• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.6
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• pp.461-468
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• 2009

Purpose: Platelet derived growth factor(PDGF)-BB and bone morphogenetic protein(BMP)-2 are well-known representative growth factors. The purposes of this study were to investigate the effect of rhPDGFBB and rhBMP-2 on osseointegration of titanium implants at periimplant bone defects grafted with hydroxyapatite and to evaluate the feasibility of imaging bone structures around screw-type titanium implant with micro-CT. Materials and Methods: The first molar and all premolars in the mandible region of four beagle dogs were extracted. Following a healing period of 4 months, three $8{\times}8{\times}6mm$-sized bony defects were formed and screw-type titanium implants were placed with hydroxyapatite(HA) block and growth factors; Control group, PDGF group and BMP group. Two months post-implantation, the mandible was harvested. Bone volume(BV), bone-to-implant contact(BIC) and bone mineral density(BMD) were analyzed with micro-CT and histology. Results: According to micro-CT analysis, BV and BMD measures of PDGF and BMP group were significantly higher than control group(BV; PDGF group: $p{\fallingdotseq}0.011$, BMP group: $p{\fallingdotseq}0.006$/BMD; PDGF group: $p{\fallingdotseq}0.020$, BMP group: $p{\fallingdotseq}0.011$) and BIC measures of BMP group were significantly higher than PDGF group($p{\fallingdotseq}0.015$). In histologic evaluation, BIC measures of BMP group was significantly higher than PDGF group($p{\fallingdotseq}0.048$). The values of BV in histologic sections were higher than in micro-CT images and the values of BIC in micro-CT images were higher than in histologic sections. Conclusion: The findings of this experimental study indicates that the use of rhPDGF-BB and rhBMP-2 can increase new bone formation in a large bony defect around titanium implant, and rhBMP-2 is more effective than rhPDGF-BB. Micro-CT can be considered useful for assessment as a rapid and nondestructive method for 3-dimensional measurement of bone healing around implants. Further study is necessary, however, to remove metal artifacts around titanium implant and to standardize the method.

• The Journal of Advanced Prosthodontics
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• v.8 no.5
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• pp.363-371
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• 2016

PURPOSE. On maxillofacial tumor patients, oral implant placement prior to postoperative radiotherapy can shorten the period of prosthetic reconstruction. There is still lack of research on effects of post-implant radiotherapy such as healing process or loading time, which is important for prosthodontic treatment planning. Therefore, this study evaluated the effects of post-implant local irradiation on the osseointegration of implants during different healing stages. MATERIALS AND METHODS. Custom-made implants were placed bilaterally on maxillary posterior edentulous area 4 weeks after extraction of the maxillary first molars in Forty-eight Sprague-Dawley rats. Experimental group (exp.) received radiation after implant surgery and the other group (control) didn't. Each group was divided into three sub-groups according to the healing time (2, 4, and 8 week) from implant placement. The exp. group 1, 2 received 15-Gy radiation 1 day after implant placement (immediate irradiation). The exp. group 3 received 15-Gy radiation 4 weeks after implant placement (delayed irradiation). RESULTS. The bone mineral density (BMD) was significantly lower in the immediate irradiation groups. BMD was similar in the delayed irradiation group and the control group. The irradiated groups exhibited a lower bone-to-implant contact ratio, although the difference was not statistically significant. The irradiated groups also exhibited a significantly lower bone volume and higher empty lacuna count than the control groups. No implant failure due to local irradiation was found in this study. CONCLUSION. Within the limits of this study, the timing of local irradiation critically influences the bone healing mechanism, which is related to loading time of prostheses.

• Biomaterials and Biomechanics in Bioengineering
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• v.3 no.2
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• pp.85-104
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• 2016

Stability and loosening of implanted femoral stems in Total Hip Replacement have been well established as barriers to the primary concerns of osseointegration and long term implant survival. In-vitro experiments and finite element modeling have for years been used as a primary tool to assess the bone stem interface with variable methodologies leading to a wide range of micromotion, interference fit and stress shielding values in the literature. The current study aims to provide a comprehensive review of currently utilized methodologies for in-vitro mechanical testing as well as finite element modeling of both micromotion and interference of implanted femoral stems. A total of 12 studies detailed in 33 articles were selected for inclusion. Experimental values of micromotion ranged from 12 to $182{\mu}m$ while finite element analysis reported a wider range from 2.74 to $1,277{\mu}m$. Only two studies were found that modeled bone/implant contact with consideration for interference fit. In studies evaluating stem micromotion in THA, the reference surface at the bone/stem interface should be well defined. Additionally, the amount of penetration considered should be disclosed and associated with bone density and roughness.

