• 대한치과재료학회지
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• 제45권4호
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• pp.243-256
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• 2018

본 연구에서는 생체활성 타이타늄 차폐막의 제조에 필요한 기초적인 자료를 얻기 위해서 타이타늄 박판의 양극산화처리와 석회화 순환처리의 조건 및 이들 표면처리가 표면특성과 생체활성도에 미치는 영향에 대하여 조사하였다. $30{\times}20{\times}0.08mm$의 타이타늄 판을 준비한 다음 $HNO_3:HF:H_2O$를 12 : 7 : 81 로 혼합한 용액에서 10 초 동안 산세처리 후 사용하였다. 타이타늄 차폐막의 비표면적을 증가시키기 위해서 나노튜브 $TiO_2$층을 형성한 후, 하이드록시아파타이트의 석출에 따른 생체활성도를 개선하기 위해서 석회화 순환처리를 하였다. 표면처리된 표면특성을 평가하기 위해서, 부식에 대한 저항성시험, 젖음성 검사, 유사체액 침적시험을 실시하였다. 양극산화처리로 형성된 나노튜브들은 상대적으로 큰 직경의 튜브들과 작은 직경의 튜브들로 구성되어 있었으며, 내부는 비어있고 외벽은 서로 결합되어 있는 구조를 보였다. 연속적으로 시행된 석회화 순환처리로 나노튜브층에 하이드록시아파타이트 석출물이 침투되어 결합이 일어났으며, 순환처리 회수가 증가함에 따라서 HAp 의 석출량이 비례적으로 증가하는 경향을 보였다. 결론적으로, 타이타늄 차폐막의 표면에 나노튜브 $TiO_2$ 층을 형성한 후 석회화 순환처리를 하여서 HAp 의 석출을 유도하는 것은 생체활성도 개선에 크게 기여할 수 있다는 것을 확인하였다.

• BMB Reports
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• 제45권5호
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• pp.281-286
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• 2012

Osteoclasts are multinucleated cells that are formed by the fusion of pre-fusion osteoclasts (pOCs). The fusion of pOCs is known to be important for osteoclastic bone resorption. Here, we examined the effect of IFN-${\gamma}$ on the fusion of pOCs. IFN-${\gamma}$ greatly increased the fusion of pOCs in a dose-dependent manner. Furthermore, IFN-${\gamma}$ induced pOC fusion even in hydroxyapatite-coated plates used as a substitute for bone. The resorption area of pOCs stimulated with IFN-${\gamma}$ was significantly higher than that of the control cells. IFN-${\gamma}$ induced the expression of dendritic cell-specific transmembrane protein (DC-STAMP), which is responsible for the fusion of pOCs. IFN-${\gamma}$ enhanced DC-STAMP expression in a dose-dependent manner. The mRNA expression of c-Fos and nuclear factor of activated T cells (NFAT) c1 was enhanced in the pOCs treated with IFN-${\gamma}$. Taken together, these results provide a new insight into the novel role of IFN-${\gamma}$ on the fusion of pOCs.

• 한국재료학회지
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• 제8권9호
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• pp.865-870
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• 1998

생체내에서 매식되는 타이타늄의 표면에 골의 형성과 성장을 촉진시키기 위해 칼슘이온과 인산이온을 함유하는 용액에서 타이타늄의 표면처리를 행하였다. 표면처리방법으로는 pH 5.8, 7.0, 8.0의 인산칼슘 완충용액에 10분간 침적시킨 후 유사체액에 30일간 침적시켰다. 침적시킨 후의 타이타늄 표면에 형성된 피막의 특성을 주사전자현미경, X-ray 회절장치, Fourier 변환강도계등으로 확인하고 유사체액에만 침적한 시편의 표면특성과 비교하였다. 실험결과 인산완충용액에서의 침적에 의해 타니타늄 표면에 인산칼슘 형성이 촉진됨을 알 수 있었다. 형성된 층은 입자형의 미세구조를 지닌 하이드록시아파타이트나 $\beta$-TCP의 인산칼슘 층으로 확인되었다. 형성된 층의두께는 pH 8.0, 7.0 그리고 pH 5.8의 인산완충액에서의 침적 순으로 증가하였고, 그 밀도는 pH 7.0, pH8.0그리고 pH5.8의 인산완충액에서의 침적 순으로 증가하였다.

