 months after second surgery using digital subtraction radiography. Bone change around 30 screw-shaped implants in 16 patients were assessed on radiographs. 17 Branemark implants of 3.75mm in diameter(Nobel Biocare, Goteborg, Sweden), 2 Branemark implants of 5.0mm in diameter, 11 $Replace^{TM}$ implants of 4.3mm in diameter(Nobel Biocare, Goteborg, Sweden) were used. To standardize the projection geometry of serial radiographs of implants, customized bite block was fabricated using XCP film holder(Rinn Corporation, Elgin, IL.) with polyether impression material of Impregum(ESPE, Germany) and direct digital image was obtained. Qualitative and quantitative changes on radiographs were measured with Emago software(The Oral Diagnostic System, Amsterdam, Netherlands). The results were as follows: 1. The peri-implant bone density of 69.2% implants did not change and the peri-implant bone density of 30.8% implants decreased after 3 months following first surgery. 2. The crestal bone density of 53.9% implants decreased first 3 months after second surgery. The crestal bone density of 58.8% implants increased 9 months after second surgery. No density change was observed around the midportion of the implants after second surgery, 3. The amount of marginal bone loss between different kinds of implants showed no statistically significant differences (p>0.05). 4. More than 90% of total marginal bone loss recorded in a 9-month period occurred during the first 3 months.

• Journal of Periodontal and Implant Science
• /
• v.36 no.1
• /
• pp.253-263
• /
• 2006

Purpose: Recently, dental implant systems have been widely used for the treatment of the extraction site, but we have been confronted with many limitations in esthetics, phonetics and function. Transitional implants(TI) were developed as a method of providing fixed provisional restorations during conventional implant healing. Until now, little data have been provided on korean transitional implants. The purpose of this study is to evaluate the implant placement site histologically after 4 weeks and 8 weeks. Materials and Methods : Test group( IntermetzzoTM MEGAGEN, KOREA) and control group(Mini Drive Lock, Intra Rock, U.S.A.) were immediately placed in interseptal or interproximal bone of beagle dog after mandibular premolars extraction, and had a healing period with non-submerged state but without loading, Both TI surfaces were composed of rough surfaces. Results: In the test group, the average percentage of BIC were respectively 39.40%(SD7.35) after 4 weeks and 44.05%(16.76) after 8 weeks, and In the control group were 50.75%(1.48) and 59.40%(0.00). Discussion: We evaluated the initial ability of the osseointegration of TI through this study. Because TI is placed with a conventional implant simultaneously and loaded immediately, the ability of osseointegration is a very important factor for the success of TI during the initial healing phase. Conclusion: The results of the histological evaluation of these two groups were similar to those mentioned in other studies for osseointegration of implant.

• Journal of Periodontal and Implant Science
• /
• v.41 no.5
• /
• pp.211-217
• /
• 2011

Purpose: The marginal bone levels around implants following restoration are used as a reference for evaluating implant success and survival. Two design concepts that can reduce crestal bone resorption are the microthread and platform-switching concepts. The aims of this study were to analyze the placement of microthreaded and platform-switched implants and their short-term survival rate, as well as the level of bone around the implants. Methods: The subjects of this study were 27 patients (79 implants) undergoing treatment with microthreaded and platform-switched implants between October 2008 and July 2009 in the Dental Hospital of Yonsei University Department of Periodon-tology. The patients received follow-up care more than 6 months after the final setting of the prosthesis, at which time periapical radiographs were taken. The marginal bone level was measured from the reference point to the lowest observed point of contact between the marginal bone and the fixture. Comparisons were made between radiographs taken at the time of fixture installation and those taken at the follow-up visit. Results: During the study period (average of 11.8 months after fixture installation and 7.4 months after the prosthesis delivery), the short-term survival rate of microthreaded and platform-switched implants was 100% and the marginal bone loss around implants was $0.16{\pm}0.08$ mm, the latter of which is lower than the previously reported values. Conclusions: This short-term clinical study has demonstrated the successful survival rates of a microthread and platform-switched implant system, and that this system is associated with reduced marginal bone loss.

• The Journal of Advanced Prosthodontics
• /
• v.2 no.3
• /
• pp.97-101
• /
• 2010

A 23-year-old female with aggressive periodontitis was treated using dental implants and LAVA system. The severely compromised teeth were extracted irrespective of initial conservative periodontal treatment. An implant-supported overdenture with 4 implants was fabricated for the maxilla and all-ceramic restorations for the mandible. Esthetic and functional goals were achieved with team approach involving periodontists and prosthodontists. This case report describes a treatment procedure for a generalized aggressive periodontitis patient with severe bone resorption.

• The Journal of Korean Academy of Prosthodontics
• /
• v.52 no.4
• /
• pp.352-358
• /
• 2014

They have been recently introduced many aesthetic implant prosthesis using with zirconia and CAD/CAM. However, there are many limitations in their gingival and occlusal region. In this case, submucosal zirconia implant prosthesis were fabricated with CAD/CAM system. The connection of these screw cement retained prosthesis and titanium abutment was designed to 1mm above the fixture. The clinical results were satisfactory on the aesthetics and function.

