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ABSTRACT: Considerable effort has been directed towards replacing lost teeth using tissue-engineering methods such as titanium implants. A number of studies have tried to modify bioinert titanium surfaces by coating them with functionally bioactive molecules for faster and stronger osseointegration than pure titanium surfaces. Recently, peptides have been recognized as valuable scientific tools in the field of tissue-engineering. The DLTIDDSYWYRI motif of the human laminin-2 α2 chain has been previously reported to promote the attachment of various cell types; however, the in vivo effects of the DLTIDDSYWYRI motif on new bone formation have not yet been studied. To examine whether a laminin-2-derived peptide can promote osseointegration by accelerating new bone formation in vivo, we applied titanium implants coated with the DLTIDDSYWYRI motif in a rabbit tibia model. The application of the DLTIDDSYWYRI motif-treated implant to tibia wounds enhanced collagen deposition and alkaline phosphatase expression. It significantly promoted implant osseointegration compared with treatment with scrambled peptide-treated implants by increasing the bone-to-implant contact ratio and bone area. These findings support the hypothesis that the DLTIDDSYWYRI motif acts as an effective osseointegration accelerator by enhancing new bone formation.
Biomaterials 03/2013; · 7.40 Impact Factor
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ABSTRACT: Laminin-derived peptide coatings can enhance epithelial cell adhesion to implants, and the positive effect of these peptides on bone cell adhesion has been anticipated. The purpose of this study was to evaluate the improvement in bone cell attachment to and activity on titanium (Ti) scaffolds coated with a laminin-derived functional peptide, Ln2-P3 (the DLTIDDSYWYRI motif). Four Ti disc surfaces were prepared, and a human osteosarcoma (HOS) cell attachment test was performed to select two candidate surfaces for peptide coating. These two candidates were then coated with Ln2-P3 peptide, a scrambled peptide, or left uncoated to measure cell attachment to each surface, following which one surface was chosen to assess alkaline phosphatase (ALP) activity and osteogenic marker gene expression with quantitative real-time PCR. On the commercially pure Ti surface, the Ln2-P3 coating significantly increased cellular ALP activity and the expression levels of ALP and bone sialoprotein mRNA as compared with the scrambled peptide-coated and uncoated surfaces. In conclusion, although further in vivo studies are needed, the findings of this in vitro study indicate that the Ln2-P3-coated implant surface promotes bone cell adhesion, which has clinical implications for reducing the overall treatment time of dental implant therapy.
BioMed research international. 01/2013; 2013:638348.
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ABSTRACT: The microbiota that forms on implant surfaces placed in the human body can be highly resistant to antimicrobial agents and in some cases cause life-threatening infections. Consequently, to limit bacterial attachment to these surfaces and thereby minimize the risk of implant infection, the process of biofilm formation and bacterial attachment must be well-understood. The oral environment is considered to be an excellent model for research into biofilm formation and implant infection, accounting for many studies carried out in the field of dental medicine. Those studies show that the roughness, free energy, and material characteristics of the implant surface largely determine initial bacterial adhesion. This article reviews the relevant literature on these aspects of biofilm formation.
The International journal of artificial organs 10/2012; · 1.86 Impact Factor
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ABSTRACT: Objectives: The purpose of this study was to evaluate initial bacterial adhesion on several restorative materials with similar roughness. Materials and methods: Sixty cylindrical slabs were prepared from four restorative materials: zirconia (Zr), alumina-toughened zirconia (Al-Zr), type III gold alloy (Au), and cp-titanium (Ti). All the materials were polished until a mirror-like shine was achieved. The average surface roughness and topography were determined by atomic force microscopy. Contact angles were measured to calculate surface free energy by the sessile drop technique. After the formation of a salivary pellicle, S. sanguinis, S. gordonii, and S. oralis were inoculated onto the specimens and incubated for 4 h. Quantification of the adherent bacteria was performed by crystal violet staining technique and resazurin reduction assay. One-way ANOVA and Tukey's post hoc test were adopted for statistical analysis. The level of significance was 0.05.Results: The Ra values determined with atomic force microscopy for all specimens were lower than 5 nm. Surface free energy increased in the order of Al-Zr, Zr, Ti, and Au. Differences were significant between the investigated materials in both crystal violet absorbance and fluorescence intensities. Gold alloy showed the highest values for all bacterial strains (p<0.05).Conclusions: Zirconia, alumina-toughened zirconia, and titanium may be more suitable than gold alloy as an abutment material with respect to the initial bacterial adhesion and subsequent advance of peri-implantitis.
