• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.1
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• pp.33-44
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• 2015

Purpose: This study is to evaluate the clinical significance of the platform switching concept by comparing the marginal bone loss around platform-matched and platform-switched implants. Materials and Methods: Date of implant placement, diameter, length, implant-abutment connection type and absence of splinting prosthesis were investigated on patients who performed treatment with implant placement at Wonkwang University Dental Hospital Implant Center. To measure the marginal bone loss around implants, periapical radiographs of patient were used when implant was placed and when visited the center most recently by using the program, Emago advanced v5.6. Results: As a result of observing on 150 implants of 82 patients for 6 - 63 months, platform-matched implants showed $1.16{\pm}0.54mm$, platform-switched implants showed $0.68{\pm}0.27mm$ of marginal bone loss. Conclusion: It was considered that there is the positive effect to reduce marginal bone loss around platform-switched implants.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.4
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• pp.266-272
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• 2010

Purpose: The purpose of this study was to investigate the effects of the surface morphology of the implant neck on marginal bone stress measured by using finite element analysis in six implant models. Materials and methods: The submerged type rescue implant system (Dentis co., Daegu, Korea) was selected as an experimental model. The implants were divided into six groups whose implant necks were differently designed in terms of height (h, 0.4 and 1.0 mm) and width (platform width, w = 3.34 + 2b [b, 0.2, 0.3 and 0.4 mm]). Finite element models of implant/bone complex were created using an axisymmetric scheme. A load of 100 N was applied to the central node on the top of crown in parallel with the implant axis. The maximum compression stress was calculated and compared. Results: Stress concentration commonly observed around dental implants did not occur in the marginal bone around all six test implant models. Marginal bone stress varied according to the implant neck bevel which had different width and height. The stress was affected more markedly by the difference in height than in width. Conclusion: This result indicates that the implant neck bevel may play an important role in improving stress distribution in the marginal bone area.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.169-174
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• 2008

Statement of problem: Changes of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. It was proposed that bone-retention elements such as microthreads at the coronal part of implant might help maintain the marginal bone level. Purpose: This study was designed to evaluate the effect of microthread configuration within the marginal coronal portion of the implant fixture at the marginal bone changes after loading around two different external hex implants. Material and methods: Twenty-four patients were included and randomly assigned to treatment with $Br{{\aa}}nemark$ system implants (Group 1, rough-surfaced implants, n=20) and Oneplant system implants (Group 2, rough-surfaced neck with microthreads, n=20). Clinical and radiographic examinations were conducted at baseline (implant loading) and 1 year postloading. Data analysis was performed by the SAS statistical package version 9.1.3 (SAS Institute, Cary, NC, USA) and the final model was calculated by the MIXED procedure (three-level ANCOVA) for marginal bone change of each test group at baseline and 1 year follow-up. Results: Comparing to baseline, significant differences were noted in marginal bone level changes for the 2 groups at 1 year follow-up (P<0.05). Group 1 had a mean crestal bone level changes of $0.83{\pm}0.31mm$; Group 2 had a mean crestal bone level changes of $0.44{\pm}0.36mm$. Rough-surfaced with microthreads implants showed significantly less marginal bone loss than rough surfaced neck without microthread implants. Conclusion: A rough surface with microthreads at the implant was beneficial design to maintain the marginal bone level against functional loading.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.127-138
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• 2012

This study is to assess the effect of preload level on the stress development at the marginal cortical bone surrounding implant neck. A finite element model was created for a single implant placed in the lower jaw bone. An external load of 100N was applied on the top of abutment at 30 degree with the implant axis in lingo-buccal direction. Five different preloads, i.e. 0, 200, 400, 600, 800N were applied to the abutment stem to investigate if and/or how the preload affects on the marginal bone stress. Differences in the marginal bone stress were recorded depending on the level of preload. On the other hand, the tensile stress on the marginal cortical bone decreased in models of higher preload. Preloads between abutment/fixture can increase compressive stresses in the marginal cortical bone although the amount may be insignificant as compared to those generated by functional forces.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.1
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• pp.1-13
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• 2012

Short implants are used in parts which have anatomical structures like maxillary sinus, inferior alveolar nerve and limited alveolar height due to severe alveolar bone resorption. In these case, there are no need of additional bone augmentation so there are advantages like reduced entire treatment time, reduced patient's discomfort and protection of important anatomical structures. The aim of this study is, in implants whose length is less than 10mm, to analyze the impact of implant length, diameter, location of implant placement, presence of bone graft, presence of prosthesis splinting on survival rates and marginal bone resorption. The samples used in this study were 227 implants, less than 10mm, placed in 137 patients in Wonkwang university dental hospital implant center. From dental charts the information about implant length, diameter, location of implant placement, presence of bone graft, presence of prosthesis splinting were obtained. Emago advanced v5.6(Oral diagnostic systems, Amsterdam, The Netherlands)program was used to measure the amount of marginal bone resorption. Out of total 227 implants, resulting in 96.5 % of survival rate. There was a tendency toward higher failure rates for the maxilla and bone graft site. No significant difference in marginal bone resorption was found associated with length of implants(p>0.05) and neither with the diameter of implants. Among the risk factors examined, more failure rates of short implants can be attributed to poor bone quality in the maxilla and presence of bone graft. At implants under 10mm, length, diameter, location of implant placement, bone graft and splinting of prosthesis didn't affect marginal bone loss.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.3
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• pp.176-183
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• 2012

