• The Journal of Korean Academy of Prosthodontics
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• v.39 no.6
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• pp.659-681
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• 2001

Platelet-rich plasma(PRP) has been known to increase the rate and degree of bone formation by virtue of growth factors in concentrated platelets. Although its great healing effect on bone defect or pre-implantation site preparation in conjunction with bone substitute has been reported, the effect associated with implant is unknown. The purpose of this study was to investigate the effect of PRP on rapid osseointegration of endosseous dental implants in the rabbit tibiae. Twenty two adult female New Zealand white rabbits, weighing approximately 2.7-3.3kg, were used for this study. Twelve of the 22 animals were used for histomorphometric analysis and ten of the 22 were for removal torque test. Each animal received two implants in each tibia (two treated with PRP and two as control) and was given fluorochrome intramuscularly. For histomorphometric analysis, rabbits were divided into four groups according to the healing period. At 1 week, 2 weeks, 4 weeks and 8 weeks postoperatively, each three animals were sacrificed serially and the amount and rate of bone formation around dental implant were examined on the undecalcified sections under fluorescent microscope, polarized microscope and light microscope connected to a personal computer equipped with image analysis system. For removal torque test, rabbits were divided into two groups and removal torque tests were performed at 4 weeks, 10 weeks after implant placement. In total, 88 screw shaped, commercially pure titanium implants (Neoplant, Neobiotech, Seoul, Korea) were used in this study. Labeling pattern reflected differences of two groups in bone formation rate at each period. Histomorphometrically, PRP group showed significantly higher bone volume within threads compared to control group at 2 weeks ($70.30{\pm}4.96%$ vs. $50.68{\pm}6.33%$; P < .01) and 4 weeks ($82.59{\pm}5.94%$ vs. $72.94{\pm}4.57%$; P < .05 ). PRP group at 1, 2 and 4 weeks revealed similar degree of bone volume formation comparable to control group at 2, 4 and 8 weeks, respectively. On the other hand, while PRP group showed higher bone-implant contact ($47.37{\pm}8.09%$) than control group ($33.16{\pm}13.47%$) at 2 weeks, there were no significant differences between PRP group and control group for any experimental period. Removal torque values also showed no significant differences between PRP group and control group at any experimental period (P > .05). These findings imply that PRP could induce rapid, more bone formation around implant during early healing period and get faster secondary stability for reducing healing period, though it has not induced bone maturation enough to resist functional loading.

• 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 Korean Foot and Ankle Society
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• v.14 no.1
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• pp.58-65
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• 2010

Purpose: This study was performed to evaluate the clinical outcomes of operative treatment using porous hydroxyapatite for intraarticular calcaneal fracture of joint depression type. Materials and Methods: Twenty patients with intraarticular calcaneal fracture were followed up for more than 1 year. The period to union was calculated to evaluate the osteoconductivity of porous hydroxyapatite used as bone graft substitute. The measurement of Bohler angle, Gissane angle and the degree of articular surface depression was performed through preoperative and postoperative radiographs. The clinical evaluation was performed according to hindfoot score of the American Orthopaedic Foot and Ankle Society (AOFAS) and scale of the Creighton-Nebraska health foundation (CNHF). Results: Bohler angle and Gissane angle had improved significantly from preoperative average $10.4^{\circ}$, $117.8^{\circ}$ to average $22.6^{\circ}$, $113.5^{\circ}$ immediate postoperatively, and had maintained to average $21.2^{\circ}$ and $114.4^{\circ}$ at the last follow-up. The degree of articular surface depression had improved significantly from preoperative average 4.8 mm to 1.5 mm at the last follow-up. All cases achieved bone union, and the interval to union was average 12.8 weeks. AOFAS score was average 85.2 points at last follow-up. There were 7 excellent, 10 good, and 3 fair results according to the CNHF scale. Therefore, 17 cases (85%) achieved satisfactory results. Conclusion: Plate fixation using porous hydroxyapatite seems to be one of effective treatment methods for intraarticular calcaneal fracture of joint depression type, because of supporting the reduction of subtalar articulation by augmenting bony defect and facilitating bone formation. Further evaluation about long-term radiological changes and histological analysis on hydroxyapatite implantation site should be required.