The International journal of artificial organs 10/2012; · 1.86 Impact Factor
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ABSTRACT: PURPOSE:: To compare between a bioactive and a bioinert implant with different geometries by continuous measurement of the removal torque and calculation of the angular momentum of each surfaced implant. MATERIALS AND METHODS:: Six New Zealand white rabbits were used in the study. Each rabbit received 2 implants. A bioactive fluoride-modified implant with a conical connection and microthread design was inserted into one tibia, and a bioinert anodically oxidized implant with an external connection design was inserted into the other. After 2 weeks of implant insertion, the removal torque values were continuously measured according to time. Using the time-torque curve resulting from the measurements, the maximum values were determined, and the angular momenta were calculated. RESULTS:: The anodically oxidized implant had significantly higher peak removal torque and angular momentum values than the fluoride-modified implant (P < 0.05). CONCLUSIONS:: The impact of the fluoride-modified bioactive implant on early bone response remains unclear. Considering the angular momentum of dental implants may assist in the elucidation of the effect of implant geometry on bone response.
Implant dentistry 09/2012; 21(5):427-432. · 1.51 Impact Factor
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ABSTRACT: OBJECTIVE: The aim of this study was to estimate the effects of zirconia implants and recombinant human bone morphogenetic protein-2 (rhBMP-2) gel on the acceleration of local bone formation and osseointegration in the canine mandible. MATERIALS AND METHODS: Four groups of 48 implants with identical geometry were installed in the mandibles of beagle dogs: alumina-blasted zirconia implants applied with rhBMP-2, alumina-blasted zirconia implants applied with demineralized bone matrix (DBM), alumina-blasted zirconia implants, and resorbable blast media-treated titanium (Ti) implants. For the first two groups, zirconia implants were inserted after the surgical sites were filled with rhBMP-2 or DBM gel. For the other two groups, zirconia or Ti implants were installed with no adjunctive treatment. Fluorescent bone markers were administered to monitor bone remodeling at weeks 2, 4, and 5 postimplantation. After healing periods of 3 weeks and 6 weeks, the animals were sacrificed, and fluorescent microscopy, histology, and histomorphometric analyses were performed. RESULTS: Fluorescent microscopy showed that bone formation around the zirconia implants installed with rhBMP-2 gel was the most prominent at 2 weeks postimplantation, while the Ti implants acquired bone apposition mainly at week 5. No significant differences were found in bone area among the groups (P > 0.05). The zirconia implants showed similar bone-to-implant contact to the Ti implants. There were no significant differences in bone-to-implant contact between the zirconia implants with rhBMP-2 gel and those with DBM (P > 0.05). CONCLUSIONS: The zirconia implants with alumina-blasted surfaces may achieve osseointegration in much the same manner as the well-established Ti implants. The area influenced by rhBMP-2 gel, including the alveolar crest, may cause active remodeling and early bone formation.
Clinical Oral Implants Research 08/2012; · 2.51 Impact Factor
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ABSTRACT: Fracture of the veneering material of zirconia restorations frequently occurs in clinical situations. The purpose of this in vitro study was to compare the fracture strengths of zirconia crowns veneered with various ceramic materials by various techniques.
A 1.2 mm, 360° chamfer preparation and occlusal reduction of 2 mm were performed on a first mandibular molar, and 45 model dies were fabricated in a titanium alloy by CAD/CAM system. Forty-five zirconia copings were fabricated and divided into three groups. In the first group (LT) zirconia copings were veneered with feldspathic porcelain by the layering technique. In the second group (HT) the glass ceramic was heat-pressed on the zirconia coping, and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented onto their titanium dies with Rely X™ Unicem (3M ESPE) and loaded with a universal testing machine (Instron 5583) until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc test (α=0.05). Scanning electron microscope was used to investigate the fractured interface.
Mean fracture load and standard deviation was 4263.8±1110.8 N for Group LT, 5070.8±1016.4 for Group HT and 6242.0±1759.5 N for Group ST. The values of Group ST were significantly higher than those of the other groups.