• 대한치과보철학회지
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• 제34권4호
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• pp.722-745
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• 1996

The purpose of this study is to investigate the effect of constant direct current electrical stimulation in healing the bone defects and surrounding tissues of the endo-oseous(TPS-IMZ) implants. Implants were inserted in the femur of adult dogs. Then a constrant direct current of approximately $10{\mu}A$ was applied. Artificial bone defects were prepared on one side of the implant site. Experimental groups were divided into 4 : control group : bone defect without treatment group I : bone defect filled with hydroxyapatite powders group II : bone defect, in which a negative and positive electrodes were inserted 5mm apart from both sides of the implant group III : bone defect, in which negative current was directly connected to the IMZ implant and a positive electrode was placed 10mm apart from the implant The animals were sacrificed in the 1st, 2nd, 4th and 8th week after implantation for the light microscopic examination. The results obtained were as follows : 1. In electrically stimulated experimental groups, new bone formation and osseointegration around implants were accelerated. 2. Group III showed the greatest activity in new bone formation. Osteoconductivity around HA particles was observed in group 1. 3. The defect area of the control group was healed by forming new bone, which grew from the underlying cancellous bone. The defect areas of the electrically stimulated experimental groups were healed by newly formed bone, which grew upward from the cancellous bone and downward from the periosteum. 4. 8 weeks after implantation, all the groups showed good osseointegration between the surrounding bone and implants.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제37권4호
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• pp.278-286
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• 2011

Introduction: This study examined the predictability of new bone formation in the pneumatized maxillary sinus using only fibrin-rich blocks with concentrated growth factors as an alternative to bone grafts. Materials and Methods: Maxillary sinus augmentation was performed in thirty-three patients with a deficient alveolar bone height (mean 3.9 mm). All patients were treated consecutively with sinus membrane elevation via the lateral window approach and panoramic radiograms and cone-beam computed tomograms were taken to evaluate the remaining bone height and the new bone formation in the maxillary sinus, before and after surgery. Four biopsy specimens were taken at the time of implant consolidation (after an average of five months healing) and were stained by H & E and Trichrome staining. Results: None of the patients had postoperative complications during implant consolidation. After an average of 5 months since sinus augmentation, newly formed bone was observed in all cases by a radiographic evaluation. In 4 biopsy samples, newly formed bone was observed along the floor of the replaced bony window. The osteoblast lining and well distinguished Osteocytes in the lacunas were observed in the newly formed bone. Of the 74 implants (4 different surfaced implants - resorbable blast media-surfaced (RBM), Hydroxyapatite (HA) coated, acid-etched, sintered porous-surfaced implant) placed, one RBM implant failed. The success rate was 98.6% after a mean of 15 months. Discussion: These results suggest that maxillary sinus augmentation using fibrin rich block with concentrated growth factors is a successful and predictable technique.

• International Journal of Oral Biology
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• 제30권3호
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• pp.99-103
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• 2005