• The Journal of Advanced Prosthodontics
• /
• v.7 no.5
• /
• pp.380-385
• /
• 2015

PURPOSE. The aim of this study was to determine the frequency of significant panoramic radiographic findings and eventual treatment requirements before conventional or implant supported prosthetic treatment in asymptomatic edentulous patients. MATERIALS AND METHODS. A total of 743 asymptomatic edentulous patients were retrospectively evaluated using a digital panoramic system. We analyzed the radiographic findings, including impacted teeth, retained root fragments, foreign bodies, severe atrophy of the posterior maxillary alveolar bone, mucous retention cysts, soft tissue calcifications and radiopaque-radiolucent conditions. RESULTS. Four-hundred-eighty-seven (65.6%) patients had no radiographic finding. A total of 331 radiographic findings were detected in 256 (34%) patients. In 52.9% (n=175) of these conditions, surgical treatment was required before application of implant-supported fixed prosthesis. However, before application of conventional removable prosthesis surgical treatment was required for 6% (n=20) of these conditions. CONCLUSION. The edentulous patients who will have implant placement for implant-supported fixed prosthesis can frequently require additional surgical procedures to eliminate pathological conditions.

• The Journal of Advanced Prosthodontics
• /
• v.1 no.2
• /
• pp.102-106
• /
• 2009

STATEMENT OF PROBLEM. Screw loosening has been a common complication and still reported frequently. PURPOSE. The purpose of this study was to evaluate abrasion of the implant fixture and TiN coated abutment screw after repeated delivery and removal with universal measuring microscope. MATERIAL AND METHODS. Implant systems used for this study were Osstem and 3i. Seven pairs of implant fixtures, abutments and abutment screws for each system were selected and all the fixtures were perpendicularly mounted in liquid unsaturated poly-esther with dental surveyor. After 20 times of repeated closing and opening test, the evaluation for the change of inner surface of implant and TiN-coated abutment screw, and weight loss were measured. Mann-Whitney test with SPSS statistical software for Window was applied to analyze the measurement of weight loss. RESULTS. TiN-coated abutment screws of Osstem and 3i showed lesser loss of weight than non-coated those of Osstem and 3i (P < .05, Mann-Whitney test). CONCLUSION. Conclusively, TiN coating of abutment screw showed better resistance to abrasion than titanium abutment screw. It was concluded that TiN coating of abutment screw would reduce the loss of preload with good abrasion resistance and low coefficient of friction, and help to maintain screw joint stability.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.28 no.4
• /
• pp.397-406
• /
• 2012

Loss of tooth results in remodeling and resorption of surrounding alveolar bone which causes atrophic edentulous ridge and gradually decreasing gingival attachment. As a result, edentulous patients face difficulty in using dentures due to pain, decrease of support, decline of masticatory efficiency of complete denture. To improve this, overdenture with implant in the mandible and attachment are considered as a treatment of choice as a favorable treatment. In this case, a patient with edentulous ridge for long period is rehabilitated by complete denture in maxilla and implant overdenture using Locator$^{(R)}$ attachment in mandible.

• The Journal of Korean Academy of Prosthodontics
• /
• v.50 no.1
• /
• pp.36-43
• /
• 2012

Purpose: To analyze the stress distribution of the implant and its supporting structures through 3D finite elements analysis for implants with different hexagon heights and to make the assessment of the mechanical stability and the effect of the elements. Materials and methods: Infinite elements modeling with CAD data was designed. The modeling was done as follows; an external connection type ${\phi}4.0mm{\times}11.5mm$ Osstem$^{(R)}$ USII (Osstem Co., Pusan, Korea) implant system was used, the implant was planted in the mandibular first molar region with appropriate prosthetic restoration, the hexagon (implant fixture's external connection) height of 0.0, 0.7, 1.2, and 1.5 mm were applied. ABAQUS 6.4 (ABAQUS, Inc., Providence, USA) was used to calculate the stress value. The force distribution via color distribution on each experimental group's implant fixture and titanium screw was studied based on the equivalent stress (von Mises stress). The maximum stress level of each element (crown, implant screw, implant fixture, cortical bone and cancellous bone) was compared. Results: The hexagonal height of the implant with external connection had an influence on the stress distribution of the fixture, screw and upper prosthesis and the surrounding supporting bone. As the hexagon height increased, the stress was well distributed and there was a decrease in the maximum stress value. If the height of the hexagon reached over 1.2mm, there was no significant influence on the stress distribution. Conclusion: For implants with external connections, a hexagon is vital for stress distribution. As the height of the hexagon increased, the more effective stress distribution was observed.

• Journal of Periodontal and Implant Science
• /
• v.43 no.1
• /
• pp.12-17
• /
• 2013

The purpose of this review is to examine the performance of attachments used in implant-supported overdenture (IOD) in both clinical and in vitro settings and report the compiled findings, comparisons, and trends in the research literature. Articles published in PubMed on IOD attachment systems and performance were reviewed. Non-original articles were excluded. For each article included, the type of study, number of implants, number of attachment systems, and study outcome were recorded. Of the 283 articles found, 158 met the inclusion criteria. Ninety-four articles were clinical studies and 64 articles were in vitro studies. Studies on retention were the most common for in vitro studies, and four or more attachment systems were compared in most articles with significant differences in outcome. A clinical outcome of one attachment system was most common for clinical studies, while most studies had neutral outcomes overall. Ball attachment was the most commonly tested IOD attachment system. The trend in the literature showed that there is a large discrepancy between the study designs and outcomes between the clinical and the in vitro studies for IOD. Further clinical studies that can validate in vitro research should be encouraged to address this discrepancy between the two areas.