• 대한치과보철학회지
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• 제44권4호
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• pp.414-420
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• 2006

Purpose : The purpose of this study is to use finite element analysis to predict the fatigue life of an implant system subjected to fatigue load by mastication (chewing force). The reliability and the stability of implant system can be defined in terms of the fatigue strength. Not only an implant is expensive but also it is almost impossible to correct after it is inserted. From a bio-engineering standpoint, the fatigue strength of the dental implant system must be evaluated by simulation (FEA). Material and Methods Finite element analysis and fatigue test are performed to estimate the fatigue strength of the implant system. Mesh of implant is generated with the actual shape and size. In this paper, the fatigue strength of implant system is estimated. U-fit (T. Strong, Korea, internal type). The stress field in implant is calculated by elastic-plastic finite element analysis. The equivalent fatigue stress, considering the contact and preload stretching of a screw by torque for tightening an abutment, is obtained by means of Sine's method. To evaluate the reliability of the calculated fatigue strength, fatigue test is performed. Results: A comparison of the calculated fatigue strength with experimental data showed the validity and accuracy of the proposed method. The initiation points of the fatigue failure in the implant system exist in the region of high equivalent fatigue stress values. Conclusion: The above proposed method for fatigue life estimation tan be applied to other configurations of the differently designed and improved implant. In order to prove reliability of prototype implant, fatigue test should be executed. The proposed method is economical for the prediction of fatigue life because fatigue testing, which is time consuming and precision-dependent, is not required.

• The Journal of Advanced Prosthodontics
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• 제9권3호
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• pp.195-199
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• 2017

PURPOSE. The objective of this study was to determine the cumulative survival rate (CSR) and associated risk factors of Implantium implants by retrospective clinical study. MATERIALS AND METHODS. Patients who received Implantium implants (Dentium Co., Seoul, Korea) at Korea University Guro Hospital from 2004 to 2011 were included. The period between the first surgery and the last hospital visit until December 2015 was set as the observation period for this study. Clinical and radiographic data were collected from patient records, including all complications observed during the follow-up period. Kaplan-Meier analysis was performed to examine CSR. Multiple Cox proportional hazard model was employed to assess the associations between potential risk factors and CSR. RESULTS. A total of 370 implants were placed in 121 patients (mean age, 56.1 years; range, 19 to 75 years). Of the 370 implants, 13 failed, including 7 implants that were lost before loading. The 10-year cumulative survival rate of implants was 94.8%. The multiple Cox proportional hazard model revealed that significant risk factor of implant failure were smoking and maxillary implant (P<.05). CONCLUSION. The 10-year CSR of Implantium implants was 94.8%. Risk factors of implant failure were smoking and maxillary implant.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제49권1호
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• pp.13-20
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• 2023

Objectives: Ultra-wide implants may be used as a replacement if existing implants fail. This study was conducted to evaluate the factors influencing the prognosis and failure of ultra-wide implants. Patients and Methods: This study evaluated whether sex, age, site, diameter, length, additional surgery, implant stability (primary and secondary), and reason for ultra-wide implant placement affect the 5-year survival and success rates and marginal bone loss (MBL) of ultra-wide implants. Seventy-eight ultra-wide implants that were placed in 71 patients (39 males and 32 females) from 2008 to 2010 were studied. One-way ANOVA analysis was conducted to evaluate the statistical significance of MBL according to the patient's sex, implant site, and diameter. Independent sample t-tests were used to determine the statistical significance of MBL analysis which was used to determine the significance of the 5-year success and survival rates related to the variables. One-way ANOVA was conducted to evaluate the statistical significance of sex, implantation site, diameter, and MBL. Independent sample t-tests were used to evaluate the correlation between implantability and MBL for implantation reasons, while additional surgery, length, and Kaplan-Meier analysis were used to evaluate 5-year survival and success rates. Results: The mean age of patients was 54.2 years with a survival rate of 92.3% and a success rate of 83.3% over a mean 97.8-month period of observation. MBL averaged 0.2 mm after one year of prosthetic function loading and 0.54 mm at the time of final observation. Success rates correlated with primary stability (P=0.045), survival rates correlated with secondary stability (P=0.036), and MBL did not correlate with any variables. Conclusion: Ultra-wide implants can be used to achieve secure initial fixation in the maxillary and mandibular molar regions with poor bone quality or for alternative purposes in cases of previous implant failure.