Purpose: This study examined the clinical success rate of Mg titanate implants (M Implant system, Shinhung, Korea), which employ a Mg coating method, by evaluating the marginal bone loss and implant stability using radiographs and Osstell$^{(R)}$, over a 1 year. Materials and methods: The locations of the implants placement were divided into 4 areas; the maxillary and mandibular premolars and molars. In the maxilla, 8 and 9 implants were inserted in the premolar and molar areas, respectively. In the mandible, 11 and 51 implants were inserted in the premolar and molar areas. Marginal bone loss and ISQ of all implants (79) were measured after insertion, mounting the prosthetic appliance, and 1, 3, 6, and 12 months after loading. The marginal bone loss was measured from the radiograph using XCP bite, which was customized, and the implant stability measured using Osstell$^{(R)}$. Fisher's exact test (${\alpha}$=.05) was used to compare the success rates of each region. Results: The mean marginal bone loss for the upper and lower jaws were 1.537 mm and 1.172 mm. The mobility showed a non-significant reduction or increase according with time. The success rates were accounted for 94.12% and 98.39% in the upper and lower jaws; the premolars and molars were accounted for 100% and 96.67%. The two cases of early failure resulted from failure of primary stability during implant insertion. The late failures were not observed for 1 year after adding a loading to the implants. Conclusion: The Mg titanate implant showed good primary stability and good clinical results in both healing and function.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.280-289
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• 2018

Purpose: The purpose of this randomized clinical trial is to determine whether implant length and the crown-to-implant (C/I) ratio influence implant stability and peri-implant marginal bone loss (MBL). Materials and Methods: 46 patients with single tooth missing in the posterior molar region of the mandible were included in this study. 19 implants (CMI IS-III $active^{(R)}$ long implant) of 5.0 mm diameter and 10 mm length were installed for the control group, while 27 implants (CMI IS-III $active^{(R)}$ short implant) of 5.5 mm diameter and 6.6, 7.3 or 8.5 mm length were placed for the experimental group. Each implant was inserted and immediately loaded using the digitally pre-fabricated surgical template and provisional restoration. The CAD-CAM monolithic zirconia crown was fabricated at 3 months after the surgery as a definitive restoration. The ISQ value and the MBL was measured at 48 weeks after the surgery. The correlation between the C/I ratio, MBL, and secondary implant stability was analyzed. Results: Successful results in terms of ISQ and MBL were achieved with both groups. There was no significant difference between the groups in terms of ISQ values and MBL at 48 weeks after the surgery (P > 0.05). No significant correlation was found between the C/I ratio and secondary stability as well as the C/I ratio and the MBL (P > 0.05). Conclusion: The influence of C/I ratio in both groups was not shown on the stability nor the marginal bone loss in implants supporting single crown of the mandible. Short implant could be a preferable alternative option in the reduced bone height mandible under the limited condition despite its higher C/I ratio.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.4
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• pp.417-429
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• 2009

Since the introduction of the concept of osseointegration in dental implants, high long-term success rates have been achieved and accepted as viable option for the treatment of fully and partially edentulous patients. Although the use of domestic implants have increased dramatically, there are few studies on domestic implants with clinical and objective long-term data. 96 endosseous implants placed in 31 patients at Wonkwang University Sanbon Dental Hospital were examined to determine the effect of various factors on implant survival rate and marginal bone loss, through clinical and radiographic results. The design of endosseous implant used to this study is straight with the microthread.(GS II RBM Fixture) 1. 3 fixtures were lost, resulting in 96.9% cumulative survival rate. 2. Survival rate in fifties was significantly lower (93.6%) and no significant difference in marginal bone loss was found according to gender. 3. Survival rates were 95.6% in the maxillary molar area and 97.3% in the mandible molar area. 4. No significant difference in survival rate was found according to presence of bone grafts, type of prostheses, implant position, and length and diameter of implant. 5. A factor influencing marginal bone loss was presence of type of prostheses, while facters such a length, diameter of fixture and bone grafts had no statistically significant effect on crestal bone loss. This study indicates the amount of marginal bone loss around implant has maintained a relative stable during follow-up periods.

• 대한치과보철학회:학술대회논문집
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• 1998.05a
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• pp.55-55
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• 1998

• 대한치과보철학회:학술대회논문집
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• 1994.12a
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• pp.47-47
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• 1994