• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.392-401
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• 2010

Introduction: Diabetes mellitus, as a major health problem for the elderly has been shown to alter the properties of the bone and impair bone healing around a titanium implant in both humans and animals. The aim of this study was to examine the effect of adipose-derived stem cells on the healing process around a titanium implant in streptozotocin-induced diabetic rats. Materials and Methods: Thirteen rats were divided into two groups: adipose-derived stem cells injected group and a control group. A titanium screw implant (diameter: 2.0 mm, length: 3.5 mm) was placed into both tibia of 13 rats: 13 right tibia as the control group and 13 left tibia as the experimental group. The rats were sacrificed at different intervals (1, 2, and 4 weeks) after implantation for histopathology observations and immunohistochemistric analysis. Results: The histopathological findings revealed earlier new formed bone in the experimental group than the control group. In particular, at 1 week after implantation, the experimental group showed more newly formed bone and collagen around the implant than the control group. In immunohistochemistric analysis, osteoprotegerin (OPG) expression in the experimental group increased early compared to that of the control group until 2 weeks after implantation. However, after 2 weeks, OPG expression in the experimental group was similar to OPG expression in the control group. The receptor activator of nuclear factor ${\kappa}B$ ligand (RANKL) expression in the experimental group increased early compared to that of the control group, and then decreased at 2 weeks. After 2 weeks, the level of RANKL expression was similar in both groups. Conclusion: These results suggest that adipose-derived stem cells in implantation can promote bone healing around titanium, particularly in diabetes mellitus induced animals.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.148-169
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• 1994

The concept of biologic attachment of load-bearing implants has developed over the past decades as an alternative to the difficulties associated with long term implantation using mechanical fixation and bone cement. The choice of implant material is also as critical an element as site preparation or insertion procedure. The properties of implants that affect host tissue responses are not limited to chemical composition alone, but also include shape, surface characteristics, site of implantation, and mechanical interaction with host tissues. Initial mechanical interlocking prevents micromotion and may be a prerequisite for direct bone apposition. A hard tightening of screws does not necessarily mean a stronger fixation and final tightening of the fixtures is dependent on the experience of the operator. Removal torque is lower than insertion torque. The purpose of this study was to investigate differences in the removal torques at the bone-implant interface of polished and sandblasted Titanium. This experiment will give insight into important factors that must be considered when interpreting in vivo screwing forces on implants during the connection of the transmucosal abutments. We evaluated the significance of different surface textures by comparison of the withdrawal forces necessary for removal of otherwise identical rough and polished implants of Titanium and also evaluated interfacial response on the light microscopic level to implant surface. And the priority of the area of insertion on osseointegration were evaluated. 9 Titanium implants - among them, 3 were for the developmental - of either a smooth or rough surface finish were inserted in the dog mandible in the right side. 3 months later Kanon Torque Gauge was used to unscrew the implants. The results were as follows : 1. No significant difference was seen in the removal torque due to variation in surface treatment, 23 Ncm for the sandblasted and 23.33 Ncm for the polished surface (p>0.05). 2. Implants in the anterior (25 Ncm) mandible showed better resistance to unscrewing in comparison to ones in the posterior (18 Ncm) region (p<0.05). 3. Developmental fixtures (22 Ncm) had similar pullout strength to the control group (p>0.05).

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.1-28
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• 1990

The severe atrophic edentulism with poor neuromuscular control militates against successful conventional denture therapy. To such situation, a prescribing of dental implant treatment has been considered with some probability. Implant materials used as a trial for dental implants includes metals, plastic polymers and ceramics. The purpose of this study was to observe histologic response in osseointegration process at titanium implant-tissue interface based on biocompatibility at specific period of sequential natures which were divided into a half month, one, month, two months, three months and immediate as a base line. In this study, unilateral lower left premolar and molar teeth were extraced in three dogs. After allowing to heal for 6 months, three kinds of osseointegrated implant, $Br{\aa}nemark$, Corevent and kimplant(a prototype of SNU implant study)were inserted in each dog respectively according to the above sequence from front to back. The specimens were taken from those dogs at the same time since implant were inserted quite reverse order of the specified periods, and decalcified and processed for histologic examination for the light microscopy and the electron microscopy. The microscopic histologic findings at the interface between titanium implants and tissue were interpretated as follows : A. Light microscopic findings : a. Immediate : Implant were surrounded by compact bone and spongy bone. Microcrak was observed in the superficial bone tissue. Osteocytes were disappeared and bone lacunae were observed as a vacant space in some parts. In the contacting with the spongy bone, bone trabeculae and bone marrow were in contact with the implant. b. A half Month : Osteoblasts exist as a monolayer in th inner bone trabeculae and do bone additiocn. Osteoblasts&inflammatory cells were observed in some parts. c. One Month : The presence of osteoclasts decreased. Osteoblasts did active bone fromation, and bone marrow was in contact with the implant in the many places. d. Two Months : Bone formation was advanced in comparison with the b and c. The presence of osteoclsts was not observed. e. Three Months : The superficial bone tissue contacted with the implants was entirely composed by the compact bone. B. Electron microscopic findings : a. A half month and one month group : In the parts of the active bone formation, osteoblasts with the well developed endoplasmic reticulum and Golgi apparatus were arranged in the monolayer. In the parts of the bone resorption, ruffled border was well developed and many osteoclasts with the well-developed golgi apparatus, mitochondria, vacuole, vesicle and lysosome were existed. b. Three months group : No osteoblasts were observed in the superficial bone tissue. Bone matrix with collaen fiber was observed. c. No significant dirrerence in the histologic findings was observed in $Br{\aa}nemark$, Core-vent and kimplant.