Zirconia crowns veneered with CAD/CAM generated glass ceramics by the sintering technique are superior to those veneered with feldspathic porcelain by the layering technique or veneered with glass ceramics by the heat-pressing technique in terms of fracture strength.
The journal of advanced prosthodontics 08/2012; 4(3):162-9.
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ABSTRACT: The aim of this study was to investigate whether bioactive surfaces were more favorable to bone than bioinert surfaces by evaluating bone responses around two commercial dental implants.
Bioactive fluoride-modified implants (Osseospeed) were compared with bioinert oxidized implants (TiUnite). Field emission scanning electron microscopy, energy dispersive spectroscopy, and confocal laser scanning microscopy analyzed the implant surface characteristics. Five New Zealand white rabbits were used to evaluate the bone response. Each rabbit received two implants: a fluoride-modified implant in one tibia and an oxidized implant in the other. Drilling was performed bicortically, and a gap defect was created in the upper cortexonly. Bone-to-implant contact and bone area were measured on the histological specimens 2 weeks after implant insertion.
No significant differences were found in surface roughness (P > 0.05). The gap defects were almost filled with new bone within a period of 2 weeks. The histomorphometry revealed no significant differences in bone-to-implant contact and bone area (P > 0.05).
Within the limitation of this study, the bioactive fluoride-modified surface may show no superiority to the bioinert anodized surface in early bone response.
Implant dentistry 02/2012; 21(2):124-8. · 1.51 Impact Factor
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Child s Nervous System 03/2011; 27(7):1165-8. · 1.54 Impact Factor
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ABSTRACT: One of the major keys to achieve successful osseointegration of the implant is its surface properties. The aim of this study was to investigate the bone response to dental implants with different surface characteristics using the rabbit tibia model. Tricalcium phosphate (TCP) coated, anodic oxidized and turned (control) surfaces were compared.
Seventy two implants were placed in the tibia of eighteen rabbits. Nine rabbits were sacrificed at 3 weeks of healing and the remaining nine were sacrificed at 6 weeks of healing. The bone-to-implant contact (BIC) and the bone volume density (BVD) were assessed by light microscope after 3 and 6 weeks of healing.
Statistical analysis showed that no significant differences in the BIC and BVD were observed between the different implant surfaces and the control group at 3 weeks and 6 weeks of healing. Data also suggested that the BVD of all the surfaces showed significant difference at 3 and 6 weeks.
The present study has showed that osseointegration occurred in all investigated types of surface-treated implants. In the current study all of the threads of the implants were observed to calculate BIC and BVD values (instead of choosing some of the threads from the bone cortex for example), which didn't make BIC or BVD percentage values better than in the control group, therefore the clinical relevance of these results remains to be shown.
The journal of advanced prosthodontics 12/2010; 2(4):142-7.
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ABSTRACT: The aim of this study was to investigate the effect of a macroscopic groove on bone response and implant stability during the early stages of healing using a rabbit tibia model.
Anodized titanium implants with (n=24) and without (n=24) macroscopic grooves were prepared. A total of 12 rabbits were used and each received four implants: six rabbits with implants with macroscopic grooves (test group) and six rabbits with implants without macroscopic groves (control group). Histomorphometry, resonance frequency, and removal torque value were evaluated 2 and 6 weeks post-implant-insertion.
At 2 and 6 weeks, there was no significant difference between the two groups in the percentage of bone-to-implant contact (P>0.05). At 6 weeks, the test group had significantly higher implant stability quotient values than the control group (P<0.05). At 2 and 6 weeks, implants with grooves showed a significantly greater resistance to reverse torque than control implants (P<0.05).
The groove on the oxidized titanium surface may increase both resistance to shear load and adhesion at the bone-implant interface. A geometric feature such as a macroscopic groove may facilitate osseointegration and increase implant stability in various clinical conditions. Further studies are required to confirm whether the improvement in implant stability will enhance treatment success in humans.
Clinical Oral Implants Research 12/2010; 21(12):1379-85. · 2.51 Impact Factor
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ABSTRACT: A 23-year-old female with aggressive periodontitis was treated using dental implants and LAVA system. The severely compromised teeth were extracted irrespective of initial conservative periodontal treatment. An implant-supported overdenture with 4 implants was fabricated for the maxilla and all-ceramic restorations for the mandible. Esthetic and functional goals were achieved with team approach involving periodontists and prosthodontists. This case report describes a treatment procedure for a generalized aggressive periodontitis patient with severe bone resorption.
