• Journal of Periodontal and Implant Science
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• v.38 no.4
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• pp.603-610
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• 2008

Purpose: The guided bone regeneration (GBR) technique is widely used in periradicular surgery. However, there is still some controversy regarding the effectiveness of GBR in promoting bone healing after periradicular surgery. The purpose of this study was to evaluate the resorbable membrane on the osteointegration of immediate implants in sites with periradicular lesion that had been removed by periradicular surgery. Materials and methods: Six roots of lower second premolars and 15 roots of lower third and fourth premolars of dogs were used as control and experimental teeth, respectively. Periradicular lesions were induced only in the experimental teeth. Twelve weeks later, the control and experimental teeth were extracted and implants were placed immediately. Periradicular lesions were removed with osteotomy, curettage and saline irrigation. Resorbable membranes were used in experimental group 1 but not in experimental group 2. After 12 week of healing period, the implants were clinically not mobile and showed no signs of infection. Data obtained by histomorphometric analysis were analyzed by Kruskal-Wallis test. Results: The control group showed a significantly higher bone to implant contact (BIC) ($74.14{\pm}16.18$) than experimental group 1 ($40.28{\pm}15.96$) and 2 ($48.70{\pm}17.75$)(p<0.05). However, there was no significant difference between experimental group 1 and 2. Conclusion: Although BIC in experimental groups were lower than in control group, immediate implant can be successfully placed at extraction socket with periradicular lesion and osseous defect. However, the use of resorbable membrane in bony defect created during periradicular surgery was questioned.

• Biomedical Science Letters
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• v.8 no.3
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• pp.195-202
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• 2002

Osteoarthritis (OA), the most common form of arthritis, involves the destabilization of the normal balance between the degradation and the synthesis of articular cartilage and subchondral bone within a joint. As articular cartilage degrades over time, its smooth surface roughens and bone-against-bone contact ensues, producing the inflammation response symptomatic of this 'wear and tear' disease. Although a variety of genetic, developmental, metabolic, and traumatic factors may initiate the development of osteoarthritis, its symptoms (joint pain, stiffness, and curtailed function) typically evolve slowly, and patients experience periods of relative calm alternation with episodes of inflammation and pain. Rheumatoid arthritis (RA), an autoimmune disease of unknown etiology characterized by chronic synovitis and cartilage destruction, affect 1% of the total population. Cartilage is a specialized connective tissue in which the chondrocytes occupy only 5% of the volume. Cartilage is particularly rich in extracellular matrix, with matrix making up 90% of the dry weight of the tissue chondrocytes have cell processes that extend a short distance into the matrix, but do not touch other cells thus in cartilage, cell-matrix interactions are essential for the maintenance of the extracellular matrix. In this study, subtractive hybridization method was utilized to detect genes differentially expressed in chondrocytes treated with methylprednisolone. We have isolated 57 genes that expressed differentially in the chondreocytes by methylprednisolone. 13 clones of them were analyzed with sequencing and their homologies were searched. 8 cDNAS included KIAA 0368, upregulated during skeletal muscle growth 5 (usmg 5), ribosomal protein S 18 (RPS 18), skeletal muscle ryanodine receptor, radial spoke protein 3 (RSP 3), ribosomal protein QM, ribosomal protein L37a (RPL37A), cytochrome coxidase subunit VIII (COX8).

• The Journal of Advanced Prosthodontics
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• v.9 no.1
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• pp.31-37
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• 2017

PURPOSE. The purpose of this study was to analyze the influence of the platform switching concept on an implant system and peri-implant bone using three-dimensional finite element analysis. MATERIALS AND METHODS. Two three-dimensional finite element models for wide platform and platform switching were created. In the wide platform model, a wide platform abutment was connected to a wide platform implant. In the platform switching model, the wide platform abutment of the wide platform model was replaced by a regular platform abutment. A contact condition was set between the implant components. A vertical load of 300 N was applied to the crown. The maximum von Mises stress values and displacements of the two models were compared to analyze the biomechanical behavior of the models. RESULTS. In the two models, the stress was mainly concentrated at the bottom of the abutment and the top surface of the implant in both models. However, the von Mises stress values were much higher in the platform switching model in most of the components, except for the bone. The highest von Mises values and stress distribution pattern of the bone were similar in the two models. The components of the platform switching model showed greater displacement than those of the wide platform model. CONCLUSION. Due to the stress concentration generated in the implant and the prosthodontic components of the platform switched implant, the mechanical complications might occur when platform switching concept is used.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.2
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• pp.70-76
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• 2017

