Biomedical subjects

Chong-Kwan Kim

Publications and source records attributed to Chong-Kwan Kim.

At least 19 recordsLinked to original sources

PubMed2006

The effect of a fibrin-fibronectin/beta-tricalcium phosphate/recombinant human bone morphogenetic protein-2 system on bone formation in rat calvarial defects.

In spite of good prospects for bone morphogenetic proteins (BMP) applications, an ideal carrier system for BMPs has not yet been identified. The purpose of this study was to evaluate the osteogenic effect of a fibrin-fibronectin sealing system (FFSS) combined with beta-tricalcium phosphate (beta-TCP) as a carrier system for recombinant human bone morphogenetic proteins (rhBMP-2) in the rat calvarial defect model. Eight-millimeter critical-size calvarial defects were created in 100 male Sprague-Dawley rats. The animals were divided into five groups of 20 animals each. The defects were treated with rhBMP-2/FFSS, rhBMP-2/FFSS/beta-TCP, FFSS and FFSS/beta-TCP carrier control or were left untreated as a sham-surgery control. Defects were evaluated by histologic and histometric parameters following a 2- and 8-week healing interval (10 animals/group/healing intervals). The FFSS/beta-TCP carrier group was significantly greater in new bone area at 2 weeks (p<0.05) and new tissue area at 2 and 8 weeks (p<0.01) relative to the FFSS carrier group. New bone and new tissue area in the rhBMP-2/FFSS/beta-TCP group were significantly greater than in the rhBMP-2/FFSS group at 8 weeks (p<0.01). On histologic observation, FFSS remnants were observed at 2 weeks, but by 8 weeks, the FFSS appeared to be completely resorbed. rhBMP-2 combined with FFSS/beta-TCP produced significantly more new bone and new tissue formation in this calvarial defect model. In conclusion, FFSS/beta-TCP may be considered as an available carrier for rhBMP-2.

Animals↗

PubMed2006

Effect of calcium phosphate glass on bone formation in calvarial defects of Sprague-Dawley rats.

The purpose of this study was to investigate the bone regenerative effect of calcium phosphate glass in vivo. We prepared two different sizes of calcium phosphate glass powder using the system CaO-CaF2-P2O5-MgO-ZnO; the particle size of the powders were 400 microm and 40 microm. 8 mm calvarial critical-sized defects were created in 60 male Sprague-Dawley rats. The animals were divided into 3 groups of 20 animals each. Each defect was filled with a constant weight of 0.5 g calcium phosphate glass powder mixed with saline. As controls, the defect was left empty. The rats were sacrificed 2 or 8 weeks after postsurgery, and the results were evaluated using radiodensitometric and histological studies; they were also examined histomorphometrically. When the bigger powders with 400 microm particle were grafted, the defects were nearly completely filled with new-formed bone in a clean healing condition after 8 week. When smaller powders with 40 microm particle were transplanted, new bone formation was even lower than the control group due to a lot of inflammatory cell infiltration. It was concluded that the prepared calcium phosphate glass enhanced the new bone formation in the calvarial defect of Sprague-Dawley rats and it is expected to be a good potential materials for hard tissue regeneration. The particle size of the calcium phosphate was crucial; 400 microm particles promoted new bone formation, while 40 microm particles inhibited it because of severe inflammation.

Animals↗

PubMed2006

Maxillary sinus septa: prevalence, height, location, and morphology. A reformatted computed tomography scan analysis.

