• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.5
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• pp.417-427
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• 2008

The aim of this study is to investigate the effect of anodizing surface to osseointegration of implant by using of resonance frequency analysis (RFA), quantitative and qualitative assessment of an anodically modified implant type with regard to osseous healing qualities. A total of 96 screw-shaped implants were prepared for this study. 72 implants were prepared by electrochemical oxidation with different ways. 24 (group 1 SP) were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid. 24 (group 2GC) were prepared at galvanostatic mode in calcium glycerophosphate and calcium acetate and 24 (group 3 CMP (Calcium Metaphosphate) Coating were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid followed by CMP coating. Rest of 24 (control group were as a control group of RBM surface. Bone tissue responses were evaluated by resonance frequency analysis (RFA) that were undertaken at 2, 4 and 6 weeks after implant placement in the mandible of mini-pig. Group 1 SP (anodized with sulfuric acid and phosphoric acid implants) demonstrated slightly stronger bone responses than control Group RBM. Group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) demonstrated no difference which were compared with control group. Group 3 GMP (anodized and CMP coated implants) demonstrated slightly stronger and faster bone responses than any other implants. But, all observation result of RF A showed no significant differences between experimental groups with various surface type. Histomorphometric evaluation demonstrated significantly higher bone-to-implant contact for group 2 GC. Significantly more bone formation was found inside threaded area for group 2 GC. It was concluded that group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) showed more effects on the bone tissue responses than RBM surface in initial period of implantation. In addition, CMP showed a tendency to promote bone tissue responses.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.5
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• pp.335-339
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• 2009

The purpose of this study was to evaluate clinical and radiographic changes of regular diameter implants placed in the posterior region. A total of 47 standard diameter implants were consecutively placed in the posterior region of 20 partially edentulous patients. The diameters of the implants were 4.1mm (N=35, 74%) and 4.3mm (N=12, 26%), respectively. Peri-implant bone loss and clinical parameters such as mobility, suppuration, swelling, bleeding on probing (BOP) were evaluated at the baseline and?the final follow-up visit. The age of the patients ranged between 24~82 years (mean age: 54.7 years). The cumulative survival rate of the regular diameter implants loaded for a period of 3-24 months (Mean: $11.7{\pm}7.9$ month) was 100%. The average bone loss over the follow-up was $0.36{\pm}0.67\;mm$. Success rate was 95.7%. Only two implants failed (bone loss exceeding 1mm after 1 year of placement). Some prosthetic complications occurred, such as screw loosening (N=1) and dissolution of cementation material (N=2). The present study describes successful outcome following the use of standard-diameter-implants placed in the posterior region, and further comprehensive maintenance practices and follow-up schedules are required.

• The Journal of Advanced Prosthodontics
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• v.3 no.4
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• pp.204-215
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• 2011

PURPOSE. The aim of this retrospective study is to analyze the relationship between local factors and survival rate of dental implant which had been installed and restored in Seoul Veterans Hospital dental center for past 10 years. And when the relationship is found out, it could be helpful to predict the prognosis of dental implants. MATERIALS AND METHODS. A retrospective study of patients receiving root-shaped screw-type dental implants placed from January 2000 to December 2009 was conducted. 6385 implants were placed in 3755 patients. The following data were collected from the dental records and radiographs: patient's age, gender, implant type and surface, length, diameter, location of implant placement, bone quality, prosthesis type. The correlations between these data and survival rate were analyzed. Statistical analysis was performed with the use of Kaplan-Meier analysis, Chi-square test and odds ratio. RESULTS. In all, 6385 implants were placed in 3755 patients (3120 male, 635 female; mean age $65{\pm}10.58$ years). 108 implants failed and the cumulative survival rate was 96.33%. There were significant differences in age, implant type and surface, length, location and prosthesis type (P<.05). No significant differences were found in relation to the following factors: gender, diameter and bone quality (P>.05). CONCLUSION. Related factors such as age, implant type, length, location and prosthesis type had a significant effect on the implant survival.

• The korean journal of orthodontics
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• v.48 no.5
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• pp.283-291
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• 2018

Objective: This study was conducted to perform histomorphometric evaluations of the bone surrounding orthodontic miniscrews according to their proximity to the adjacent tooth roots in the posterior mandible of beagle dogs. Methods: Four male beagle dogs were used for this study. Six orthodontic miniscrews were placed in the interradicular spaces in the posterior mandible of each dog (n = 24). The implanted miniscrews were classified into no loading, immediate loading, and delayed loading groups according to the loading time. At 6 weeks after screw placement, the animals were sacrificed, and tissue blocks including the miniscrews were harvested for histological examinations. After analysis of the histological sections, the miniscrews were categorized into three additional groups according to the root proximity: high root proximity, low root proximity, and safe distance groups. Differences in the bone-implant contact (BIC, %) among the root proximity groups and loading time groups were determined using statistical analyses. Results: No BIC was observed within the bundle bone invaded by the miniscrew threads. Narrowing of the periodontal ligament space was observed in cases where the miniscrew threads touched the bundle bone. BIC (%) was significantly lower in the high root proximity group than in the low root proximity and safe distance groups. However, BIC (%) showed no significant differences among the loading time groups. Conclusions: Regardless of the loading time, the stability of an orthodontic miniscrew is decreased if it is in contact with the bundle bone as well as the adjacent tooth root.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.42 no.3
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• pp.139-143
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• 2016

