• Journal of Periodontal and Implant Science
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• v.50 no.2
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• pp.106-120
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• 2020

Purpose: A new form of porous polyethylene, characterized by higher porosity and pore interconnectivity, was developed for use as a tissue-integrated implant. This study evaluated the effectiveness of porous polyethylene blocks used as an onlay bone graft in rabbit mandible in terms of tissue reaction, bone ingrowth, fibrovascularization, and graft-bone interfacial integrity. Methods: Twelve New Zealand white rabbits were randomized into 3 treatment groups according to the study period (4, 12, or 24 weeks). Cylindrical specimens measuring 5 mm in diameter and 4.5 mm in thickness were placed directly on the body of the mandible without bone bed decortication, fixed in place with a titanium screw, and covered with a collagen membrane. Histologic and histomorphometric analyses were done using hematoxylin and eosin-stained bone slices. Interfacial shear strength was tested to quantify graft-bone interfacial integrity. Results: The porous polyethylene graft was observed to integrate with the mandibular bone and exhibited tissue-bridge connections. At all postoperative time points, it was noted that the host tissues had grown deep into the pores of the porous polyethylene in the direction from the interface to the center of the graft. Both fibrovascular tissue and bone were found within the pores, but most bone ingrowth was observed at the graft-mandibular bone interface. Bone ingrowth depth and interfacial shear strength were in the range of 2.76-3.89 mm and 1.11-1.43 MPa, respectively. No significant differences among post-implantation time points were found for tissue ingrowth percentage and interfacial shear strength (P>0.05). Conclusions: Within the limits of the study, the present study revealed that the new porous polyethylene did not provoke any adverse systemic reactions. The material promoted fibrovascularization and displayed osteoconductive and osteogenic properties within and outside the contact interface. Stable interfacial integration between the graft and bone also took place.

• Journal of Periodontal and Implant Science
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• v.49 no.1
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• pp.14-24
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• 2019

Purpose: To assess the influence of using different combinations of guided bone regeneration (GBR) materials on volume changes after wound closure at peri-implant dehiscence defects. Methods: In 5 pig mandibles, standardized bone defects were created and implants were centrally placed. The defects were augmented using different combinations of GBR materials: xenogeneic granulate and collagen membrane (group 1, n=10), xenogeneic granulate and alloplastic membrane (group 2, n=10), alloplastic granulates and alloplastic membrane (group 3, n=10). The horizontal thickness was assessed using cone-beam computed tomography before and after suturing. Measurements were performed at the implant shoulder (HT0) and at 1 mm (HT1) and 2mm (HT2) below. The data were statistically analysed using the Wilcoxon signed-rank test to evaluate within-group differences. Bonferroni correction was applied when calculating statistical significance between the groups. Results: The mean horizontal thickness before suturing was $2.55{\pm}0.53mm$ (group 1), $1.94{\pm}0.56mm$ (group 2), and $2.49{\pm}0.73mm$ (group 3). Post-suturing, the values were $1.47{\pm}0.31mm$ (group 1), $1.77{\pm}0.27mm$ (group 2), and $2.00{\pm}0.48mm$ (group 3). All groups demonstrated a loss of horizontal dimension. Intragroup changes exhibited significant differences in group 1 (P<0.001) and group 3 (P<0.01). Intergroup comparisons revealed statistically significant differences of the relative changes between groups 1 and 2 (P=0.033) and groups 1 and 3 (P=0.015). Conclusions: Volume change after wound closure was minimized by using an alloplastic membrane. The stability of the augmented horizontal thickness was most ensured by using this type of membrane irrespective of the bone substitute material used for membrane support.

