• Journal of Periodontal and Implant Science
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• v.29 no.2
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• pp.355-373
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• 1999

Many researches have been reported that collagen as cellular stroma, matrix of grafting materials, mediator of agents for the purpose of promoting healing process invivo, but the responses in vivo were seen various. The goal of this experiment is to assess the effect of collagen on bony healing, through histological evaluation of implanted collagen on the calvarial defect in rats. 2-month-old Sprague-Dawley, 24 rats were used and 12 rats assigned to each group of control and test. Defect of 5mm in diameter was made on the calvarial bone with trephine bur. Following thorough saline rinse, defect of control group was left in empty and that of experimental group was filled with fibrillar collagen($COLLATAPE^{(R)}$, COLLA-TEC. INC. U.S.A.) soaked in saline. 3 rats in each group were sacrificed at 3, 7, 14, 21 days after operation respectively, and the tissue blocks were prepared for light microscope with H-E for evaluation of overall healing, with TRAP(tartrate resistant acid phosphatase) for evaluation of osteoclastic activity and with immunohistochemical staining for macrophages. The results were as follows : 1. In the control group, inflammatory responses were disappeared at day 14, but, in the experimental group inflammatory infiltrates were reduced at day 21. Thus, the experimental group showed more severe soft tissue inflammation than control group. 2. Both control and experimental group showed slight appositional growth at day 7 and gradual bony growth to 21th day. But, complete bony healing of the defect was not shown. There was no significant difference in bony healing between control and experimental group 3. Specific response of macrophages for implanted collagen was observed at day 14 in the experimental group. In conclusion, although fibrillar collagen caused inflammation of soft tissue during initial healing period, inflammatory responses by fibrillar collagen didn't inhibit bony regeneration and implanted collagen was biodegradaded by macrophages. Thus, we expect that fibrillar collagen can be used for useful mediator of graft materials or growth factors.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.249-262
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• 1997

The present study investigates the effects of calcium sulfate graft on the periodontal healing in intrabony periodontal defects of dogs. Following the general anesthesia with 30mg/kg pentobarbital injected intravenously, the first premolar was extracted and full-thickness periodontal flap was elevated from the second premolar to the fourth premolar. The portion of premolars coronal to the alveolar crest was removed and mesial and distal roots were separated. Exposed root canals were sealed with Caviton and covered completely with flaps sutured. Following the healing period of 12 weeks, the surgical sited were uncovered and $4{\times}4mm$ intrabony defects were surgically created. Those defects with calcium sulfate graft following the root planing was designated as the test sites and those with flap surgery-only were designated as control sites. The animals were sacrificed after 8 weeks and the healing was histologically analyzed. The results were as follows. 1. No foreign body reaction or inflammation were observed in either groups. Calcium sulfate was completely resorbed in the test sites. 2. New cementum was observed coronal to the notch in both groups. Connective tissue fibers were oriented parallel to the root surface in the controls. Connective tissues were formed in large amount in the sites. 3. Test sites showed marked amount of new bone formation while the control sites showed minimal bone gain. 4. Root resorption was observed in coronal portions of th control Sites. The results suggest that calcium sulfate is a biocompatible graft material with a potential for new bone and cementum formation.

• Journal of Periodontal and Implant Science
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• v.29 no.4
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• pp.873-893
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• 1999