• Journal of Periodontal and Implant Science
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• v.53 no.3
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• pp.218-232
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• 2023

Purpose: This study evaluated the efficacy of a tube-shaped poly(ε) caprolactone - β tricalcium phosphate (PCL-TCP) scaffold with the incorporation of human umbilical cord-derived mesenchymal stem cells (hUCMSCs) and platelet-rich plasma (PRP) for bone regeneration in the procedure of single-stage sinus augmentation and dental implantation in minipigs. Methods: Implants were placed in the bilateral sides of the maxillary sinuses of 5 minipigs and allocated to a PCL-TCP+hUCMSCs+PRP group (n=5), a PCL-TCP+PRP group (n=5), and a PCL-TCP-only group (n=6). After 12 weeks, bone regeneration was evaluated with soft X-rays, micro-computed tomography, fluorescence microscopy, and histomorphometric analysis. Results: Four implants failed (2 each in the PCL-TCP+hUCMSCs+PRP and PCLTCP+hUCMSC groups). An analysis of the grayscale levels and bone-implant contact ratio showed significantly higher mean values in the PCL-TCP+hUCMSCs+PRP than in the PCL-TCP group (P=0.045 and P=0.016, respectively). In fluoromicroscopic images, new bone formation around the outer surfaces of the scaffolds was observed in the PCLTCP+hUCMSCs+PRP group, suggesting a tenting effect of the specially designed scaffolds. Bone regeneration at the scaffold-implant interfaces was observed in all 3 groups. Conclusions: Using a tube-shaped, honeycombed PCL-TCP scaffold with hUCMSCs and PRP may serve to enhance bone formation and dental implants' osseointegration in the procedure of simultaneous sinus lifting and dental implantation.

• Journal of Periodontal and Implant Science
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• v.48 no.3
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• pp.182-192
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• 2018

Purpose: The purpose of the present study was to validate an experimental model for assessing tissue integration of titanium and zirconia implants with and without buccal dehiscence defects. Methods: In 3 dogs, 5 implants were randomly placed on both sides of the mandibles: 1) Z1: a zirconia implant (modified surface) within the bony housing, 2) Z2: a zirconia implant (standard surface) within the bony housing, 3) T: a titanium implant within the bony housing, 4) Z1_D: a Z1 implant placed with a buccal bone dehiscence defect (3 mm), and 5) T_D: a titanium implant placed with a buccal bone dehiscence defect (3 mm). The healing times were 2 weeks (one side of the mandible) and 6 weeks (the opposite side). Results: The dimensions of the peri-implant soft tissue varied depending on the implant and the healing time. The level of the mucosal margin was located more apically at 6 weeks than at 2 weeks in all groups, except group T. The presence of a buccal dehiscence defect did not result in a decrease in the overall soft tissue dimensions between 2 and 6 weeks ($4.80{\pm}1.31$ and 4.3 mm in group Z1_D, and $4.47{\pm}1.06$ and $4.5{\pm}1.37mm$ in group T_D, respectively). The bone-to-implant contact (BIC) values were highest in group Z1 at both time points ($34.15%{\pm}21.23%$ at 2 weeks, $84.08%{\pm}1.33%$ at 6 weeks). The buccal dehiscence defects in groups Z1_D and T_D showed no further bone loss at 6 weeks compared to 2 weeks. Conclusions: The modified surface of Z1 demonstrated higher BIC values than the surface of Z2. There were minimal differences in the mucosal margin between 2 and 6 weeks in the presence of a dehiscence defect. The present model can serve as a useful tool for studying peri-implant dehiscence defects at the hard and soft tissue levels.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.2
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• pp.232-247
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• 2005