BACKGROUND: The sinus lift technique may be difficult to perform if an aberrant sinus anatomy is encountered during surgical exposure, such as when a septum is present on the sinus floor. The objective of this study was to determine the prevalence, size, location, and morphology of maxillary sinus septa in the atrophic/edentulous and non-atrophic/dentate maxillary segments. METHODS: The sample population consisted of 100 patients (41 women and 59 men, with a mean age of 50 years, ranging between 19 and 87 years) for whom treatment was being planned for implant-supported restorations. Reformatted computerized tomograms (CT) from 200 sinuses were analyzed using imaging software. RESULTS: The prevalence of one or more septa per sinus was found to be 26.5% (53/200), 31.76% (27/85), and 22.61% (26/115) in the overall study population and the atrophic/edentulous and the non-atrophic/dentate maxillary segments, respectively. In the analysis of the anatomic location of the septa within the sinus, it was revealed that 15 (25.4%) were located in the anterior region, 30 (50.8%) in the middle region, and 14 (23.7%) in the posterior region. The measured heights of the septa varied among the different areas. The mean heights of the septa were 1.63 +/- 2.44, 3.55 +/- 2.58, and 5.46 +/- 3.09 mm in the lateral, middle, and medial areas, respectively. CONCLUSIONS: It can be inferred that there is a wide anatomical variation in the prevalence, size, location, and morphology of maxillary sinus septa, irrespective of the degree of atrophy. Therefore, to prevent the likelihood of complications arising during sinus augmentation procedures, a thorough and extensive understanding of the anatomic structures inherent to the maxillary sinus is indispensable.

Adolescent↗

PubMed2006

The effects of interproximal distance between roots on the existence of interdental papillae according to the distance from the contact point to the alveolar crest.

BACKGROUND: This study investigated the existence of interdental papillae at certain distances from the contact point to the alveolar crest, depending on the interproximal distance between roots. METHODS: A total of 206 papillae from 80 patients were examined after the inflammation of the papillae had been minimized using non-surgical periodontal therapy. The existence of the interdental papillae was determined using the following categorization: 1) papillae were deemed to be absent if they did not extend all the way up to the contact point between the teeth; and 2) papillae were determined to be present if they filled up to the entire proximal space. The interproximal distance between roots and the distance from the contact point to the alveolar crest were measured when a full-thickness flap was used. The number of papillae present interproximally between roots, according to the distance from the contact point to the alveolar crest, was analyzed using the x2 analysis method, and the linear-by-linear association analysis method was used for trend analysis. RESULTS: The number of papillae that filled the interproximal space decreased with increasing distance from the contact point to the alveolar crest (P <0.05). In addition, the number of papillae that filled the interproximal space decreased with increasing interproximal distance between roots (P <0.05) and became more prominently decreasing with the increasing distance from the contact point to the alveolar crest (especially 4, 5, and 6 mm) (P <0.05). CONCLUSION: The results suggest that the interproximal distance between roots and the distance between the contact point and the alveolar crest have an independent and combined effect on the existence of interproximal papillae.

Adult↗

PubMed2005

Bone formation in calvarial defects of Sprague-Dawley rats by transplantation of calcium phosphate glass.

The purpose of this study was to investigate the bone-regenerative effect of calcium phosphate glass in vivo. We prepared amorphous calcium phosphate glass powder having a mean particle size of 400 microm in the system CaO-CaF2-P2O5-MgO-ZnO. Calvarial critical-sized defects (8 mm) were created in 60 male Sprague-Dawley rats. The animals were divided into an experimental group and control group of 30 animals each. Each defect was filled with a constant weight of 0.5 g calcium phosphate glass powder mixed with saline. As a control, the defect was left empty. The rats were sacrificed 2, 4, or 8 weeks postsurgery, and the results evaluated using radiodensitometric and histological studies; they were also examined histomorphometrically. When the calcium phosphate glass powders with 400-microm particles were grafted, the defects were nearly completely filled with new-formed bone in a clean healing condition after 8 weeks. It was observed that the prepared calcium phosphate glass enhanced new bone formation in the calvarial defect of Sprague-Dawley rats and could be expected to have potential for use as a hard tissue regeneration material.

Animals↗

PubMed2005

Effects of chitosan nonwoven membrane on periodontal healing of surgically created one-wall intrabony defects in beagle dogs.