• Journal of Chest Surgery
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• v.41 no.2
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• pp.160-169
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• 2008

Bakcground: To treat anastomosis site stenosis and occlusion of the artificial vessels used in vascular surgery, tissue-engineered artificial vessels using autologous cells have been constructed. We developed artificial vessels using a polymer scaffold and autologous bone marrow cells and performed an in vivo evaluation. Material and Method: We manufactured a vascular scaffold using biodegradable PLCL (poly lactide-co-${\varepsilon}$-caprolactone) and PGA (poly glycolic acid) fibers. Then we seeded autologous bone marrow cells onto the scaffold. After implantation of the artificial vessel into the abdominal aorta, we performed an angiography 3 weeks after surgery. After the dogs were euthanized we retrieved the artificial vessels and performed histological analysis. Result: Among the six dogs, 2 dogs died of massive bleeding due to a crack in the vascular scaffold 10 days after the operation. The remaining four dogs lived for 3 weeks after the operation. In these dogs. the angiography revealed no stenosis or occlusion at 3 weeks after the operation. Gross examination revealed small thrombi on the inner surface of the vessels and the histological analysis showed three layers of vessel structure similar to the native vessel. Immunohistochemical analysis demonstrated regeneration of the endothelial and smooth muscle cell layers. Conclusion: A tissue engineered vascular graft was manufactured using a polymer scaffold and autologous bone marrow cells that had a structure similar to that of the native artery. Further research is needed to determine how to accommodate the aortic pressure.

• Journal of Periodontal and Implant Science
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• v.35 no.3
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• pp.563-575
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• 2005

The aim of present study is to evaluate the influence of adjacent tooth to the microbiology of clinically healthy implant. Control group included patients who had clinically healthy implant and tooth with healthy $periodontium(PD{\leq}3mm)$, test group was composed of patients who had clinically healthy implant and tooth with periodontal pocket(PD>3mm). The criteria of clinically health implant are no pain or discomfort, the restorative suprastructure provide satisfactory fit and function, and the tissue around the fixtures were firm and probing with standard periodontal probe with a rounded tip 0.5mm in diameter resulted in penetration of no more than 5mm when using a force of 0.5N at any location. 38 patients, partially edentulous subjects with endosseous root-form implants were selected. All subjects were medically healthy and had not taken systemic antibiotics and professional plaque control 3 months before sampling. Number of control group is 25(mean age $52{\pm}13$, 26 teeth, 34 implants) and test group is 13(mean age $60{\pm}13$, 13 teeth, 17 implants). All teeth and implants of each patient were examined probing depth(PD), bleeding on probing(BOP), and plaque index(PI), and samples of subgingival plaque were obtained at each site with sterile curet or fine paper points, then the plaque transferred to PBS. Obtained samples were examined for the presence of P. gingivalis, T. forsythensis, and T. denticola by the polymerase chain reaction(PCR). The relationship among clinical parameters and the colonizations by the 3 bacterial species from natural teeth and implants region were analyzed by student t-test. The results of this study were as follows: 1. PD was different in teeth between 2 groups(p<0.05), but the other parameters were not. 2. Statistically significant difference was not found in clinical parameters of implants between 2 groups. 3. All bacterial prevalences of teeth were higher in test group than in control group, and prevalence of T. forsythensis had statistically significant difference between 2 groups(p<0.05). 4. Prevalences of P. gingivalis and T. forsythensis are higher in test group than control group, and that of T. denticola is higher in control group than in test group. But there were no statistically significant differences between 2 groups. In conclusion, there is no statistically significant difference in prevalence of implant microbiology between 2 groups. But if the number of samples increased, it will be possible to find out statistical significance in prevalence of P. gingivalis. It seems that pocket of adjacent tooth influences prevalence of P. gingivalis. These results mean that improvement of the periodontal condition before implantation is very important.

• The Journal of the Korean dental association
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• v.47 no.11
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• pp.758-768
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• 2009

Purpose : Schulte introduced immediate implant cases in 1970s, since then many patients have been treated by immediate implants. The aim of this study was to evaluate the cumulative survival rate of immediate implant and to analyze various factors associated with survival of immediate implant in a 8-year period retrospectively. Materials and methods : From May, 2000 to October, 2007, 77 implants were placed in 63 patients immediately after tooth extraction at Department of Periodontology, Yonsei University Hospital. The implant survival rate was analyzed using a life-table analysis. After delivery of prosthesis, along 1 year of observation period, all implants were evaluated clinically and radiographically. Results : Among 77 implants, 59 were placed in maxilla and 18 in mandible. The most common site of the implantation was Mx anterior (65%). The overall survival rate was 94.8% over a mean follow-up period of $44.2{\pm}21$ months and the 8-year cumulative survival rate was 94.6%. Failure occurred in 4 implants, all of which were due to early failures. None of the following factors were significantly associated with the survival of immediate implants: advanced surgical technique including bone graft and guided bone regeneration, the types of implants, causes of tooth loss, and types of prosthesis. Conclusion : On the basis of 8-year life time analysis, immediate implant placement can be considered a safe and predictable treatment mordality.