The ultimate goal of periodontal therapy is the regeneration of periodontal tissue and repair of function. For more than a decade there have been many efforts to develop materials and bioactive molecule(such as growth factor and differentiation factors) to promote periodontal wound healing. Among the bioactive molecules, bone morphogenetic protein(BMP) was studied for periodontal wound healing. Since Urist demonstrated that demineralized bone matrix could induce the formation of cartilage and bone in ectopic site, many studies on BMP have been reported. Among those BMPs, it was reported that rhBMP-2 enhanced the healing of bone defects in animal studies and clinical studies. However, its efficacy in periodontal regeneration, especially 1-wall intrabony defects is still unknown. The purpose of this study was to examine the effect of rhBMP-2/ACS on the epithelial migration, gingival connective tissue adhesion, cementum formation, alveolar bone regeneration in intrabony defects of dogs. Four millimeter deep and four millimeter wide 1-wall defects were surgically created in the mesial aspects of the 3rd incisors. The test group received rhBMP-2/ACS with a flap procedure and the control underwent buffer/ACS with a flap procedure. Histologic analysis after 8 weeks of healing revealed the following results: 1. The length of epithelial growth(the distance from alveolar crest to the apical end of JE) was $0.9{\pm}1.5mm$ in the control group and $1.2{\pm}1.4mm$ in the test group. There was no statistically significant difference between the two groups. 2. The length of connective tissue adhesion was $2.4{\pm}1.3mm$ in the control group and $1.2{\pm}1.1mm$ in the test group. The control group showed significantly enhanced adhesion(P<0.05). 3. The length of new cementum was $0.9{\pm}1.0mm$ in the control group and $1.7{\pm}0.8mm$ in the test group. The test group showed significantly enhanced cementum regeneration(P<0.05). 4. The length of new bone height was $1.9{\pm}0.6mm$ in the control group and $2.4{\pm}0.9mm$ in the test group. There was no statistically significant difference between the two groups. 5. The new bone area was $4.7{\pm}1.7mm^2$ in the control group and $8.0{\pm}2.0mm^2$ in the test group. The test group showed significantly enhanced bone formed area(P<0.05). 6. The new bone density was $73.0{\pm}8.6%$ in the control group and $66.6{\pm}15.3%$ in the test group. There was no statistically significant difference between the two groups. These results suggest that the use of rhBMP-2 in 1-wall intrabony defects has significant effect on new cementum and new bone formation area, but doesn't have any significant effect on the prevention of junctional epithelium migration and new bone formation height.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.19 no.1
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• pp.15-24
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• 1997

The principle of guided tissue regeneration (GTR), as applied to bone healing, is based on the prevention of connective tissue from entering the bony defect during the healing phase. This allows the slower bone producing cells to migrate into and reproduce bone within the defect. GTR has demonstrated a level of success in regenerating bone defect. Several types of membrane barrier have been utilized to apply this principle in bone regeneration. The purpose of this study was to evaluate whether improved bone regeneration can be achieved with different membrane barriers ($Gore-Tex^{TM}$membrane, $COLLACOTE^{(R)}$). In the 10 NewZealand white rabbits, full-thickness bone defects on three sites of each rabbit calvaria were made. Experimental group 1 was covered with $COLLACOTE^{(R)}$, and group 2 was covered with $Gore-Tex^{TM}$membrane. Macroscopic, microscopic examinations were made serially on 1, 2, 3, 6, 12 weeks after operation. The results were as follows : 1. Macroscopically, both of experimental group 1, 2 were filled with bone-like mass but the defects of experimental group 1 disclosed markedly thinner than the original bone. 2. Microscopically, the defect of experimental group 1, 2 was filled with bony trabeculae without infection and adverse reaction. But multinucleated giant cell infiltration around $COLLACOTE^{(R)}$ was seen till 6th week. 3. Resorption of $COLLACOTE^{(R)}$ started from 3rd week and it was completely resorped on the 12th week.

• Journal of Periodontal and Implant Science
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• v.40 no.1
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• pp.3-10
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• 2010

Purpose: Periodontal regenerative therapies for defects created by severe periodontitis are mainly focused on bone regeneration. Although cementum regeneration needs to be better understood, it is believed to play an important role in periodontal regeneration. The first step toward a full understanding of cementum regeneration is to compare repaired cementum to pristine cementum. This study, which used histological techniques, was designed to focus on cementum regeneration and to compare pristine cementum to repaired cementum after surgical procedures with 8 and 24 week healing periods in a canine model. Methods: Buccal and lingual mucoperiosteal flaps of 10 beagle dogs were surgically reflected to create critical-sized defects. Intrabony one-wall defects, of which dimension is 4 mm width and 5 mm depth, were made at the distal aspect of mandibular second premolars and the mesial aspect of mandibular fourth premolars in the right and left jaw quadrants. Animals were sacrificed after 8 and 24 weeks post-surgery for histological specimen preparation and histometric analysis. Results: The repaired cementum was composed mostly of acellular cementum and cellular mixed fiber cementum and was thicker in the apical area than in the coronal area. The acellular cementum of the supracrestal area appeared to be amorphous. The newly formed cellular cementum was partially detached from the underlying circumpulpal dentin, which implied a weak attachment between new cementum and dentin, and this split was observed to a lesser extent in the 24 week group than in the 8 week group. The vertical height of the repaired cementum was greater in the 24 week group than in the 8 week group. Conclusions: Within the limitations of this study, we can conclude that repaired cementum after root planing was mainly acellular cementum and cementum tissue that matured to a shape similar to pristine cementum as the healing progressed from 8 to 24 weeks.