The purpose of this study was to investigate the periodontal regenerative effects of a chitosan nonwoven membrane applied to surgically created preclinical one-wall intrabony defects in beagle dogs. One-wall intrabony defects (4 x 4 x 4 mm) were surgically created bilaterally in the mandibular second and fourth premolars of six beagle dogs. The surgical control group received a flap operation only. The resorbable-membrane (RM) group was treated with resorbable membrane. The chitosan-nonwoven-membrane (CNWM) group was treated with chitosan nonwoven membrane. The amount of junctional epithelium migration and the amount of connective tissue adhesion did not show any statistically significant differences among the groups. However, the amount of suprabony cementum regeneration, intrabony cementum regeneration, and alveolar bone regeneration showed significant differences (p < 0.05) between CNWM site group and control group. The results demonstrate the regenerative effects of the chitosan nonwoven membrane in one-wall intrabony defects of beagle dogs. The chitosan nonwoven membrane has the potential to support the cementum and bone regeneration, possibly by providing the conditions needed for guided tissue regeneration in the one-wall intrabony periodontal defects of beagle dogs.

Animals↗

PubMed2005

Ectopic bone formation associated with recombinant human bone morphogenetic proteins-2 using absorbable collagen sponge and beta tricalcium phosphate as carriers.

The ectopic bone formation of recombinant human bone morphogenetic protein-2(rhBMP-2) was evaluated using absorbable collagen sponges (ACS) and beta tricalcium phosphate (beta-TCP) as carriers in a rat subcutaneous assay model. Subcutaneous pockets were created on the back of rats. The pockets were implanted with rhBMP-2/ACS, rhBMP-2/beta-TCP, ACS alone, and beta-TCP alone. The rats were sacrificed at 2 or 8 weeks for histological and immunohistochemical evaluation. At 2 weeks, bone formation was evident in both the rhBMP-2/ACS and rhBMP-2/beta-TCP sites. At 8 weeks, the quantity of the new bone with a more advanced stage of remodeling had increased further in the rhBMP-2/beta-TCP sites. However, the newly formed bone observed at 2 weeks was not found in the rhBMP-2/ACS sites. On immunohistochemical observation, osteopontin staining was observed on both the rhBMP-2/ACS (2 weeks) and rhBMP-2/beta-TCP (2 and 8 weeks) sites. Osteocalcin was not detected in any of the samples. The lack of space-providing capacity of ACS may be one of the major factors responsible for its failure to maintain the newly induced bone. Therefore, a carrier for BMPs should provide space for bone formation and maturation during the more advanced healing stages.

Absorbable Implants↗

PubMed2005

Periodontal healing in one-wall intra-bony defects in dogs following implantation of autogenous bone or a coral-derived biomaterial.

AIM: Autogenous bone grafts and bone biomaterials are being used as part of protocols aiming at reconstruction of periodontal defects. There is a limited biologic information on the effect of such materials on periodontal healing, in particular aberrant healing events that may prevent their general use. The objective of this study was, using histological techniques, to evaluate periodontal healing with focus on root resorption and ankylosis following implantation of autogenous bone and a coral-derived biomaterial into intra-bony defects in dogs. METHODS: One-wall intra-bony periodontal defects were surgically created at the distal aspect of the second and the mesial aspect of the fourth mandibular premolars in either right or left jaw quadrants in four Beagle dogs. Each animal received particulated autogenous bone and the resorbable calcium carbonate biomaterial into discrete one-wall intra-bony defects. The mucoperiosteal flaps were positioned and sutured to their pre-surgery position. The animals were euthanized 8 weeks post-surgery when block sections of the defect sites were collected and prepared for qualitative histological analysis. RESULTS: There were no significant differences in periodontal healing between sites receiving autograft bone and the coral-derived biomaterial. A well-organized periodontal ligament bridging new bone and cementum regeneration was observed extending coronal to a notch prepared to delineate the apical extent of the defect. Osteoid and bone with enclosed osteocytes were formed onto the surface of both autograft and coral particles. Although small resorption pits were evident in most teeth, importantly none of the biomaterials provoked marked root resorption. Ankylosis was not observed. CONCLUSION: Particulated autogenous bone and the coral-derived biomaterial may be implanted into periodontal defects without significant healing aberrations such as root resorption and ankylosis. The histopathological evaluation suggests that the autogenous bone graft has a limited osteogenic potential as demonstrated in this study model.