• Journal of Korean Foot and Ankle Society
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• v.25 no.4
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• pp.149-156
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• 2021

Purpose: Given the lack of definite evidence-based guidelines in clinical practice, there may be a wide variation in treatment protocols for osteochondral lesions of the talus (OLT). Based on the Korean Foot and Ankle Society (KFAS) member survey, this study aimed to report the current trends in the management of OLT. Materials and Methods: A web-based questionnaire containing 30 questions was sent to all KFAS members in September 2021. The questions were mainly related to clinical experience and preferences in diagnosis, conservative, and surgical treatments for patients with OLT. Answers with a prevalence of ≥50% of respondents were considered a tendency. Results: Sixty-two (11.3%) of the 550 surgeons queried responded to the survey. The responses to 9 (30.0%) of the total of 30 questions established a tendency. Answers exhibiting a tendency were as follows; additional diagnostic tools except for plain radiograph (magnetic resonance imaging), most common conservative treatment method (oral medication, rest), most important radiological factor in decision making for surgical treatment and method (size of the lesion, ankle instability, loose bodies), most important patient factors in decision making for surgical treatment and method (age, activity or occupation), infrequently requiring posterior arthroscopy (less than 3%), most common revision surgery for failed bone marrow stimulation procedure (osteochondral autograft transplantation [OAT]), not requiring additional procedure for donor site in OAT, the main reason for unsatisfactory result after OAT (persistent pain without radiological abnormality), no generalization of autologous chondrocyte implantation or chondrogenesis using stem cells. Conclusion: This study presents updated information on current trends in the management of OLT in Korea. Both consensus and variations in the approach to patients with OLT were revealed through this survey. Since recent biologic efforts to regenerate cartilage have been unsuccessful, further studies to identify clinical evidence would be needed.

• Journal of Chest Surgery
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• v.43 no.1
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• pp.11-19
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• 2010

Background: The commercially used vascular xenografts have some problems such as calcification, fibrosis and tissue degeneration that are associated with inflammatory and immunologic reactions. We compared two methods of xenograft preservation (fresh cryopreservation versus acellularized cryopreservation) of goat aorta. Material and Method: Aortic valved xenografts were harvested from adult pigs, and these were preserved using fresh cryopreservation (FC group, n=4) or acellularized crypreservation (AC group, n=4). These xenografts were implanted into adult goats. There were 2 short-term survivors (less than 100 days) and 2 long-term survivors in each group. These xenografts were explanted and they underwent microscopic examination. Result: The goats survived 31, 40, 107 and 411 days in the FC group and the other goats survived 5, 40, 363 and 636 days in the AC group. All the short-term survivors in each group expired because of rupture at the proximal anastomosis site. Marked neutrophil infiltration was observed in the FC group FC and lymphocytes were observed in the AC group. There were no differences in the occurrence of calcification, fibrosis and thrombosis among the groups. Conclusion: Some goats survived more than 100 days after the xenograft implantation irrespective of the methods of preservation. Because severe tissue degeneration developed in both groups, we think these methods are not appropriate for xenograft preservation of aorta. It was worth a preliminary trial for improving the preservation method or to modify the processing of xenografts.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.1
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• pp.59-72
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• 2000