• 대한치과보철학회지
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• 제47권4호
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• pp.424-434
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• 2009

연구목적: 임플란트는 수직교합 하중에는 비교적 잘 견디나 측방하중에 대해서는 약한 역학적 성질을 갖고 있으므로 임플란트의 재료 특성과 기하학적 형태에 따른 응력 분석 연구의 필요성이 제기되고 있다. 연구재료 및 방법: 외부육각구조를 갖는 28개의 임플란트를 7개씩 4군으로 나누어 그 제품에 적합한 UCLA gold abutment를 이용해, 제3형 금합금으로 보철 물을 제작하였고, A군 (3i, FULL $OSSEOTITE^{(R)}$-Implant), B군 (Nobelbiocare, Branemark $System^{(R)}$Mk III Groovy RP), C군 (Neobiotec, $SinusQuick^{(TM)}$ EB), D군 (Osstem, US-II)으로 분류하였다. 고정체와 지대주나사, 지대주를 연결한 후 수직적으로 절단하여 연마한 후 미세경도계를 이용하여 10군데에서 경도측정을 실시하였고, 동적하중 피로시험기를 이용하여 60-600 N범위로 파절시까지 동적 하중을 가하였다. 주사전자현미경을 이용하여 지대주나사 및 고정체의 파절 양상과 파절 위치 등을 관찰하였고, 유한요소분석을 통해 고정체와 지대주 나사에 나타나는 응력 분포와 파절면을 비교 분석하였다. 결과: 1.고정체 경도는 A, B, C, D군에서 각각 245.3, 289.7, 281.3, 300.4 Hv로 D군이 가장 높았고, A군이 가장 낮았다. 지대주 나사의 경도는 A, B, C, D군에서 각각 340.00, 317.62, 306.5, 306.2 Hv로 A군이 가장 높고, D군이 가장 낮았다. 2. 모든 실험군에서 임플란트 고정체의 파절은 응력이 집중되는 고정체 3-4번째 나사산 홈 (valley) 부위 또는 내면의 사공간부와 일치하는 부위에서 발생되었고, 피로수명은 A, B, C, D군에서 각각 31585, 47311, 30141, 105371로 D군이 가장 높았으며, A, B, C군과는 유의한 차이가 있었다(P<.05). 3. 파절양상은 B군과D군에서는 고정체와 나사 모두에서 수직 (longitudinal)파절과 수평 (transverse)파절이 동시에 일어나는 복합 (complex mode) 파절이 관찰 되었고, A와 C군에서는 고정체에서 수평 (transverse mode) 파절만이 관찰되었다. 4. 유한요소분석 결과 인장응력이 가장 높은 고정체 표면부에서 피로 균열이 시발되어 압축응력이 가장 높은 반대편 부위로 피로균열이 전파되었으며, 최대 유효 응력값은 C군이 가장 높았고, B군에서 가장 낮았다. 결론: 피질골 높이와 일치하는 임플란트 고정체 부위에서 최대 인장 주응력이 발생되며, 고정체 사공간부 (dead space)가 최대 인장 주응력이 작용하는 지그 표면과 일치할 때 피로파절이 발생되었다. 따라서 악골에 식립된 임플란트의 신뢰성을 향상시키고 수명을 증대시키기 위해서는 가능한 임플란트 주위의 골소실이 일어나지 않도록 해야 할 것이나 골흡수가 일어나 사공간부 수준까지 진행된다면 임플란트의 파절 빈도가 증가될 수 있으므로 이에 대한 대처가 필요할 것으로 사료된다.

• 대한치과의사협회지
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• 제53권5호
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• pp.298-306
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• 2015

Bacterial infection after implant installation or bone graft is a serious complication. Bone grafts represent a temporary foreign body lacking vascularisation and are therefore of increased susceptibility to infection, which may be introduced either intraoperatively or postoperatively. Bone graft-associated infections are due to biofilm formation on the surface of the bone graft and often require removal of the infected bone graft with substantial graft failure. In this review, the implant and graft related infection, the role of biofilm and the management will be discussed.

• 대한기계학회논문집A
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• 제28권7호
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• pp.940-947
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• 2004

In this paper, an optimum design problem for endosseous implant in dentistry is studied to find best implant design. An optimum design problem is formulated to reduce stresses arising at the cortical as well as cancellous bones, in which sufficient design parameters are chosen for design definition that encompasses major implants in popular use. Optimization at once (OAO) with the large number of design variables, however, causes too costly solution or even failure to converge. A concept of multilevel optimization (MLO) is employed to this end, which is to group the design variables of similar nature, solve the sub-problem of smaller size for each group in sequence, and this is iterated until convergence. Each sub-problem is solved based on the response surface method (RSM) due to its efficiency for small sized problem.

• Journal of Periodontal and Implant Science
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• 제32권3호
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• pp.577-588
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• 2002