• Journal of Periodontal and Implant Science
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• v.24 no.2
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• pp.303-320
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• 1994

Current acceptable methods For promotin gperiodontal regeneration are base on removal of diseased soft tissue, root treatment, guided tissue regeneration, inteoduction of new graft materials and biological mediators. Platelet-derived growth factor(PDGF) is one of polypeptide growth factor. PDGF has been reported as a biological mediator which regulates activities of wound healing process including the cell proliferation, migration and metabolism. The purposes of this study is to evaluate the effects of PDGF-AA, BB on the periodontal ligament cells to use as a regeneration promoting agent of periodontal tissue. Human periodontal ligament cells were prepared from the first premolar tooth extracted for the orthodontic treatment and were cultured in DMEM/10% FBS at the $37^{\circ}C$, 5% $CO_2$ incubator. Author measured the DNA synthesis, total protein, collagen and noncollagenous protein synthesis and alkaline phosphatase activity according to the concentration of PDGF-AA and BB(0, 0.1, 1, 10, 100ng/ml). The results were as follows : The DNA synthetic activity was increased dose dependently by PDGF-AA and BB. The maximum mitogenic effect was at the 100ng/ml of PDGF-AA and 10ng/ml of PDGF-BB. The total protein, collagen and noncollagen systhesis was increased dose dependently by PDGF-AA and BB. The % of collagen was slightly decresed according to the concentration of PDGF-AA and BB. The effect of PDGF-AA and BB were not specific for collagen synthesis since it also increased noncollagenous protein synthesis. The effect of PDGF-AA and BB on alkaline phosphatase activity did not show any significant, meanwhile the alkaline phosphatase activity of 14 days group showed significnat increase. In conclusion, PDGF-AA and BB may have important roles in stimulation of DNA synthesis in human periodontal ligament cells, which means an increase in collagen-synthesizing cells, and may be useful for clinical application in periodontal regenerative procedures.

• Journal of Periodontal and Implant Science
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• v.24 no.2
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• pp.219-237
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• 1994

The ultimate goal of clinical periodontal therapy is to achieve regeneration of a healthy connective tissue reattachment. Conventional therapy including scaling, root planing, gingival curettage, gingivectomy and flap procedures of various types results primarily in repair rather than regeneration of the periodontium. In order for periodontal regeneration to occur, progenitor periodontal ligament cells must migrate to the denuded root surface, attach to it, proliferate and mature into an organized and functional fibrous attachment apparatus. Polypeptide growth factors belong to a class of potent biologic mediators which regulate cell differentiation, proliferation, migration and metabolism. Insulin-like growth factor-I (IGF- I ) of these factors appear to have an important role in periodontal wound healing and bone formation. The purpose of this study is to evaluate the effects of IGF- I on the periodontal ligament cells to use as a regeneration promoting agent of periodontal tissue. Human periodontal ligament cells were obtained from periodontal tissue explants culture of the first premolar tooth extracted for the orthodontic treatment. Cells were cultured in Dulbecco's modified Eagle medium(DMEM) with 10% fetal bovine serum. Fourth to seventh passage cells were plated in 24 well tissue culture plates and medium changed to serum-free medium prior to addition of growth factors. Cell proliferation was measured by the incorporation of $[^3H]-thymidine$ into DNA, Protein synthesis was determined by measurement of $[^3H]-proline$ incorporation into collagenase-digestible protein(CDP) and noncollagenous protein(NCP) according to the method of Peterkofsky and Diegelmann (1971), And alkaline phosphatase activity was measured as one parameter of osteoblastic differentiation. The results were as follows : The DNA synthetic activity was increased in a dose-dependent manner with IGF- I except for 0.1ng/ml concentration of IGF- I At the concentration of 10, 100ng/ml, IGF- I significantly increased the DNA synthetic activity(P<0.05) The total protein, collagen and noncollagen synthesis was increased in a dose-dependent manner with IGF- I except for 0.1ng/ml concentration of IGF- I. At the concentration of 1, 10, 100ng/ml, IGF- I significantly increased the total protein, collagen and noncollagen synthesis activity(P<0.95, P<0.001). The % of collagen was not effected according to the concentration of IGF- I. The alkaline phosphatase activity was increased in a dose-, time-dependent manner with IGF- I (10, 100ng/ml). In conclusions, the present study shows that IGF- I has a potentiality to enhance the DNA synthesis of periodontal ligament cells with including the increase of the total protein and collagen synthetic activity. The use of IGF- I to mediate biological stimulation of periodontal ligament cells shows promise for future therapeutic applications.