Animals↗

PubMed2005

The correlation between the bone probing, radiographic and histometric measurements of bone level after regenerative surgery.

BACKGROUND AND OBJECTIVE: The most accurate method of assessing bone level is to elevate the flap and measure the bone level directly. However, this method causes discomfort to the patient and can damage the tissues. Therefore, many studies have been conducted to find an alternative method that can be used to assess the bone level clinically with accuracy and reliability. In the present study, we evaluated the clinical reliability and accuracy of bone probing and radiographic measurements, by comparing the bone levels obtained by both of these measurement techniques with the histometrically confirmed bone levels, after four different kinds of regenerative therapy. METHODS: Twenty-four intrabony defects (4 x 4 mm one-wall intrabony defects) were surgically created bilaterally in the mandibular second and fourth premolars of six beagle dogs. The control group underwent a conventional flap operation. The graft group was treated with calcium phosphate glass only, the guided tissue regeneration group was treated with guided tissue regeneration only, and the graft + guided tissue regeneration group was treated with calcium phosphate glass and guided tissue regeneration. Bone probing and radiographic measurements were performed to assess the bone level 8 weeks after the operation and then the subjects were killed to perform the histometric measurements. The correlation between the bone probing depths and the histometric bone levels, and that between the radiographic bone levels and the histometric bone levels were analyzed by Spearman's rank correlation analysis. The statistical significance with respect to the type of regenerative therapy was analyzed by the Kruskal-Wallis test. RESULTS: The difference between the bone probing depth and the histometric bone level measurements was 0.14, and that between the radiographic bone level and histometric bone level was 0.6. The coefficient of correlation between the bone probing depth and the histometric bone level was 0.90, and that between the radiographic bone level and the histometric bone level was 0.73. The type of regenerative therapy had no significant effect on the difference between the histometric bone level and the other measurements. CONCLUSION: The results of the present study suggest that the bone probing measurement may be a reliable method for the assessment of the actual bone level following any type of periodontal regenerative therapy.

Alveolar Bone Loss↗

PubMed2005

The effects of a bioabsorbable barrier membrane containing safflower seed extracts on periodontal healing of 1-wall intrabony defects in beagle dogs.

BACKGROUND: Recently, there has been much research done into the regenerative potential of materials used in oriental medicine. In several studies, evidence was found that these materials have an effect on bone regeneration. Among these materials, safflower seeds are of particular interest as they have been used for the treatment of blood stasis, bone fracture, and osteoporosis in traditional Korean medicine. In addition, they are known to have anti-inflammatory effects. The objective of this study is to evaluate the periodontal tissue regenerative effects of a bioabsorbable barrier membrane (polylactide glycolic acid electro-spun non-woven membrane) containing safflower seed extracts applied to surgically created 1-wall intrabony defects in beagle dogs. METHODS: One-wall intrabony defects were surgically created bilaterally at the mesial and distal sides of the mandibular second premolars and mesial side of the fourth premolars. These defects were randomly assigned either to the surgical control group which received a flap operation only or to one of two experimental groups consisting of defects which received a guided tissue regenerative procedure with either a bioabsorbable membrane (PLGA) or a bioabsorbable membrane containing safflower seed extracts (SSE/PLGA). The dogs were sacrificed 8 weeks after the operation, and a comparative histological examination was done. RESULTS: The new cementum formation was 2.49+/-0.41 mm in the surgical control group, 3.22+/-0.35 mm in the PLGA group, and 3.67+/-0.82 mm in the SSE/PLGA group. The extent of new cementum formation in barrier groups was significantly different from the surgical control group (P <0.05). The amount of intrabony cementum was 1.75+/-0.06 mm, 2.40+/-0.33 mm, and 2.70+/-0.81 mm for the surgical control group, the PLGA group, and the SSE/PLGA group, respectively; the amount of infrabony cementum in the barrier groups was significantly different from the surgical control group (P<0.05). The value of the suprabony cementum was 0.73+/-0.48 mm, 0.82+/-0.21 mm, and 0.97+/-0.09 mm for the surgical control group, the PLGA group, and the SSE/PLGA group, respectively, with no significant differences being observed among the treatments. The amount of new alveolar bone formation was 1.74+/-0.25 mm, 2.36+/-0.30 mm, and 2.64+/-0.74 mm for the surgical control group, the PLGA group, and the SSE/PLGA group, respectively, with a significant difference exhibited between the surgical control group and other groups (P <0.05). Superficial root resorption was often observed, but ankylosis was not present. CONCLUSION: Our results suggest that surgical application of polylactide glycolic acid non-woven membrane with or without safflower seed extract could promote the regeneration of alveolar bone and cementum in intrabony periodontal defects.