Osseointegrated implants have been established as the standard treatment modality for full/partial edentulous patients since the 1960's, and the long term results for full edentulous patients have proven to be successful. Based on these results osseointegrated implants are now widely used for partial edentulous patients. There has been an increased interest towards the efficacy of wide implants, despite many reports mentioning the lower success rate of wide implants compared to regular implants. Recently, mandibular molar area defects are commonly restored using 2 wide implants, but it is not determined whether which treatment modality-3 regular implants or 2 wide implants-shows superior success rate. In this study, 2 wide implants and 3 regular implants used for the restoration of mandibular molar area are used to compare the survival rate of 1-4 years, and to analyze and compare the failure factors. The following conclusions could be drawn from this study. 1. Wide implants and regular implants showed 94.5% and 97,6% of survival rate respectively. After prosthodontic work, the survival rate was 100% and 98.1% for wide implants and regular implants respectively. 2. 5 failed implants have been removed. 2 wide implants and 1 regular implant have been removed due to failure of osseointegration. 1 wide implant was removed due to abscess formation caused by over-heating, and 1 regular implant was removed due to mechanical failure caused by over-loading within the first year of function. 3. No statistically significant difference was observed with respect to the amount of marginal bone loss of wide and regular implants.(P>0.05) In conclusion, restoration of the mandibular molar area using 3 regular implants was found to be a good treatment modality, and 2 wide implants could he considered a good treatment modality when success factors are taken into account.

• Journal of Periodontal and Implant Science
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• 제54권1호
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• pp.44-52
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• 2024

Purpose: This study aimed to evaluate the clinical outcomes of a single type of narrow-diameter implant (NDI) by investigating its survival rate and peri-implant marginal bone loss (MBL). In addition, variables possibly related to implant survival and MBL were investigated to identify potential risk factors. Methods: The study was conducted as a retrospective study involving 49 patients who had received 3.0-mm diameter TSIII implants (Osstem Implant Co.) at Seoul National University Dental Hospital. In total, 64 implants were included, and dental records and radiographic data were collected from 2017 to 2022. Kaplan-Meier survival curves and a Cox proportional hazard model were used to estimate the implant survival rate and to investigate the effects of age, sex, jaw, implant location, implant length, the stage of surgery, guided bone regeneration, type of implant placement, and the surgeon's proficiency (resident or professor) on implant survival. The MBL of the NDIs was measured, and the factors influencing MBL were evaluated. Results: The mean observation period was 30.5 months (interquartile range, 26.75-45 months), and 6 out of 64 implants failed. The survival rate of the NDIs was 90.6%, and the multivariate Cox regression analysis showed that age was associated with implant failure (hazard ratio, 1.17; 95% confidence interval, 1.04-1.31, P=0.01). The mean MBL was 0.44±0.75 mm, and no factors showed statistically significant associations with greater MBL. Conclusions: NDIs can be considered a primary alternative when standard-diameter implants are unsuitable. However, further studies are required to confirm their long-term stability.

• Journal of Periodontal and Implant Science
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• 제54권2호
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• pp.122-135
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• 2024

Purpose: This retrospective study aimed to assess the long-term cumulative survival rate of titanium, sandblasted, large-grit, acid-etched implants over a 10-year follow-up period and investigate the factors affecting the survival rate and change in marginal bone loss (MBL). Methods: The study included 400 patients who underwent dental implant placement at the Department of Periodontology of Seoul National University Dental Hospital (SNUDH) between 2005 and 2015. Panoramic radiographic images and dental records of patients were collected and examined using Kaplan-Meier analysis, Cox proportional hazards regression analysis, and multiple regression analysis to determine the survival rates and identify any factors related to implant failure and MBL. Results: A total of 782 implants were placed with a follow-up period ranging from 0 to 16 years (mean: 8.21±3.75 years). Overall, 25 implants were lost, resulting in a cumulative survival rate of 96.8%. Comparisons of the research variables regarding cumulative survival rate mostly yielded insignificant results. The mean mesial and distal MBLs were 1.85±2.31 mm and 1.59±2.03 mm, respectively. Factors influencing these values included age, diabetes mellitus (DM), jaw location, implant diameter, bone augmentation surgery, and prosthetic unit. Conclusions: This study found that the implant survival rates at SNUDH fell within the acceptable published criteria. The patients' sex, age, DM status, implant location, implant design, implant size, surgical type, bone augmentation, and prosthetic unit had no discernible influence on long-term implant survival. Sandblasted, large-grit, acid-etched implants might offer advantages in terms of implant longevity and consistent clinical outcomes.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제32권2호
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• pp.107-111
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• 2010

Purpose: The aim of this study is to compare the stability between Mg-incorporated implant, TiUnite and Machined implant. Materials and Methods: Premolars of 3 Mini pigs (24 months) were extracted. After 2 months later, total 27 fixtures of implants (9 of each design : Machined/ TiUnite/ Mg-incorporated) were inserted into the mandible of 3 mini-pig. Implant stability was estimated by RFA in installation to 2, 4 & 6 weeks. Statistical analysis of RFA values was performed with time and between groups using repeated measure ANOVA and turkey's multiple comparison test. Results: In analyzing the mean value for the observation periods, three types of implants yielded a slight decrease in RFA mean value after 2 week, followed by increase at 4-6 weeks. Mg incorporated oxidized implants demonstrated significantly higher RFA mean values at 6 weeks comparing other groups. The difference of RFA value with time and between groups was statistically significant. Conclusion: We concluded that Mg implants may reduce failure rates of clinical implants In the early period of bone healing and Mg implants may shorten the bone healing time from surgery to functional loading.