Purpose. The purposes of this investigation were to discover the possibility of clinical application in the areas of dental implants and bone grafts by investigating the bone formation histologically around specimen which was depending on the intensity of magnetic field of neodymium magnet inside of the specimens. Material and method. 1. Measurement of magnetic intensity - placed the magnet inside of the specimen, and measured the intensity of magnetic field around the 1st thread and 3rd thread of specimen 20 times by using a Gaussmeter(Kanetec Co., Japan). 2. Surgical Procedure - Male rabbit was anesthetised by constant amount of Ketamine (0.25ml/kg) and Rompun (0.25ml/kg). After incising the flat part of tibia, and planted the specimens of titanium implant, control group was stitched without magnet, while experimental groups were placed a magnedisc 500(Aichi Steel Co., Japan) or magnedisc 800(Aichi Steel Co., Japan) into it, fixed by pattern resin and stitched. 3. Management after the surgery - In order to prevent it from the infection of bacteria and for antiinflammation, Gentamycin and Ketopro were injected during 1 week from operation day, and dressed with potadine. 4. Preparation of histomorphometric analysis - At 2, 4 and 8 weeks after the surgery, the animals were sacrificed by excessed Ketamine, and then, specimens were obtained including the operated part and some parts of tibia, and fixed it to 10% of PBS buffer solution. After embedding specimens in Technovit 1200 and B.P solution, made a H-E stain. Samples width was 75$\mu$m . In histological findings through the optical microscope and using Kappa image base program(Olympus Co. Japan), the bone contact ratio and bone area ratio of each parts of specimens were measured and analyzed. 5. Statistical analysis - Statistical analysis was accomplished with Mann Whitney U-test. Results and conclusion. 1. In histomorphometric findings, increased new bone formation was shown in both control & experimental groups through the experiment performed for 2, 4 & 8 weeks. After 4 weeks, more osteoblasts and osteoclasts with significant bone remodeling were shown in experimental groups. 2. In histomorphometric analysis, the bone contact ratios were 38.5% for experimental group 1, 29.5% for experimental group 2 and 11.9% for control group. Experimental groups were higher than control group(p<0.05) (Fig. 6, Table IV). The bone area ratios were 60.9% for experimental group 2, 46.4% for experimental group 1 and 36.0% for control group. There was no significantly statistical difference between experimental groups and control group(p<0.05) (Fig. 8, Table VII) 3. In comparision of the bone contact ratios at each measurement sites according to magnetic intensity, experimental group 2(5.6mT) was higher than control group at the 1st thread (p<0.05) and experimental group 1 (1.8mT) was higher than control group at the 3rd thread(p<0.05) (Fig. 7, Table V, VI). 4. In comparision of the bone area ratios at each measurement sites according to magnetic intensity, experimental group 2(5.6mT) was higher than control group and experimental group 1 (4.0mT) at the 1st thread(p<0.1) and experimental group 2(4.4mT) was higher than experimental group 1 (1.8mT) at the 3rd thread(p<0.1) (Fig. 9, Table IX, X). Experiment group 2 was largest, followed by experiment group l and control group at the 3rd thread of implant. There was a significant difference at the 1st thread of control group & experiment group 2, and at 1st thread & 3rd thread of experiment group 1 & 2, and not at control group experiment group 1.(p<0.1)

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.4
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• pp.291-299
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• 2005

Objectives : It is well known that cigarette smoking is harzardous to the osseointegration of dental implant, due to the impaired wound healing accompanied by reduced alveolar bone density. The aim of this study is to evaluate the influence of cigarette smoke on the implant osseointegration by the time factor consideration. Materials and methods : Twenty-four male Spraque-Dawley rats (8 weeks, weighting 200 to 250g) were used in this study. In the experimental group, 13 rats were exposed to cigarette smoke, 8 minutes per day during 6 weeks, and 12 rats in the control group were not exposed at any time. RBM (Resorbed blasting media) surfaced implant (diameter 3.3mm, length 5.0mm, AVANA Co., Korea) was placed in the right femur of each rat. Each implant with surrounding bone was prepared with microtome (cutting band 0.2mm$^{(R)}$, EXAKT Co., Germany) after 1 day, 2, 4, 8 and 12 weeks and stained with toluidine blue (1%). Another clinical investigation of each implant was also done at each evaluation time. Results : Clinical investigation around implant fixture showed that there were no significant differences between the control and experimental group. Microscopic observation around implant fixture showed that there were significant differences between the control and experimental group at the initial stage after implant fixture installation. Experimental group showed a decreased bone to implant contact within 4 weeks compared to control group, but showed similar characteristics after 4 weeks. Conclusion : Smoking inhalation effect on the dental implant showed the impaired wound healing by vasoconstriction and decreased intramedullary blood flow at initial stage of osseointegration. This experimental results can be clinically useful to the implant surgery of smoking patients.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.498-504
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• 2014