Objectives: If teeth are missing, super-eruption of teeth in the opposing arch can occur in the area and can change the occlusal plane. When missing teeth are replaced with implants, the oral surgeon must determine whether or not the super-erupted teeth need to be treated in order to normalize the occlusal plane. In this study, we evaluated the clinical prognosis of dentition after implant placement and prosthetic treatment were completed in an occlusal plane altered by super-erupted teeth in the opposing arch without additional treatment of the super-erupted teeth. Materials and Methods: Twenty-two patients (9 males, 13 females) were treated with implants and prosthetics without addressing the super-erupted opposing dentition from April 2004 to August 2012 at Seoul National University Bundang Hospital. A total of 33 implants were placed. Values of crestal bone loss, survival rates, and surgical and prosthetic complications for an average of 29.6 months after prosthetic loading were recorded. Results: In one case, the cover screw was exposed after implant surgery. The mean crestal bone loss was $0.09{\pm}0.30mm$. Of the 33 implants, 31 survived, a survival rate of 93.94%. A prosthetic complication occurred in one case but functioned well after correction. Conclusion: Favorable clinical results from prosthetic complications, crestal bone loss, and implant survival rates were exhibited in implants next to a super-erupted opposing tooth.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.1
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• pp.98-129
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• 1995

The purpose of this study was to evaluate how mandibular implant-supported fixed complete prosthesis, implant and mandible responded mechanically, according to curvature of arch, number and location of fixture, and amounts of load. The shape of mandibular arch was tapered or square form and, 4 or 6 fixtures were implanted in each arch model. A vertical load of 10kg was applied at the center of prosthesis and a vertical load of 20kg was applied at the location of the 10mm or 20mm cantilever posterior to the most distal implant. Three-dimensional finite element analysis was performed for stress distribution and deflection using commercial software(ABAQUS program) for Sun-SPARC Workstation. The results were as follows : 1. The case square arch form was more stable to compare with that of tapered arch form in respect of stress distribution and displacement under vertical load on the center of prosthesis. 2. 6-implants cases were more stable than 4-implants cases for decreasing bending torque under vertical load on the center of prosthesis. 3. Under vertical load on cantilever extension, the case of 10mm long cantilever was more stable than that of 20mm long cantilever in respect of stress distribution and displacement. 4. Under vertical load on cantilever extension, 6-implants cases had a tendency to reduce displacement and to increase the reaction force of supporting point due to increasing of the bending stiffness of the prosthesis than 4-implant case. 5. When the ends of 10mm or 20mm long cantilever were loaded, the most distal implant was under compressive stress but the second most distal implant was under the highest tensile stress and the remaining implants were under varying tensile stress. 6. Because 6-implants cases had smaller displacement than 4-implants cases, 6-implants cases were more favorable in respect of prevention of screw loosening under repeated loadings.

• The Journal of Advanced Prosthodontics
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• v.1 no.1
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• pp.10-18
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• 2009

STATEMENT OF PROBLEM. Despite an improved bone reactions of Mg-incorporated implants in the animals, little yet has been carried out by the experimental investigations in functional loading conditions. PURPOSE. This study investigated the clinical and histologic parameters of osseointegrated Mg-incorporated implants in early loading conditions. MATERIAL AND METHODS. A total of 36 solid screw implants(diameter 3.75 mm, length 10 mm) were placed in the mandibles of 6 beagle dogs. Test groups included 18 Mg-incorporated implants. Turned titanium implants served as control. Gold crowns were inserted 4 weeks after implant placement and the dogs were immediately put on a food diet. Implants were observed for 10 weeks after loading. Radiographic assessments and stability tests were performed at the time of fixture installation, $2^{nd}$ stage surgery, 4 weeks after loading, and 10 weeks after loading. Histological observations and morphometrical measurements were also performed. RESULTS. Of 36 implants, 33 displayed no discernible mobility, corresponding to successful clinical function. There was no statistically significant difference between test implants and controls in marginal bone levels(P=.46) and RFA values. The mean BIC % in the Mg-implants was $54.5{\pm}8.4%$. The mean BIC % in the turned implant was $45.3{\pm}12.2%$. These differences between the Mg-implant and control implant were statistically significant(P=.005). CONCLUSIONS. The anodized, Mg-incorporated implant demonstrated significantly more bone-to-implant contact(BIC) in early loading conditions. CLINICAL IMPLICATIONS. The results of this study in beagle dogs suggest the possibility of achieving predictable stability of early loaded free-standing dental implants with Mg-incorporated surface.