• Journal of Periodontal and Implant Science
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• v.47 no.5
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• pp.292-311
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• 2017

Purpose: Beyond the limited scope of non-specific polyclonal regulatory T cell (Treg)-based immunotherapy, which depends largely on serendipity, the present study explored a target Treg subset appropriate for the delivery of a novel epitope spreader Pep19 antigen as part of a sophisticated form of immunotherapy with defined antigen specificity that induces immune tolerance. Methods: Human polyclonal $CD4^+CD25^+CD127^{lo-}$ Tregs (127-Tregs) and $na\ddot{i}ve$ $CD4^+CD25^+CD45RA^+$ Tregs (45RA-Tregs) were isolated and were stimulated with target peptide 19 (Pep19)-pulsed dendritic cells in a tolerogenic milieu followed by ex vivo expansion. Low-dose interleukin-2 (IL-2) and rapamycin were added to selectively exclude the outgrowth of contaminating effector T cells (Teffs). The following parameters were investigated in the expanded antigen-specific Tregs: the distinct expression of the immunosuppressive Treg marker Foxp3, epigenetic stability (demethylation in the Treg-specific demethylated region), the suppression of Teffs, expression of the homing receptors CD62L/CCR7, and CD95L-mediated apoptosis. The expanded Tregs were adoptively transferred into an $NOD/scid/IL-2R{\gamma}^{-/-}$ mouse model of collagen-induced arthritis. Results: Epitope-spreader Pep19 targeting by 45RA-Tregs led to an outstanding in vitro suppressive T cell fate characterized by robust ex vivo expansion, the salient expression of Foxp3, high epigenetic stability, enhanced T cell suppression, modest expression of CD62L/CCR7, and higher resistance to CD95L-mediated apoptosis. After adoptive transfer, the distinct fate of these T cells demonstrated a potent in vivo immunotherapeutic capability, as indicated by the complete elimination of footpad swelling, prolonged survival, minimal histopathological changes, and preferential localization of $CD4^+CD25^+$ Tregs at the articular joints in a mechanistic and orchestrated way. Conclusions: We propose human $na\ddot{i}ve$ $CD4^+CD25^+CD45RA^+$ Tregs and the epitope spreader Pep19 as cellular and molecular targets for a novel antigen-specific Treg-based vaccination against collagen-induced arthritis.

• Journal of Periodontal and Implant Science
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• v.41 no.5
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• pp.218-226
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• 2011

Purpose: Micro-computed tomography (micro-CT) has been widely used in the evaluation of regenerated bone tissue but the reliability of micro-CT has not yet been established. This study evaluated the correlation between histomorphometric analysis and micro-CT analysis in performing new bone formation measurement. Methods: Critical-size calvarial defects were created using a 8 mm trephine bur in a total of 24 Sprague-Dawley rats, and collagen gel mixed with autogenous rat bone marrow stromal cells (BMSCs) or autogenous rat BMSCs transduced by adenovirus containing bone morphogenic protein-2 (BMP-2) genes was loaded into the defect site. In the control group, collagen gel alone was loaded into the defect. After 2 and 4 weeks, the animals were euthanized and calvaria containing defects were harvested. Micro-CT analysis and histomorphometric analysis of each sample were accomplished and the statistical evaluation about the correlation between both analyses was performed. Results: New bone formation of the BMP-2 group was greater than that of the other groups at 2 and 4 weeks in both histomorphometric analysis and micro-CT analysis (P=0.026, P=0.034). Histomorphometric analysis of representative sections showed similar results to histomorphometric analysis with a mean value of 3 sections. Measurement of new bone formation was highly correlated between histomorphometric analysis and micro-CT analysis, especially at the low lower threshold level at 2 weeks (adjusted $r^2=0.907$, P<0.001). New bone formation of the BMP-2 group analyzed by micro-CT tended to decline sharply with an increasing lower threshold level, and it was statistically significant (P<0.001). Conclusions: Both histomorphometric analysis and micro-CT analysis were valid methods for measurement of the new bone in rat calvarial defects and the ability to detect the new bone in micro-CT analysis was highly influenced by the threshold level in the BMP-2 group at early stage.