PURPOSE. Dental implant has gained clinical success over last decade with the major drawback related to osseointegration as properties of metal (Titanium) are different from human bone. Currently implant procedures include endosseous type of dental implants with nanoscale surface characteristics. The objective of this review article is to summarize the role of nanotopography on titanium dental implant surfaces in order to improve osseointegration and various techniques that can generate nanoscale topographic features to titanium implants. MATERIALS AND METHODS. A systematic electronic search of English language peer reviewed dental literature was performed for articles published between December 1987 to January 2012. Search was conducted in Medline, PubMed and Google scholar supplemented by hand searching of selected journals. 101 articles were assigned to full text analysis. Articles were selected according to inclusion and exclusion criterion. All articles were screened according to inclusion standard. 39 articles were included in the analysis. RESULTS. Out of 39 studies, seven studies demonstrated that bone implant contact increases with increase in surface roughness. Five studies showed comparative evaluation of techniques producing microtopography and nanotopography. Eight studies concluded that osteoblasts preferably adhere to nano structure as compared to smooth surface. Six studies illustrated that nanotopography modify implant surface and their properties. Thirteen studies described techniques to produce nano roughness. CONCLUSION. Modification of dental osseous implants at nanoscale level produced by various techniques can alter biological responses that may improve osseointegration and dental implant procedures.

• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.673-682
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• 2006

Recent study shows that implant design has a great impact on initial stability in bone. The ITI $TE^{(R)}$ implant, designed originally for immediate placement has a tapered/ cylindrical form which fits the anatomical shape of the natural alvelous or tooth root. The increased diameter at the collar region coupled with more threads lead to more bone contact and enhanced stability. The aim of this retrospective study is to evaluate the clinical use and the efficacy of recently introduced ITI TE implant with a new macro-design. The following results are compiled from 139 patients who received ITl TE implant surgery at the periodontal department. of Yonsei University Hospital between July 2002 and September 2005. 1. 139 patients received 173 ITl $TE^{(R)}$ implants in their maxilla and mandible (Mx 82, Mn 91). Posterior area accounted for 84% of the whole implant surgery, 2. In the distribution of bone quality, type III(41,0%) was the most, followed by type IV(41,0%) and type II (27.7%). As for the bone quantity, type B(43.9%) was the most, followed by type C(42.2%), type D(12.2%) and type A(1.7%). 3. 125 implants(83.9%) were treated by single crown, which accounted for the majority. 4, The total implant survival rate was 100% after a mean follow-up period of 21.2 months. This preliminary data with ITl $TE^{(R)}$ implant showed excellent survival rate although the majority of implants evaluated in this study were placed in the posterior region of the jaw and compromised sites.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.594-605
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• 2006

Statement of problem: Modification of titanium implant surface has potential to ensure clinically favorable performance that several surface modification technologies have been introduced. Among the methods. anodizing method and sol-gel hydroxyapatite coating method have gained much interest due to its roughness and chemical composition of the coating layer, but more of its biocompatibility result is required. Purpose : The purpose of this study was to compare bone-implant interface shear strength of four different surface treated implants as time elapsed. Resonance frequency analysis(RFA) and removal torque measurement methods were employed to measure implant stability at one week and six week after implantation. Material and method: A total of 80 screw-shaped implant [20 machined, 20 resorbable media blasted(RBM), 20 anodized, and 20 anodized+hydroxyapatite sol-gel coated] were prepared, and one of each group was implanted in the tibia of a New Zealand white rabbit that total 20 of them were used. In order to test the implant stability and implant-tissue interface contact changing in the bone bed, each 10 rabbit were sacrificed 1 week and 6 week later while resonance frequency and removal torque were measured. One-way analysis of variance and the Tukey test were used for statistical analysis. Results : The results were as follows. 1. There was no statistically significant difference of implant stability quotients(ISQ) value in RFA between individual groups after 1 week of implantation and 6 weeks(p>0.05). But, there was statistically significant increase of ISQ value in 6 weeks group compared to 1 week group(p<0.05). 2. There was no statistically significant difference in removal torque analysis between individual groups after 1 week of implantation and 6 weeks(p>0.05). but there was statistically significant increase in all 4 groups after 6 weeks compared to 1 week later(p<0.05). 3. There was no statistically significant difference in removal torque analysis between anodized group and HA coating after anodic oxidation 6 weeks later(p>0.05), but significant difference was appeared in both groups compared to RBM group and smooth-machined group(p<0.05). Conclusions : It can be suggested that changes in surface characteristics affect bone reactions. Anodized and anodized+hydroxyapatite sol-gel coating showed significantly improved bone tissue response to implants, but further study on the effect of hydroxyapatite dissolution is needed.