The purpose of this study was to perform a literature review of short implants in the posterior maxilla and to assess the influence of different factors on implant success rate. A comprehensive search was conducted to retrieve articles published from 2004 to 2015 using short dental implants with lengths less than 10 mm in the posterior maxilla with at least one year of follow-up. Twenty-four of 253 papers were selected, reviewed, and produced the following results. (1) The initial survival rate of short implants in the posterior maxilla was not related to implant width, surface, or design; however, the cumulative success rate of rough-surface short implants was higher than that of machined-surface implants especially in performance of edentulous dental implants of length <7 mm. (2) While bone augmentation can be used for rehabilitation of the atrophic posterior maxilla, short dental implants may be an alternative approach with fewer biological complications. (3) The increased crown-to-implant (C/I) ratio and occlusal table (OT) values in short dental implants with favorable occlusal loading do not seem to cause peri-implant bone loss. Higher C/I ratio does not produce any negative influence on implant success. (4) Some approaches that decrease the stress in posterior short implants use an implant designed to increase bone-implant contact surface area, providing the patient with a mutually protected or canine guidance occlusion and splinting implants together with no cantilever load. The survival rate of short implants in the posterior edentulous maxilla is high, and applying short implants under strict clinical protocols seems to be a safe and predictable technique.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.3
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• pp.339-344
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• 2007

Statement of problem. Various anodic oxidation techniques can be applied to dental implant surfaces. But the condition for optimal anodized surfaces has not been described yet. Purpose. The purpose of this investigation was to compare an implant that was oxidized by another method with $TiUnite^{TM}$ through resonance frequency analysis and histomorphometry. Material and methods. Turned (control), $TiUnite^{TM}$ and another oxidized fixtures, which used $Ca^{2+}$ solution for anodic oxidation, were placed in the tibiae of 5 New Zealand White rabbits. The bone responses were evaluated and compared by consecutive resonance frequency analysis once a week for 6 weeks and histomorphometry after a healing period of 6 weeks. Results. At the first week, both oxidized implants showed significantly higher implant stability quotient (ISQ) values than the control. No significant differences in resonance frequency analysis were found between the two oxidized groups for 6 weeks. The means and standard deviations of bone-to-implant contact (BIC) ratios were $71.0{\pm}4.2$ for $TiUnite^{TM}$, $67.5{\pm}10.3$ for the $Ca^{2+}$-based oxidation fixture, $22.8{\pm}6.5$ for the control. Both oxidized implants were significantly superior in osseointegration to the turned one. There was, however, no statistically significant difference between the two oxidized implants. Conclusion. $TiUnite^{TM}$ and the $Ca^{2+}$-based oxidation fixture showed superior early bone response than the control with respect to resonance frequency analysis and histomorphometry. No significant differences between the oxidized groups, however, were found in this investigation using the rabbit tibia model.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.6
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• pp.518-528
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• 2008

Purpose: The long-term experience of using osseointegrated implants for prosthetic rehabilitation of the edentulous patients shows that high success rates can be predictably achieved. Primary implant stability has been identified to be a prerequisite to achieve osseointegration. In this study, we set up the amount of removed bone so that it differed on implant installation site for each group. The influence of each initial stability on secondary stability and osseointegration was compared with time lapse using resonance frequency analysis and histomorphometric analysis. Materials and methods: A total 27 US $II^{(R)}$ (Osstem, Korea) implants were placed in the mandibular edentulous area of 3 beagle dogs. The implant site was prepared by the conventional technique with drills, and three experimental groups were divided into under-drilling group, normal-drilling group and over-drilling group. The Implant Stability Quotient (ISQ) was measured at intervals of immediately, 4, 8, 12 weeks after placement using $Osstell^{(R)}$ mentor RFA. After the animals were sacrificed, histomorphometric evaluation was executed for measuring BIC and BD. Results: 1) The under-drilled group showed most high ISQ value for whole experiment period. 2) Bone-to-implant-contact(BIC) showed the tendency to be increased gradually as the experiment period passed except the 8 weeks of the normal group. 3) The under-drilled group showed most high bone density(BD) level for whole experiment period, and it was expressed the aspect to be increased gradually according to an experiment period passage in the average of all group. 4) Resonance frequency analysis and histomorphometric analysis are presumed by generally proportional. Conclusions: As this research result, it seems that there are some correlation between resonance frequency analysis and histomorphometric analysis. As are accomplished osseointegration stably so that more superior at the region which the overpressure comes to add, it will be applicable method in clinical field.