Absorbable Implants↗

PubMed2005

Effect of recombinant human bone morphogenetic protein-2, -4, and -7 on bone formation in rat calvarial defects.

BACKGROUND: Currently, more than 20 bone morphogenetic proteins (BMPs) have been identified, and many trials have been carried out using recombinant human BMPs (rhBMPs) for bone tissue engineering. However, comparative analyses on bone formative activities of rhBMP using a preclinical model have been limited. Therefore, the aim of this study was to evaluate and compare the osteogenic potential of rhBMP-2, -4, and -7 delivered with absorbable collagen sponge (ACS) upon early (2 weeks) and complete (8 weeks) wound healing phases in a critical sized rat calvarial defect model. METHODS: Eight-millimeter critical sized calvarial defects were created in 30 male Sprague-Dawley rats. The animals were divided into three groups of 10 animals each. The defects were treated with 0.025 mg/ml rhBMP-2/ACS, rhBMP-4/ACS, or rhBMP-7/ACS. The rats were sacrificed at either 2 (five rats) or 8 (five rats) weeks after surgery, and the results were evaluated histologically, histomorphometrically, and immunohistometrically. RESULTS: The surgical implantation of rhBMP-2/ACS, rhBMP-4/ACS, or rhBMP-7/ACS resulted in enhanced local bone formation in the rat calvarial defect model at both 2 and 8 weeks. The amount of defect closure, new bone area, and bone density were similar in the three groups at each time point (P > 0.05). In terms of bone density and new bone area, there were statistically significant differences between results obtained at 2 weeks and those obtained at 8 weeks in all groups (P < 0.05). Two-way analysis of variance (ANOVA) revealed that there was no correlation between the time and conditions (P > 0.05), but time was found to have a strong influence on defect closure, new bone area, and bone density (P < 0.05). Irrespective of rhBMP type, positive immunoreactions of osteopontin (OPN) and osteocalcin (OCN) were evident at 2 and 8 weeks. Intense OPN and OCN staining was observed near the newly formed bone as well as in some cells within the new bone. CONCLUSIONS: Within the rhBMP types used, rhBMP concentration, and the observation interval, there appears to be no specific differences in bone regenerative potential. All rhBMPs used in this study may be considered effective factors for inducing bone formation.

Absorbable Implants↗

PubMed2005

Effect of a fibrin-fibronectin sealing system as a carrier for recombinant human bone morphogenetic protein-4 on bone formation in rat calvarial defects.