The journal of advanced prosthodontics 09/2010; 2(3):97-101.
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ABSTRACT: The use of segmental instrumentation technique using pedicle screw has been increasingly popular in recent years owing to its biomechanical stability. Recently, intralaminar screws have been used as a potentially safer alternative to traditional fusion constructs involving fixation of C2 and the cervicothoracic junction including C7. However, to date, there have been few clinical series of C7 laminar screw fixation in the literature. Thus, the purpose of this study is to report our clinical experiences using C7 laminar screw and the early clinical outcome of this rather new fixation technique.
Thirteen patients underwent C7 intralaminar fixation to treat lesions from trauma or degenerative disease. Seventeen intralaminar screws were placed at C7. The patients were assessed both clinically and radiographically with postoperative computed tomographic scans.
There was no violation of the screw into the spinal canal during the procedure and no neurological worsening or vascular injury from screw placement. The mean clinical and radiographic follow up was about 19 months, at which time there were no cases of screw pull-out, screw fracture or non-union. Complications included two cases of dorsal breech of intralaminar screw and one case of postoperative infection.
Intralaminar screws can be potentially safe alternative technique for C7 fixation. Even though this technique cannot be used in the cases of C7 laminar fracture, large margin of safety and the ease of screw placement create a niche for this technique in the armamentarium of spine surgeons.
Journal of Korean Neurosurgical Society 08/2010; 48(2):129-33. · 0.60 Impact Factor
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ABSTRACT: A heat-treated PVA nanofibrous matrix containing silver (Ag) was prepared by electrospinning an aqueous 10 wt% PVA solution and followed by heat treatment at 150 degrees C for 10 min. The average diameter of the as-spun and heat-treated PVA nanofibers was 330 nm. The heat-treated PVA nanofibrous matrix containing Ag was irradiated with UV light to transform the Ag ions in the nanofibrous matrix into Ag nanoparticles. The in vitro cytotoxicity of the Ag ions and/or nanoparticles on normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF) cultures was examined. The PVA nanofibrous matrix containing Ag showed slightly higher level of attachment and spreading in the early stage culture (1 h) than the PVA nanofibers without Ag (control). However, compared with the PVA nanofibers without Ag, the heat-treated and UV-irradiated PVA nanofibers, containing mainly Ag ions and nanoparticles, respectively, showed reduced cell attachment and spreading. This shows that both Ag ions and Ag nanoparticles are cytotoxic to NHEK and NHEF. There was no significant difference in cytotoxicity to NHEK and NHEF between Ag ions and Ag nanoparticles. NHEF appeared to be more sensitive to Ag ions or particles than NHEK. In addition, the residual nitrate ions (NO3(-)) in the PVA nanofibers had an adverse effect on the culture of both cells.
Colloids and surfaces. B, Biointerfaces 07/2010; 78(2):334-42. · 2.60 Impact Factor
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ABSTRACT: The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function.
Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading.
All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year.
Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.
The journal of advanced prosthodontics 06/2010; 2(2):54-7.
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ABSTRACT: Many dental clinicians are concerned about immediate loading of inserted implants. However, there have been few clinical studies surveying the success rates of immediate loading, based on Korean implant systems.
The aim of this study was to evaluate the outcome of immediate functional loading of the implant (SinusQuick™ EB, Neobiotech Co., Seoul, Korea) in partially edentulous maxilla or mandible.
Total 15 implants were placed. Within 2 weeks after implant insertion, provisional implant-supported fixed partial dentures were delivered to the patients. Quantitatively, marginal bone loss was measured at the time of immediate loading, after 3-months of continued loading and at the last follow-up. The mean follow-up period was 4.8 months.
Mean marginal bone loss from implant surgery to early loading, 3-months follow-up and last follow-up was 0.03 ± 0.07 mm, 0.16 ± 0.17 mm and 0.29 ± 0.19 mm. No implant failed up to 6 months after insertion, resulting in a 100% survival rate.
Immediate loading exhibited high success rate in partial edentulism for up to 6 months. Well-controlled long term clinical studies with large sample size are necessary to confirm this finding.
The journal of advanced prosthodontics 11/2009; 1(3):136-9.