• The Journal of Advanced Prosthodontics
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• v.4 no.4
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• pp.227-234
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• 2012

PURPOSE. The aims of this pilot study were to introduce implant loading devices designed for animal study and to evaluate the validity of the load transmission ability of the loading devices. MATERIALS AND METHODS. Implant loading devices were specially designed and fabricated with two implant abutments and cast metal bars, and orthodontic expansion screw. In six Beagles, all premolars were extracted and two implants were placed in each side of the mandibles. The loading device was inserted two weeks after the implant placement. According to the loading protocol, the load was applied to the implants with different time and method, simulating early, progressive, and delayed loading. The implants were clinically evaluated and the loading devices were removed and replaced to the master cast, followed by stress-strain analysis. Descriptive statistics of remained strain (${\mu}{\varepsilon}$) was evaluated after repeating three cycles of the loading device activation. Statistic analysis was performed using nonparametric, independent t-test with 5% significance level and Friedman's test was also used for verification. RESULTS. The loading devices were in good action. However, four implants in three Beagles showed loss of osseointegration. In stress-strain analysis, loading devices showed similar amount of increase in the remained strain after applying 1-unit load for three times. CONCLUSION. Specialized design of the implant loading device was introduced. The loading device applied similar amount of loads near the implant after each 1-unit loading. However, the direction of the loads was not parallel to the long axis of the implants as predicted before the study.

• Anatomy and Cell Biology
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• v.57 no.2
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• pp.221-228
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• 2024

Although studies of the sacral corridor dimension have been reported in the European population, little attention has been paid to this issue in the Asian population. The purpose of the study is to estimate the safe dimension of the corridor to avoid neurovascular damage during the fixation of the sacral fracture. The study aimed to examine the cephalocaudal (vertical) and the anteroposterior diameter of the bony passage in the upper three sacral segments. The study further examines the effect of age and sex on corridor dimensions at different sacral levels. Three-dimensionally reconstructed sacra from computed tomography of normal subjects were included in the study. Cephalocaudal and anteroposterior diameters were measured in coronal and axial sections using Geomagic Freeform Plus software. Anteroposterior diameter of the sacral corridor at the first, second, and third sacral segments are significantly higher in males (P=0.013, 0.0011, and <0.0001, respectively). The length of the sacrum also revealed sexual dimorphism (P<0.00016). The anteroposterior diameter of the second sacral segment (ap-S2c) correlated moderately with the first sacral anteroposterior diameter (ap-S1c) (R=0.519, P<0.001). The ap-S2c exhibited a moderate correlation to the third sacral segment (ap-S3c) (R=0.677, P<0.001). The sacral corridor at the level of S1 has the largest cephalocaudal (18.25 mm) and anteroposterior diameter (17.11 mm). Placement of the screw in the first sacral corridor may avoid damage to the neurovascular bundle during the fixation of the sacral fracture.

• Journal of Korean Neurosurgical Society
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• v.30 no.7
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• pp.883-890
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• 2001

Objectives : An in vitro biomechanical study of posterior lumbar interbody fusion(PLIF) with threaded cage using two different approaches was performed on eighteen functional spinal units of bovine lumbar spines. The purpose of this study was to compare the segmental stiffnesses among PLIF with one long posterolateral cage, PLIF with one long posterolateral cage and simultaneous facet joint fixation, and PLIF with two posterior cages. Methods : Eighteen bovine lumbar functional spinal units were divided into three groups. All specimens were tested intact and with cage insertion. Group 1(n=12) had a long threaded cage($15{\times}36mm$) inserted posterolaterally and oriented counter anterolaterally on the left side by posterior approach with left unilateral facetectomy. Group 2(n=6) had two regular length cages($15{\times}24mm$) inserted posteriorly with bilateral facetectomy. Six specimens from group 1 were then retested after unilateral facet joint screw fixation in neutral(group 3). Likewise, the other six specimens from group 1 were retested after fixation with a facet joint screw in an extended position(group 4). Nondestructive tests were performed in pure compression, flexion, extension, lateral bending, and torsion. Results : PLIF with a single cage, group 1, had a significantly higher stiffnesses than PLIF with two cages, group 2, in left and right torsion(p<0.05). Group 1 showed higher stiffness values than group 2 in pure compression, flexion, left and right bending but were not significantly different. Group 3 showed a significant increase in stiffness in comparison to group 1 for pure compression, extension, left bending and right torsion(p<0.05). For group 4, the stiffness significantly increased in comparison to group 1 for extension, flexion and right torsion(p<0.05). Although there was no significant difference between groups 3 and 4, group 4 had increased stiffness in extension, flexion, right bending and torsion. Conclusion : Posterior lumbar interbody fusion with a single long threaded cage inserted posterolaterally with unilateral facetectomy enables sufficient decompression while maintaining a majority of the posterior elements. In combination with a facet joint screw fixation, adequate postoperative stability can be achieved. We suggest that posterolateral insertion of a long threaded cage is biomechanically an ideal alternative to PLIF.