BACKGROUND: Bone morphogenetic proteins (BMPs) have been shown to play an important role in bone formation during development and wound healing. Despite there being good prospects for BMP applications, an ideal carrier system for BMPs has yet to be determined. The purpose of this study was to evaluate the possibility of a fibrin-fibronectin sealing system (FFSS) as a carrier for recombinant human BMP-4 (rhBMP-4) and to evaluate the genuine osteoconductive potential of the FFSS in a rat calvarial defect model. METHODS: An 8-mm, calvarial, critical-size osteotomy defect was created in each of 30 male Sprague-Dawley rats. Three groups of 10 animals each received rhBMP-4 (0.025 mg/ml) in the FFSS, FFSS control, or sham-surgery control. The groups were evaluated using histologic and histometric parameters following 2- and 8-week healing intervals (five animals per group per healing interval). RESULTS: Surgical implantation of rhBMP-4/FFSS resulted in enhanced local bone formation at 2 and 8 weeks. New bone formation was also evident in the FFSS control; however, the amount of defect closure, new bone area, and bone density was significantly greater in the rhBMP-4/FFSS group (P < 0.05). At 8 weeks, the quantity of the new bone was greater than that observed at 2 weeks, and the specimens showed a more advanced stage of remodeling and consolidation in both groups (P < 0.05). Only very limited bone formation was observed in the sham-surgery control. CONCLUSION: The results of the present study indicated that the FFSS has osteoconductive potential and may be employed as a carrier for BMPs.

Animals↗

PubMed2005

Non-invasive method to measure the length of soft tissue from the top of the papilla to the crestal bone.

BACKGROUND: In order to verify the results of interdental papilla regeneration, various methods of measuring the length of the papilla have been introduced. Invasive methods, such as bone probing under local anesthesia, might cause discomfort to the patients and possibly damage the delicate gingival unit. The purpose of the present study was to validate a method of measuring the length of the interdental papilla non-invasively, using radiopaque material and a periapical radiograph. METHODS: This study involved 142 interproximal papillae in 40 patients with chronic periodontitis. The distance between the radiopaque material and most coronal portion of the crestal bone was measured (radiographic length of papilla, RL). Bone probing at the interdental papilla was performed after local anesthesia (bone probing length, BPL). After flap elevation, the actual length of the papilla was measured (actual length of papilla, AL). A correlation analysis was performed between AL-RL and AL-BPL using Pearson's correlation coefficients. RESULTS: The correlation between AL-RL and AL-BPL was 0.903 and 0.931, respectively, both of which showed significance at the 0.01 level. CONCLUSION: The results of this study suggest that the noninvasive method using a radiopaque material and periapical radiograph could be utilized to measure the length of the interdental papilla.

Adult↗

PubMed2005

Effects of chitosan on human periodontal ligament fibroblasts in vitro and on bone formation in rat calvarial defects.

BACKGROUND: The purpose of this study was to evaluate the effect of chitosan on human periodontal ligament fibroblasts (hPDLF) in vitro and on bone formation in rat calvarial defects in vivo. METHODS: Fibroblast populations were obtained from individuals with a healthy periodontium and cultured in alpha minimum essential medium (MEM) for the control group. For the experimental groups, cells were cultured in alpha-MEM containing chitosan at concentrations of 0.01, 0.1, 1, or 2 mg/ml. The 3-(4,5-dimethyl-thiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, reverse transcription-polymerase chain reaction (RT-PCR) and the assay of alkaline phosphatase (ALPase) activity were performed. Eight mm calvarial critical-sized defects were created in 30 male Sprague-Dawley rats. The animals were divided into three groups of 10 animals each. The defects were treated with either chitosan/absorbable collagen sponge (ACS) or ACS alone in the experimental groups or were left untreated (surgical controls). The animals were sacrificed at 2 or 8 weeks post-surgery and the treatment outcomes were evaluated using histological and histomorphometric parameters. RESULTS: The chitosan-induced proliferative responses of the hPDLF reached a plateau at a concentration of 0.1 mg/ml (P <0.05). When the hPDLF were stimulated with 0.1 mg/ml chitosan, both the mRNA expression of type I collagen and the ALP activity were significantly up-regulated (P <0.05). The surgical implantation of chitosan/ACS enhanced the new bone formation at 8 weeks post-surgery and the amount of new bone formation of the chitosan/ACS group was significantly greater than that of both the ACS alone group and the surgical control group (P <0.01). The new bone area and defect closure in the chitosan/ACS group were significantly greater than those in the ACS control and sham surgery control groups at 8 weeks (P <0.01). However, the chitosan/ ACS group exhibited significantly less bone density than both the ACS control and the sham surgery control group at 8 weeks (P <0.01). CONCLUSIONS: Chitosan (0.1 mg/ml) enhanced the type I collagen synthesis and facilitated the differentiation into osteogenic cells. Chitosan reconstituted with ACS has a significant potential to accelerate the regeneration of bone in rat calvarial critical size defects.