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ABSTRACT: Silk fibroin (SF) nanofibers were prepared by electrospinning and treated with plasma in the presence of oxygen or methane gas to modify their surface characteristics. The surface characteristics of the SF nanofibers after plasma treatment were examined using contact angle measurements and XPS analysis. The hydrophilicity of the electrospun SF nanofibers decreased slightly by the CH(4) plasma treatment. On the other hand, the hydrophilicity of the SF nanofibers increased greatly by an O(2) plasma treatment. The O(2)-treated SF nanofibers showed higher cellular activities for both normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF) than the untreated ones.
International journal of biological macromolecules 01/2009; 44(3):222-8. · 2.37 Impact Factor
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ABSTRACT: To fabricate a biomimetic nanostructured bicomponent scaffolds, two types of chitin/silk fibroin (SF) nanofibrous scaffolds (blend scaffolds and hybrid scaffolds) were prepared by electrospinning or simultaneous electrospinning of chitin/SF solutions. The chitin/SF bicomponent scaffolds were after-treated with water vapor, and their nanofibrous structures were almost maintained. From the cytocompatibility and cell behavior on the chitin/SF blend or hybrid nanofibrous scaffolds, the hybrid matrix with 25% chitin and 75% SF as well as the chitin/SF blend nanofibers could be a potential candidate for tissue engineering scaffolds.
International Journal of Biological Macromolecules 06/2008; 42(4):324-34. · 2.45 Impact Factor
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ABSTRACT: The aim of this study was to investigate the early bone response to the titanium dental implants with different surface characteristics using the rabbit tibia model. Calcium metaphosphate coated, anodic oxidized, hydroxyapatite particle-blasted, and turned (control) surfaces were compared. Surface topography was evaluated by field emission scanning electron microscope and optical interferometer. Eighteen rabbits received 72 implants in the tibia. Resonance frequency was analyzed every week for 6 weeks. Removal torque values were measured 2 and 6 weeks after placement. The implant-bone interfaces were directly observed by light microscope and bone-to-implant contact ratios were measured 2 and 6 weeks after insertion. All the surface-modified implants showed superior initial bone responses to the control. No significant differences were found among the surface-modified groups. Data suggest that various surface modification methods can provide favorable bone responses for early functioning and healing of dental implants.
Journal of Biomedical Materials Research Part B Applied Biomaterials 05/2008; 87(2):303-11. · 2.15 Impact Factor
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ABSTRACT: Electrospinning of collagen (COL)/silk fibroin (SF) blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol was investigated for fabrication of a biocompatible and biomimetic nanostructured scaffold for tissue engineering. The morphology of the electrospun COL/SF blend nanofibers was observed by scanning electron microscopy. The average diameters of COL/SF blend fibers ranged from 320 to 360 nm, irrespective of SF content in the blends. Both COL and SF components in the as-spun COL/SF blend matrices were stabilized by glutaraldehyde and water vapor, respectively, under the saturated glutaraldehyde aqueous solution at 25 degrees C. The glutaraldehyde vapor chemically stabilized the COL component via cross-linking, whereas the water vapor physically stabilized the SF component via crystallization to the beta-sheet structure. These structural changes of after-treated COL/SF blend matrices were examined using ATR-IR and CP/MAS (13)C NMR spectroscopy. To assay the cytocompatibility and cellular behavior of the COL/SF blend nanofibrous scaffolds, cell attachment and the spreading of normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF) seeded on the scaffolds were studied. In addition, both morphological changes and cellular responses of COL/SF blend nanofibrous matrices were also compared with COL/SF hybrid nanofibrous matrices. Generally similar levels of cell attachment and spreading of NHEF were shown in the COL/SF blend nanofibrous matrix compared with those of the pure COL and pure SF matrices; the cellular responses of NHEK were, however, markedly decreased in the COL/SF blend nanofibrous matrix as compared to the pure matrices. In contrast, cell attachment and spreading of NHEK on the COL/SF hybrid nanofibrous matrix were significantly higher than that of the COL/SF blend nanofibrous matrix. Our results indicate that a COL/SF hybrid nanofibrous matrix may be a better candidate than a COL/SF blend nanofibrous matrix for biomedical applications such as wound dressing and scaffolds for tissue engineering.
Biomacromolecules 05/2008; 9(4):1106-16. · 5.48 Impact Factor