• Journal of Periodontal and Implant Science
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• v.28 no.3
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• pp.401-408
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• 1998

Screw shaped implants of Titanium-13Zirconium-6Niobium(newly developed), Titanium-6Zirconium-6Sn-6Niobium(newly developed) and Titanium-6Aluminum-4Vanadium were machined with square top and inserted in rabbit bone for 3 months. Biomechanical tests(removal torque) showed Titanium-13Zirconium-6Niobium and Titanium-6Zirconium-6Sn-6Niobium to be more stable in the bone bed than those of Titanium-6Aluminum-4Vanadium. Titanium-13Zirconium-6Niobium implants demonstrated a mean removal torque of 31.59Ncm while Titanium-6Aluminum-4Vanadium demonstrated a mean removal torque of 25.27Ncm and Titanium-6Zirconium-6Sn-6Niobium revealed a mean removal torque of 37.44Ncm and were statistically significance in Wilcoxon Signed Rank test(P<0.05). Histomorphometrical comparisons were performed on $10\;{\mu}m$ thick undecalcified ground sections in the light microscope and Titanium-13Zirconium-6Niobium showed more mean bone-tometal contact ratio than to other twotitanium alloys but had no statistically significant differences were found among the three materials(P>0.01).

• 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.

• Korean Journal of Applied Biomechanics
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• v.29 no.3
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• pp.145-155
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• 2019

Objective: The purpose of this study was to compare the physical characteristics (bone mineral density, joint muscle strength) and running biomechanics between older adults and young adult runners to understand the changes of running strategy by aging. Method: Bone mineral density (Dual Energy X-ray Absorptiometry, USA) of lower lower extremity and muscle strength (Cybex Humac Norm [DEXA], CSMI, USA) were measured to identify the physical characteristics of 10 elderly (age: $67.70{\pm}3.30yrs$, height: $1.68{\pm}0.04m$, mass: $67.70{\pm}3.80kg$) and 10 young adults (age: $21.20{\pm}0.42yrs$, height: $1.73{\pm}0.06m$, mass: $72.11{\pm}4.15kg$). Running data was collected by using an instrumented treadmill (Bertec, USA) and 7 infrared cameras (Oqus 300, Qualisys, Sweden). Two-way repeated ANOVA analysis was used to analyze results at a significant level of .05 with Bonferroni post hoc analysis. Results: Compared to the young adult group, the elderly group showed statistically significant difference in physical characteristics and in running characteristics. Elderly runners showed lower BMD and muscle strength compared with young runners (p<.05). In the running parameters, elderly runners tend to show shorter contact time and stride length compared with young runners (p<.05). In the joint angles, elderly runners showed smaller range of ankle motion compared with young runners (p<.05). Finally, elderly runners showed lower level of joint moment, joint power, and GRF compared with young runners in each running speed (p<.05). Conclusion: The running behavior of the elderly performed periodic running was similar to many variables of young adults. However, there were noticeable differences found in the ankle joints and most kinetic variables compared with young adult runners. This discrepancy may propose that elderly runners should consider appropriate running distance and intensity in the program.

• Journal of Yeungnam Medical Science
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• v.36 no.1
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• pp.43-49
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• 2019

Background: In the osseointegration of dental implants, the implant surface properties have been reported to be some of the most important critical factors. The effect of implant's surfaces created by resorbable blast media (RBM) followed by laser ablation on bone tissue reactions was examined using the removal torque test and histomorphometric analysis. Methods: Two types of dental implants, RBM-laser implants (experimental group) and RBM implants (control group) (CSM implant system, Daegu, Korea; L=6 mm, diameter=3.75 mm) were placed into the right and left distal femoral metaphysis of 17 adult rabbits. Six weeks after placement, removal torque was measured and histomorphometric analysis was performed. Results: The mean removal torque was $24.0{\pm}10.2Ncm$ and $46.6{\pm}16.4Ncm$ for the control and test specimens, respectively. The experimental RBM-laser implants had significantly higher removal torque values than the control RBM implants (p=0.013). The mean values of total and cortical bone to implant contact (BIC) were respectively $46.3{\pm}10.8%$ and $65.3{\pm}12.5%$ for the experimental group, and $41.9{\pm}18.5%$ and $57.6{\pm}10.6%$ for the control group. The experimental RBM-laser implants showed a higher degree of total and cortical BIC compared with RBM implants, but there was no statistical significance (p=0.482, 0.225). Conclusion: The removal torque and BIC of the test group were higher than those of the control group. In this study, the surface treatment created by RBM treatment followed by laser ablation appears to have a potential in improving bone tissue reactions of dental implants.