• The Journal of Korean Academy of Prosthodontics
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• v.29 no.2
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• pp.225-243
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• 1991

In recent years immediate implantation has been tried by a few clinicians. This study placed IMZ implants in the rabbit femur with and without bony defects around the implant for simulating fresh extraction site. And one group with bony defects used porous hydroxyapatite ganules(HA) to fill if and the other group left the bony defects around the implant. The purpose of this study was to compare the shear bond strength and the bony contact and formation around the implant. Fifteen rabbits were divided into three groups and placed 10 IMZ implants to each group. Implant sites were surgically prepared with IMZ drills kit and implants were placed(Control), artificial bony defect was created with Apaceram drills kit around the implant sites and implants were placed(Experimental I), bony defect was filled with porous hydroxyapatite granules(Experimental II). Thereafter, rabbits were sacrificed at 8th week and specimens were prepared and pushout tested for shear bond strength of bone-implant interface immediately. Undecalcified and decalcified specimens were prepared with Vilanueva and hematoxylin-eosin stain for light microscopic finding. The results of this study were as follows. 1. In the control group, mean shear strength of bone-implant interface was $2.614{\pm}0.680$ MPa, experimental I was $0.664{\pm}0.322$ MPa, and experimental II was $2.281{\pm}0.606$ MPa. There was significant difference between control and experimental I, between experimental I and experimental II, but did not show significant difference between control and experimental II statistically. 2. In the bony formation surrounding IMZ implant of the three groups, that of cortical bone is more advanced than cancellous bone area. 3. In the histological findings of undecalcified specimens, control and experimental II showed more than 50% of bony or osteoid formation at the bony-implant interface. 4. In the histological findings of undecalcified specimens, experimental I showed less than 50% of bony or osteoid formation at the interface, and observed partial bony defect in the coronal zone. 5. In the experimental II group, were observed direct bony contact to hydroxyapatite granules, and infiltration of a few giant cells. 6. No inflammatory responses were seen around the titanium implants and the hydroxyapatite granules.

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.110-118
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• 2004

The corrosion of pure titanium (CP- Ti Grade 2) and titanium alloy (Ti6Al4V ELI) were studied under various conditions of simulated body fluids. The static immersion test and the electrochemical test were performed in accordance with ISO 10271 : 2001. For the electrochemical test, the open circuit potential was monitored as a function of time, and the cyclic polarization curve was recorded. The corrosion resistance was evaluated from the values of corrosion potential, passivation current density, breakdown potential, and the shape of hysteresis etc. The effects of alloy type, surface condition, temperature, oxygen, and constituents in the fluids such as acid, chloride were estimated. Both specimens had extremely low dissolution rate in the static immersion test. They showed strong passivation characteristics in the electrochemical test. They maintained negligible current density throughout the wide anodic potential range. The passive layer was not broken up to 2.0 V (vs. SCE). The hysteresis and the shift of passivation potential toward the anodic direction was observed during the reversed scan. The passivation process appeared to be accelerated by oxygen in air or that dissolved in the fluids. The passivation also proceeded without oxygen by the reaction of constituents in the fluids. Acid or chloride in the fluids, specially later weakened the passive layer, and then induced higher passivation current density and less shift of passivation potential in the reversed scan. CP-Ti Grade 2 was more reactive than Ti6Al4V ELI in the fluids containing acid or chloride, but thicker layer produced on its surface provided higher corrosion resistance.

• Applied Science and Convergence Technology
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• v.25 no.3
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• pp.51-55
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• 2016

The surface treatment of a titanium implant is investigated with a non-thermal atmospheric pressure plasma jet. The plasma jet is generated by the injection of He and $O_2$ gas mixture with a sinusoidal driving voltage of 3 kV or more and with a driving frequency of 20 kHz. The generated plasma plume has a length up to 35 mm from the jet outlet. The wettability of 4 different titanium surfaces with plasma treatments was measured by the contact angle analysis. The water contact angles were significantly reduced especially for $O_2/He$ mixture plasma, which was explained with the optical emission spectroscopy. Consequently, plasma treatment enhances wettability of the titanium surface significantly within the operation time of tens of seconds, which is practically helpful for tooth implantation.