Bone morphogenetic proteins (BMPs), members of a large group of TGF-beta family, are important molecular regulators of morphogenesis of numerous tissues and organs, including bones and teeth. Most BMPs are capable of inducing bone formation in vivo and therefore are of considerable clinical interest for regenerating mineralized tissues. Recently, we have developed a method to culture cells from human cementum (human cementum-derived cells, HCDCs). HCDCs, when attached to synthetic hydroxyapatite/tricalcium phosphate (HA/TCP) ceramic and transplanted into immunodeficient mice, formed histologically identifiable cementum-like tissue. Since it is unclear to what extent BMPs are involved in cementogenesis, the aim of this study was to establish which BMPs are expressed by cementogenic HCDCs and whether the expression of BMPs is related to the degree of cellular differentiation in vitro. HCDCs were maintained in growth medium (DMEM/F12 supplemented with 10% FBS) until confluent (proliferation stage). Upon reaching confluence, cells were incubated in the differentiation medium (DMEM/F12 medium containing 10% FBS and 50 mg/ml ascorbic acid) for 14 days (differentiation stage). Next, HCDCs were incubated in mineralization medium (DMEM/F12, 50 mg/ml ascorbic acid, 2.5 mg/ml of ITS (insulin-transferrinselenium), 5 mM beta-glycerophosphate and $10^{-8}M$ dexamethasone) for another 14 days (mineralization stage). At the end of each differentiation stage, total RNA was isolated and evaluated for BMPs (2 through 8) expression by employing real time RT-PCR. HCDCs expressed most of BMPs examined except BMP-7 and BMP-8. Furthermore, on average, the highest levels of BMPs were expressed at the earlier differentiation stage, prior to the initiation of mineralization in vitro. These results indicate that several BMPs are expressed during cementoblastic differentiation and suggest that BMPs may be involved in the homeostasis of human cementum.

• 한국표면공학회지
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• 제54권5호
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• pp.238-247
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• 2021

PEO (plasma electrolytic oxidation) was applied to modify the surface of AZ31 magnesium alloy in this study. The mixed solution of sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) was used as the electrolyte, and 0 - 0.05 g/L of Ca-GP (Glycerol Phosphate Calcium salt) was added in the electrolyte as an additive. PEO treatment was conducted at a current density of 30mA/cm² for 5 minutes using a DC power supply. The surface properties were identified by SEM, XRD and surface roughness analyses, and the corrosion resistance was evaluated by potentiodynamic polarization and immersion tests. In addition, the biocompatibility was evaluated by immersion test in SBF solution. As the concentration of Ca-GP was increased, the surface morphology was denser and more uniform, and the amount of Ca and the thickness of oxide layer increased. Only Mg peak was observed in XRD analysis due to very thin oxide layer. The corrosion resistance of PEO-treated samples increased with the concentration of Ca-GP in comparision with the untreated sample. In particular, the highest corrosion resistance was identified at the group of 0.04g Ca-GP through potentiodynamic polarization and immersion tests in saline solution (0.9 wt.%NaCl). During the immersion in saline solution, pH rapidly increased at the beginning of immersion period due to rapid corrosion, and then increase rate of pH decreased. However, the pH value in the SBF temporarily increased from 7.4 to 8.5 during the day, then decreased due to the inhibition of corrosion with HA(hydroxyapatite) formation.

• Journal of Periodontal and Implant Science
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• 제49권1호
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• pp.25-38
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• 2019

Purpose: This study evaluated differences in bone healing and remodeling among 3 implants with different surfaces: sandblasting and large-grit acid etching (SLA; IS-III $Active^{(R)}$), SLA with hydroxyapatite nanocoating (IS-III $Bioactive^{(R)}$), and SLA stored in sodium chloride solution ($SLActive^{(R)}$). Methods: The mandibular second, third, and fourth premolars of 9 dogs were extracted. After 4 weeks, 9 dogs with edentulous alveolar ridges underwent surgical placement of 3 implants bilaterally and were allowed to heal for 2, 4, or 12 weeks. Histologic and histomorphometric analyses were performed on 54 stained slides based on the following parameters: vertical marginal bone loss at the buccal and lingual aspects of the implant (b-MBL and l-MBL, respectively), mineralized bone-to-implant contact (mBIC), osteoid-to-implant contact (OIC), total bone-to-implant contact (tBIC), mineralized bone area fraction occupied (mBAFO), osteoid area fraction occupied (OAFO), and total bone area fraction occupied (tBAFO) in the threads of the region of interest. Two-way analysis of variance (3 types of implant $surface{\times}3$ healing time periods) and additional analyses for simple effects were performed. Results: Statistically significant differences were observed across the implant surfaces for OIC, mBIC, tBIC, OAFO, and tBAFO. Statistically significant differences were observed over time for l-MBL, mBIC, tBIC, mBAFO, and tBAFO. In addition, an interaction effect between the implant surface and the healing time period was observed for mBIC, tBIC, and mBAFO. Conclusions: Our results suggest that implant surface wettability facilitates bone healing dynamics, which could be attributed to the improvement of early osseointegration. In addition, osteoblasts might become more activated with the use of HA-coated surface implants than with hydrophobic surface implants in the remodeling phase.