• Journal of Periodontal and Implant Science
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• v.34 no.2
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• pp.333-344
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• 2004

The enamel matrix derivative (EMD) has been recently used in the periodontal regenerative techniques. The present study was established to investigate the influence of EMD on human periodontal ligament cells using expression of mRNA of periodontal ligament specific gene (PDLs)17, PDLs22, type I collagen when EMD applied to periodontal ligament cells. Periodontal ligament cells were obtained from a healthy periodontium and cultured in Dulbecco's modified Eagle's medium (DMEM) plus 10% fetal bovine serum and ${\beta}-glycerophosphate$ with ascorbic acid. Test groups were two; One adds EMD in culture media and another added EMD and Dexamethasone (DEX) in culture media. Positive control group added DEX in culture media, and negative control group adds niether of EMD nor DEX. $Emdogain^{(R)}$ (Biora, Sweden, 30 mg/ml) was diluted by 75 ${\mu}g/ml$ concentration to culture media. For reverse transcription-polymerase chain reaction (RT-PCR), total RNA isolated on days 0, 7, 14 and 21. mRNA of PDLs17 was expressed on days 14 and 21 in EMD or DEX group, and expressed on days 7, 14 and 21 in EMD plus DEX group, the other side, expressed on days 21 in negative control group. mRNA of PDLs22 expressed on days 7, 14 and 21 in EMD group, and expressed on days 14 and 21 in DEX group, and expressed on days 7, 14 and 21 in EMD plus DEX group. Negative control group expressed on days 14 and 21. Type I collagen was expressed on all days and all groups. These results indicate that EMD promotes differentiation of periodontal ligament cells, and this is considered to offer basis that can apply EMD to periodontal tissue regeneration technique.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.703-719
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• 1995

The purpose of this study was to observe the effects of the periodontal ligament on the healing and the formation of alveolar bone in the extraction socket, when this ligament had artificially remained in the socket during the tooth removal. Twenty rats aged 4 weeks were used and devided into the control groups (10) and the experimental groups (10) in this study. The maxillary right and left first molars were extracted in both groups. In the experimental groups the periodontal ligament was remained in the extraction sockets using 0.4% ${\beta}-aminopropionitrile$, and in the control the periodontal ligament was completely removed by curettage. At 1, 3, 5, 7 and 14 days after the tooth extraction, rats in both groups were serially sacrificed. And the specimens were prepared with Hematoxylin-Eosin stain for the light microscopic evaluation. The results of this study were as follows ; 1. On 1 day, the periodontal ligament was only found in the extraction socket walls of the experimental groups, and there was not the distinguishable difference between the control and the experimental groups. 2. On 3 days, there were more collagen fibers and the appearance of higher cellular density in the experimental groups than in the control. And the cells and collagen of the periodontal ligament were so actively proliferated and synthesized that invaded into the connective tissue of the extraction sockets in the experimental groups. 3. In the experimental groups, the trabecular bone was formed on the basal and lateral bone surface on 5 days. However, there was not the new bone forming appearance in the control groups at this time. 4. On 7 days, the trabecular bone was formed in the control groups. 5. On 14 days, the extraction sockets were almost entirely filled with the bony trabeculae in both groups. But, compared to the control group, the experimental groups showed the prominent differences in the amount & the density of the new bone formed. In conclusion, it was suggested that the residual periodontal ligament tissue in the extraction socket will play a major role as the important cell source in the healing and the new bone formation of the extraction socket.