In this study, the rate of bone formation and the pattern of bone to implant contact surface around HA coated implant and pure Ti implant inserted into the irradiated tibia of rabbit were compared. Sixteen mongrel mature male rabbits were used as experimental animal. Each rabbit received 15 Gy of irradiation. Four weeks after irradiation, two holes were prepared on the tibia of each rabbit for placement of HA coated type and pure Ti type implants. Prior to implant placement, one group received steroid irrigation and the control group was similarly irrigated with normal saline. This was immediately followed by placement of the two different types of implants. Postoperatively, tetracycline was injected intramuscularly for 3 days. For fluorescent labelling, 3 days of intramuscular alizarine red injection was given. 2 weeks before sacrifice, followed by intramuscular calcein green on the last 3 days before specimen collection. Each rabbit was sacrificed on the second, fourth, sixth and eighth week after the implantation. The specimens were observed by the light microscope and the fluorescent microscope. The results were as follows; 1. All implants inserted into the irradiated tibia of rabbit were free from clinical mobility and no signs of bony resorption were noted around the site of implant placement. 2. Under the light microscope, new bone formation proceeded faster around implants that received steroid irrigation compared to the control group irrigated with saline. Bone to implant contact surface was greater in the steroid irrigated group than the saline irrigated group. Therefore, better initial stabilization was observed in the group pretreated with steroid irrigation. 3. Under the light microscope. HA coated implants showed broader bone to implant contact surface than pure Ti implants, and HA coated implants had better bone healing pattern than pure Ti implants. 4. In the steroid pretreated group, acceleration of bone formation was demonstrated by fluorescent microscopy around the 2, 4 weeks group and the 6 weeks HA coated implant group. The difference in the rate of bone formation proved to be statistically significant(P<0.05). Faster bone formation was noted in the saline irrigated group in the 6 weeks pure Ti implants and 8 weeks group. The difference was not statistically significant(P<0.05). 5. For the rabbits that were sacrificed on the second and fourth week after the implant placements, the rates of bone formation around HA coated implants proceeded faster than those around pure Ti implants under the fluorescent microscopy. For the rabbits that were sacrificed on the sixth week after the implant placements, the rates of bone formation around pure Ti implants proceeded faster than those around HA coated implants under the fluorescent microscopy. But this result did not show statistical significance (P<0.05) For the rabbits that were sacrificed on the eighth week after the implant placements, the rates of bone formation around HA coated implants proceeded faster than those around pure Ti implants under the fluorescent microscopy. This result was statistically significant (P<0.05).

• Radiation Oncology Journal
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• v.19 no.3
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• pp.230-236
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• 2001

Purpose : To evaluate treatment results in terms of local control, complications and survival after reirraidiation in recurrent cervical cancer following definite radiation therapy. Material and methods : From November 1987 through March 1998, eighteen patients with recurrent cervical cancer following definite radiation therapy were subsequently treated with reirradiation at Keimyung University Dongsan Medical Center. In regard to the initial FIGO stage, one patient was stage la, five were stage IIa, three were IIb, two were IIb and two were IVa. The age range was 37 to 79 years old with median age of 57. The time interval from initial definite radiation therapy to recurrence ranged from 6 to 122 months with a median of 58 months. The recurrent sites were the uterine cervix in seven patients, vagina in ten and pelvic lymph node in one. Reirradiation was peformed with external radiation and intracavitary radiation in twelve patients, external radiation and implantation in four and external radiation alone in two. The range of external radiation dose was $2,100\~5,400\;cGy$ and the range of the total radiation dose was $3,780\~8,550\;cGy$. The follow-up periods ranged from 8 to 20 months with median of 25 following reirradiation. Results : Fourteen of eighteen patients $(78\%)$ had local control just after reirradiation. The two year disease free survival (2YDFS) rate was $53.6\%$. There were statistically significant differences in the 2YDFS according to both recurrent site (2YDFS $28.5\%$ in uterine cervix, $71.4\%$ in vagina, (p=0.03)) and the total dose (2YDFS $71.8\%$ in >6,000 cGy , $25\%$ in $\leq6,000$ cGy, p=0.007). Seven of ten patients who were followed for more than 20 months remain alive and disease free (7/18, $39\%$). Patients treated with external radiation and intracavitary radiation had a higher rate of 2YDFS. Seven patients including 4 patients with no local control experienced local failure in the uterus or vagina and two patients died with distant metastasis. Complications included rectal bleeding in 3 patients, bowel obstruction treated with surgery in two, hematuria in one, radiation cystitis in two, soft tissue swelling in two and vaginal necrosis spontaneously healed in one. There was no statistical difference in complications according to the total dose or the time to recurrence from initial radiation. Conclusion : In patients with recurrence following definite radiation therapy in the uterine cervical cancer, reirradiation may be effective but requires an effort to reduce radiation induced severe complications.