• Oral Biology Research
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• v.42 no.4
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• pp.198-207
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• 2018

Guided tissue regeneration (GBR) has been used to promote new bone formation in alveolar bone reconstruction at defective bone sites following tooth loss. Bone grafts used in GBR can be categorized into autogenous, xenogenous, and synthetic bones, and human allografts depending on the origin. The purpose of this study was to compare the rates of bone regeneration using two different bone grafts in the cranial defects of rabbits. Ten New Zealand rabbits were used in this study. Four defects were created in each surgical site. Each defect was filled as follows: with nothing, using a 50% xenograft and 50% human freeze-dried bone allograft (FDBA) depending on the volume rate, human FDBA alone, and xenograft alone. After 4 to 8 weeks of healing, histological and histomorphometric analyses were carried out. At 4 weeks, new bone formation occurred as follows: 18.3% in the control group, 6.5% in group I, 8.8% in group II, and 4.2% in group III. At 8 weeks, the new bone formation was 14.9% in the control group, 36.7% in group I, 39.2% in group II, and 16.8% in group III. The results of this study suggest that the higher the proportion of human FDBA in GBR, the greater was the amount of clinically useful new bone generated. The results confirm the need for adequate healing period to ensure successful GBR with bone grafting.

• Journal of Periodontal and Implant Science
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• v.27 no.1
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• pp.165-177
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• 1997

The purpose of this study was to perform on the biological activity of Magnolia and Zizyphi fructus extract mixtures on the wound healing of defected rat calvaria. For the determination of the mixture ratio of two extracts for oral administration, preliminary experiments were performed with the mixture combination of 2000 and $3000{\mu}g/ml$ of Magnolia extract, and also 20, 30, 200, 300, 2000 and $3000{\mu}g/ml$ of Zizyphi fructus extract, respectively and divided into 6 groups. The combination of extracts mixture were tested on the enhancing effect of cellular activity. The effect of the extracts mixture on the cellular activity was evaluated using MTT method and measured on the results with optical density by ELISA reader. The ability to tissue regeneration of the extracts mixture was performed by measuring new bone and new connective tissue regeneration on the 5mm defected rat calvaria for 1, 2 and 3 weeks after oral administration of 2 different dosages groups : 10:1(0.1g/kg) and 10:1(0.5g/kg). It was employed the same dosages of unsaponifiable fraction of Zea Mays L as positive controls. Each group of rat was sacrificed and en bloc section for histological examination. The effect on the cellular activity of each mixture ratio showed significantly higher in $2000{\mu}g/ml$ of Magnolia extract and $200{\mu}g/ml$ of Zizyphi fructus extract group to compare with other groups. These preliminary results showed that appropriate mixture ratio of two extracts was 10:1 of Magnolia and Zizyphi fructus extract. Histological examination on the activity of tissue regeneration of each group showed that 2weeks and 3weeks specimens of 0.5g/kg of 10:1 extract mixture of Magnolia and Ziziphi fructus administrated rat calvaria revealed significantly more osteoid and new bone formation of defected calvaria with unification of defected area than the specimens of any other negative and positive controls. Even though the specimen administrated the same dosages of unsaponifiable fraction of Zea Mays L, positive controls, showed the trend that they promote significantly the repair of calvarial defect, their bone reparative activities were less inductive than the same dosages of Magnolia and Ziziphi fructus extract mixture. These results implicated that the mixture of Magnolia and Zizyphi fructus extracts should be highly effective on the wound healing of bony defected site and might have potential possibilities as an useful drug to promote periodontal tissue regeneration.

• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.119-126
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• 2015

Among the various human growth factors, epidermal growth factor (hEGF, consisting of 53 amino acids) has various effects on cell regeneration, stimulation of proliferation, migration of keratinocytes, formation of granulation tissues, and stimulation of fibroblast motility, which are important for wound healing. Owing to their multiple activities, EGFs are used as pharmaceutical and cosmetic agents. However, their low productivity, limited target specificity, and short half-life inhibit their application as therapeutic agents. To overcome these obstacles, we fused the collagen-binding domain (CBD) of Vibrio mimicus metalloprotease to EGF protein. About 18 or 12 amino acids (aa) (of the 33 total amino acids), which were essential for collagen-binding activity, were combined with the N- and C-termini of EGF. We constructed, expressed, and purified EGF (53 aa)-CBD (18 aa), EGF (53 aa)-CBD (12 aa), CBD (18 aa)-EGF (53 aa), and CBD (12 aa)-EGF (53 aa). These purified recombinant proteins increased the numbers of cells in treated specimens compared with non-treated specimens and control hEGF samples. The collagen-binding activities were also evaluated. Furthermore, CBD-hybridized hEGF induced phosphorylation of the EGF receptor. These results suggested that these fusion proteins could be applicable as small therapeutic agents in wound tissue healing.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.161-172
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• 2002

The present study evaluated the effects of guided tissue regeneration using xenograft material(deproteinated bovine bone powder), with and without biodegradable membrane in beagle dogs. Contralateral fenestration defects (6 ${\times}$ 4mm) were created 4 mm apical to the buccal alveolar crest of maxillary premolar teeth in 5 beagle dogs. Deproteinated bovine bone powders were implanted into fenestration defect and one randomly covered biodegradable membrane (experimental group). Biodegradable membrane was used to provide GTR. Tissue blocks including defects with soft tissues which were harvested following four & eight weeks healing interval, prepared for histo-phathologic analysis. The results of this study were as follows. 1. In control group, at 4 weeks after surgery, new bony trabecular contacted with interstitial tissue and osteocytes like cell were arranged in new bony trabecule. Bony lamellation was not observed. 2. In control gruop, at 8 weeks after surgery, scar-like interstitial tissue was filled defect and bony trabecule form lamellation. New bony trabecular was contacted with interstitial tissue but defect was not filled yet. 3. In experimental group, at 4 weeks after surgery, new bony trabecular partially recovered around damaged bone. But new bony trabecular was observed as irregularity and lower density. 4. In experimental group, at 8 weeks after surgery, lamella bone trabecular developed around bone cavity and damaged tissue was replaced with dense interstitial tissue. In conclusion, new bone formation regenerated more in experimental than control groups and there was seen observe more regular bony trabecular in experimental than control groups at 4 weeks after surgery. In control group, at 8 weeks after surgery, the defects was filled with scar-like interstitial tissue but, in experimental group, the defects was connected with new bone. Therefore xenograft material had osteoconduction but could not fill the defects. We thought that the effective regeneration of periodontal tissue, could be achieved using GTR with biodegradable membrane.

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.205-221
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• 1998

The present study invetigates the effects of root planing only(control group), DFDBA alone(test group 1) and combined use of DFDB and Dura mater(test group 2) in dehiscence defects in dogs. The results of 8weeks post-surgery by histological comparison between the three groups are as follows. 1. The contol group showed minimum regeneration of new cementum and new bone with limited migration of epitheilal cells, and healed by connective tissue attachment. 2. The test group 1 showed minimum regeneration of new cementum and new bone with limited migration of epitheilal cells, and healed by connective tissue attachment. 3. The test group 2 showed significant amount of the new cementum and new bone. 4. Both control and test groups healed without any observable root resorption and ankylosis. The above the results suggest that the use of resorbable Dura mater only does not improve the regeneration of new bone and periodontal ligament due to difficulties of space making, but the combined use with DFDB may be more effective.