• Journal of Periodontal and Implant Science
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• v.33 no.2
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• pp.289-299
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• 2003

The autogenous free gingival graft is the most predictable procedure currently used to increase the width of　the attached gingiva in periodontics. But the major disadvantage of the procedure is to create the multiple surgical wounds at both a donor site and a recipient site. The other problem is the limited amount of available　graft material in oral cavity. Therefore, recent researches have been focused to develop the biomaterial to substitute the autogenous gingival tissue. The purpose of this study was to evaluate the histologic healing after　grafting of bilayer artificial dermis, compared to the free gingival graft. Four non-smoking subjects (mean age, 32.5 years) in systemically healthy state and good oral hygiene were selected according to their particular needs for correction of mucogingival problems as suggested by Nabers(1966). The recipient sites were prepared through the procedure for the free gingival graft and were grouped according to the graft materials: Experimental group(n=5) - bilayer artifcia1 dermis ($Terudermis^{(R)}$; Terumo Co. Japan) and Control group(n=6) - free gingival graft with autogenous palatal mucosa. Biopsies were harvested at 1,2,3 and 6 weeks postsurgery to evaluate histologically. At the third week in the experimental group and at the second week of in the control group, the grafts has been clinically stabilized on the recipient bed and the graft border has been blended into the surrounding tissue. In the experimental group after 1 week of grafting, the epithelial migration from the adjacent tissue to graft material was seen and after 3 weeks of grafting, the : nflmmation decreased, collagen layer of the artificial dermis was lost and the basement membrane of epithelium was formed. After 6 weeks of grafting, both groups demonstrated orthokeratinized epithelium and increased thickness of epithelial tissue and the rete peg formation, similar to the adjacent tissue, Histologic evaluation revealed a biologic acceptance and incorporation of the collagen layers of the graft tissue to the host tissue, without foreign body reaction. In conclusion, a bilayer artificial dermis is essentially similar to autogeneous free gingival graft in the correction of mucogingival problems, and has the advantages of decreased patient morbidity (no donor site) and availability of abundant amounts of graft material when needed.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.2
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• pp.142-149
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• 2008

The purpose of this study was to evaluate histomorphometrically a toothash - plaster of Paris mixture associated with collagen membrane ($Bio-Gide^{(R)}$), regarding new bone formation in the peri-implantitis defects in dogs. Three mandibular molars were removed from 1-year-old mongrel dogs. After 2 months of healing, 2 titanium implants with sandblasted with large grit and acid etched (SLA) surface were installed in each side of the mandible. Experimental peri-implantitis was induced with ligatures after successful osseointegration. Ligatures were removed after identification of bone defect beneath the level of 5th thread of fixture on radiographic image. The mucoperiosteal flaps were elevated and the contaminated fixtures were treated with chlorhexidine and saline. The bone defects were assigned to one of the following treatments: no guided bone regeneration (GBR) procedure (group 1), GBR with Bio-$Oss^{(R)}$ and Bio-$Gide^{(R)}$ (group 2), or GBR with toothash - plaster of Paris mixture (TPM) and Bio-$Gide^{(R)}$ (group 3). The dogs were sacrificed after 8 or 16 months. The mean percentages of new bone formation within the limits of the 5 most coronal threads were $17.83{\pm}10.69$ (8 weeks) and $20.13{\pm}13.65$ (16 weeks) in group 1, $34.25{\pm}13.32$ (8 weeks) and $36.33{\pm}14.21$ (16 weeks) in group 2, and $46.33{\pm}18.39$ (8 weeks) and $48.00{\pm}17.78$ (16 weeks) in group 3, respectively. The present study confirmed statistically considerable new bone formation within the threads in group 3 compared with group 1 at 8 and 16 weeks (P<0.05). Although, data analysis did not reveal significant differences between group 2 and 3, the latter showed better results during the period of 8 or 16 weeks. Our findings support the effectiveness of TPM as a GBR material in the treatment of peri-implantitis bone defect.