• Journal of Periodontal and Implant Science
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• 제52권2호
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• pp.116-126
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• 2022

Purpose: This study evaluated the efficacy of treating periodontitis using subgingival nano-hydroxyapatite powder with an air abrasion device (NHAPA) combined with scaling and root planing (SRP). Methods: A total of 28 patients with stage III periodontitis (grade B) were included in this study, although 1 was lost during follow-up and 3 used antibiotics. The patients were divided into a test group and a control group. All patients first received whole-mouth SRP using hand instruments, and a split-mouth approach was used for the second treatment. In the test group, the teeth were treated with NHAPA for 15 seconds at 70% power per pocket. Subgingival plaque samples were obtained from the 2 deepest pockets at the test and control sites before treatment (baseline) and 3 months after treatment. The full-mouth plaque index (PI), gingival index (GI), papillary bleeding index (PBI), bleeding on probing (BOP), probing depth (PD) and clinical attachment level (CAL) were recorded at baseline and at 1- and 3-month post-treatment. Real-time polymerase chain reaction was used to determine the colonisation of Treponema denticola (Td), Porphyromonas gingivalis (Pg), and Aggregatibacter actinomycetemcomitans in the subgingival plaque. Results: From baseline to the first month, the test group showed significantly larger changes in BOP and CAL (43.705%±27.495% and 1.160±0.747 mm, respectively) than the control group (36.311%±27.599% and 0.947±0.635 mm, respectively). Periodontal parameters had improved in both groups at 3 months. The reductions of PI, GI, BOP, PD, and CAL in the test group at 3 months were greater and statistically significant. The total bacterial count and Td and Pg species had decreased significantly by the third month in both groups (P<0.05). Conclusions: Applying NHAPA in addition to SRP improves clinical periodontal parameters more than SRP alone. Subgingival NHAPA may encourage clot adhesion to tooth surfaces by increasing surface wettability.

• 한국치위생학회지
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• 제22권5호
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• pp.461-468
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• 2022

Objectives: To investigate the effect of several elder-friendly foods on oral health and suggest guidelines for proper food intake. Methods: Six elderly-friendly foods (liquid type) and two control groups (mineral water and mixed coffee) were selected for this study. The pH of the food was measured using a calibrated pH meter, and the titratable acidity was determined using 1 M NaOH until 7.0 (TA 7.0). The screening method suggested by the International Organization for Standards was performed using an undersaturated hydroxyapatite solution to determine the difference between the initial and final pH of the screening solution (△pH). In addition, the sugar content was measured and expressed as Brix (%). Results: All the elder-friendly foods tested in this study showed a neutral pH (6.68-7.35), similar to mineral water (pH 7.84). The range of TA 7.0 values was 0.00-0.54 ㎖. The changes in pH determined using the screening solution confirmed that the largest change in pH was found in Careon (△pH 1.14±0.02), which has no erosive potential. Nevertheless, all elder-friendly foods had higher sugar content than the negative control group. Conclusions: Low tooth erosive potential was found in elder-friendly foods, but these foods showed high sugar content.