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.337-350
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• 1998

The purpose of this' study was to compare surface roughness and morphologic changes after use of various plaque control devices to titanium implant surfaces. The study materials were 6 ITI titanium implants($Bonefit^{(R)}$) and 5 plaque control devices. 6 implants were divided into 6 different groups and instrumented by each plaque control devices as follows. 1) Group I : untreated control 2) Group II : Titanium curette(Titanium $curette^{(R)}$, 3i) 80 vertical/horizontal strokes 3) Group III : Plastic curette($Implacare^{(R)}$, Hu-Friedy) 80 vertical/horizontal strokes 4) Group N : Plastic tip-ultrasonic scaler($Amdent^{(R)}$, Amdent) 160 seconds 5) Group V : Rotating interdental brush($Identobrush^{(R)}$, Identoflex) 160 seconds 6) Group VI : Abrasive rubber cup polisher($Zircate^{(R)}$, Prophy paste, Dentsply) 160 sec-onds. All specimens were prepared for evaluation by surface roughness tester, optical stereomicroscopy(OM) and scanning electron microscopy(SEM). The Ra and Rt mean values of the tested specimens were 1) Group I ($Ra=0.170{\pm}0.007{\mu}m$, $Rt=1.297{\pm}0.016{\mu}m$) 2) Group II ($Ra=0.209{\pm}0.006{\mu}m$, $Rt=1.602{\pm}0.110{\mu}m$) 3) Group III ($Ra=0.179{\pm}0.001{\mu}m$, $Rt=1.429{\pm}0.055{\mu}m$) 4) Group IV ($Ra=0.182{\pm}0.005{\mu}m$, $Rt=1.511{\pm}0.085{\mu}m$) 5) Group V ($Ra=0.301{\pm}0.008{\mu}m$, $Rt=1.882{\pm}0.131{\mu}m$) 6) Group VI ($Ra=0.147{\pm}0.010{\mu}m$, $Rt=1.059{\pm}0.021{\mu}m$) In Ra values, experimental group II, V, VI were statistically significant different when compared with control. OM and SEM observation showed that experimental group III, IV were minimal changes when compared with control and group VI was smoothest among other experimental groups. The results suggested that plastic curette and plastic tip-ultrasonic scaler were predictable devices to titanium implant surface.

• Journal of Korean Neurosurgical Society
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• v.37 no.3
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• pp.217-222
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• 2005

Objective: To achieve optimal fit of implant, it is necessary to bend the implant during spine surgery. Bending procedure may decrease stiffness of plate especially made of titanium and stainless steel. Typically titanium suffers adverse effects including early crack propagation when it is bent. We investigate whether 6 degree bending of titanium plates would decrease the stiffness after full cyclic loading by comparing with non-bending titanium plates group. Methods: Authors experimented 40 titanium alloy plates of 57mm in length, manufactured by 5 different companies. Total 40 plates were divided into two groups (20 bent plates for experimental group and 20 non-bent plates for control group). Twenty plates of experimental group were bent to 6 degree with 3-point bending technique and verified with image analyzer. Using the electron microscope, we sought for a initial crack before and after 3-point bending. Mechanical testing by means of 6000 cyclic axial-compression loading of 35N in compression with moment arm of 35mm-1.1 Nm was conducted on each plate and followed by the electron microscopic examination to detect crack or fissure on plates. Results: The stiffness was decreased after 6000 cyclic loading, but there was no statistically significant difference in stiffness between experimental and control group. There was no evidence of change in grain structure on the electron microscopic magnification. Conclusion: The titanium cervical plates can be bent to 6 degree without any crack or weakness of plate. We also assume that minimal bending may increase the resistance to fatigue fracture in cervical flexion-extension movement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.17-18
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• 2010

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.4
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• pp.307-314
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• 2005

After dental implant are planted into their bony site among the various growth factors associated with bone formation. BMP is expressed in the bone surrounding the implant fixture. By taking a close look at BMP2, BMP4 which are growth factors that take put in bone formation, its histologic features and radiographic bone healing patterns we would like to examine the mechanism of osseointegration. We randomly used 8 male and female house rabbit amd used diameter 5 mm height spiral shaped implants(Ostem, Korea) for animal use handled as a resorbable blast machined(RBM) surface and machined surface. 2group were formed and each group had RBM surface and machined surface implant or a simple bone cavity. After 3, 7, 14 and 28 days post surgery 2 objects were sacrificed from each group and histologic specimens were acquired. RT-PCR analysis was conducted and after H&E staining the extent of osseointegration was measured applying a histologic feature and histomorphometric analysis program. Quanitity one -4.41(Bio-Rad, USA) was used after scanning the PCR product image of the growth factors manifested in each group. According to the histomorphometric features the RBM, Machined surface group showed increased contact between bone and implant surface at 3, 7, 14 and 28 days after surgery. The BMP2 level increased in both experiment groups but remained unchanged in the contrast group. BMP4 levels stayed steady after the early post implantation period for RBM but showed decreased in the machined surface group and contrast group. The amount of contact between bone and implant surface increased with the passage of time. BMP2, BMP4 were expressed in both experimental group and contrast group. These growth factors play a role in osseointegration of implant.