Animals↗

PubMed2004

Proliferation, differentiation, and calcification of preosteoblast-like MC3T3-E1 cells cultured onto noncrystalline calcium phosphate glass.

The purpose of this study was to investigate calcium phosphate glass as a potential biomaterial for hard tissue repair. We prepared calcium phosphate glass using the system CaO-CaF(2)-P(2)O(5)-MgO-ZnO and cultured MC3T3-E1 cells onto the glass in alpha-MEM with beta-glycerophosphatase and ascorbic acid. Proliferation of the cells was determined to evaluate the biocompatibility of the prepared calcium phosphate glass. The alkaline phosphatase activity was measured to examine the osteoblast differentiation. Mineralization was evaluated by staining the calcium precipitates with Alizarin red. Culture onto the calcium phosphate glass exhibited no significant influence on cell proliferation compared to the polystyrene chosen as a control in this experiment (p > 0.05). The alkaline phosphatase activity in the experimental group, however, was enhanced by the calcium phosphate glass significantly at 10-18 days after incubation than that of the control group (p < 0.05). The promotion of bone-like tissue formation by the calcium phosphate glass was observed after 7 days and thereafter. The results of the present study indicate that the prepared calcium phosphate glass affects osteogenesis by increasing calcification of the extracellular matrix.

Alkaline Phosphatase↗

PubMed2004

Effects of sub-antimicrobial dose doxycycline therapy on crevicular fluid MMP-8, and gingival tissue MMP-9, TIMP-1 and IL-6 levels in chronic periodontitis.

OBJECTIVE: To investigate whether sub-antimicrobial dose doxycycline (SDD) therapy for 120 d in chronic adult periodontitis patients had significant effects on gingival crevicular fluid (GCF) matrix metalloproteinase-8 (MMP-8) levels, and on gingival tissue MMP-9, tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) and interleukin-6 (IL-6) levels. BACKGROUND: Tetracycline can significantly inhibit MMP activity in GCF and in gingival tissue, even in much lower dosage then a traditional antimicrobial dosage used in conventional therapy. Sub-antimicrobial dose doxycycline (SDD) therapy has been shown to reduce periodontal disease activity to control MMP and pro-inflammatory cytokines. METHODS: A total of 32 patients with incipient to moderate (probing pocket depth approximately 4-7 mm) chronic adult periodontitis were included in the study. Subjects were randomly assigned to two groups. After scaling and root planning (SRP), the SRP + SDD group received SDD, 20 mg bid, whereas the SRP + placebo group received placebo, 20 mg bid. In the follow-up, efficacy measures included the change in probing pocket depth (PD), clinical attachment level (CAL), bleeding on probing (BOP) and gingival crevicular fluid MMP-8 levels, gingival tissue MMP-9, TIMP-1 and IL-6 levels from baseline to 120 d. RESULTS: After 120 d, PD and CAL improved significantly in the SRP + SDD group. Initial MMP-8 levels for the SRP + SDD group and the SRP + placebo group were 407.13 +/- 114.45 ng/ml and 378.71 +/- 189.39 ng/ml, respectively, with no statistical difference between the two groups. MMP-8 levels for the SRP + SDD group and the SRP + placebo group were: 235.35 +/- 134.58 ng/ml and 364.04 +/- 219.27 ng/ml at 30 d; 157.50 +/- 95.95 ng/ml and 236.60 +/- 186.16 ng/ml at 60 d; 102.70 +/- 67.64 ng/ml and 208.56 +/- 124.54 ng/ml at 90 d; and 63.77 +/- 53.33 ng/ml and 229.13 +/- 168.09 ng/ml at 120 d, respectively. The amount of decrease in MMP-8 levels for the SRP + SDD group was statistically significant compared to that for the SRP + placebo group, especially apparent at 120 d (p < 0.05). TIMP-1 levels in both groups increased from the baseline to 120 d with statistical significance (p-value < 0.05), but there was no significant difference between the two groups. Changes in MMP-9 and IL-6 levels were not statistically significant. CONCLUSION: Adjunctive SDD therapy can improve the clinical parameters and this clinical improvement is reflected by controlled level of MMP-8 in chronic adult periodontitis after the therapy.

Adult↗

PubMed2004

Inhibitory effects of green tea polyphenol (-)-epigallocatechin gallate on the expression of matrix metalloproteinase-9 and on the formation of osteoclasts.

BACKGROUND: Alveolar bone resorption is a characteristic feature of periodontal diseases and involves the removal of both the mineral and organic constituents of the bone matrix, which is caused by either multinucleated osteoclast cells or matrix metalloproteinases (MMPs). The gram-negative bacterium, Porphyromonas gingivalis has been reported to stimulate the activity and expression of several groups of MMPs, whereas (-)-epigallocatechin gallate (EGCG), the main constituent of green tea polyphenols, has been reported to have inhibitory effects on the activity and expression of MMPs. OBJECTIVES: In the present study, we investigated the effects of the green tea polyphenol, EGCG, on the gene expression of osteoblast-derived MMP-2, -9 and -13, stimulated by P. gingivalis, and on the formation of osteoclasts. METHODS: The effect of EGCG on the gene expression of MMPs was examined by treating mouse calvarial primary osteoblastic cells with EGCG (20 microM) in the presence of sonicated P. gingivalis extracts. The transcription levels of MMP-2, -9 and -13 were assessed by reverse transcription-polymerase chain reaction (RT-PCR). The effect of EGCG on osteoclast formation was confirmed by tartrate-resistant acid phosphatase (TRAP) staining in a co-culture system of mouse bone marrow cells and calvarial primary osteoblastic cells. RESULTS: Treatment with the sonicated P. gingivalis extracts stimulated the expression of MMP-9 mRNA and this effect was significantly reduced by EGCG, whereas the transcription levels of MMP-2 and MMP-13 were not affected by either the sonicated P. gingivalis extracts or EGCG. In addition, EGCG significantly inhibited osteoclast formation in the co-culture system at a concentration of 20 microM. CONCLUSIONS: These findings suggest that EGCG may prevent the alveolar bone resorption that occurs in periodontal diseases by inhibiting the expression of MMP-9 in osteoblasts and the formation of osteoclasts.

Analysis of Variance↗

PubMed2004

Surgical extrusion technique for clinical crown lengthening: report of three cases.

Although a number of techniques have been proposed for clinical crown lengthening procedures, all have some limitation in terms of function and esthetics. This report presents the clinical and radiographic results of a surgical extrusion technique for clinical crown lengthening. Atraumatic surgical extrusion using a specially designed instrument (Periotome) was performed in three cases in which it was expected that extensive resective osseous surgery would have to be used for crown lengthening. Full-thickness mucoperiosteal flaps were raised both labially and palatally. The tooth was carefully luxated and extruded to the desired position without damaging the marginal bone area or root apex. No rigid splint was applied. Clinical examinations performed for more than 1 year after surgery revealed probing depths < or = 3 mm around the teeth at all sites, without bleeding on probing. The teeth functioned normally, with near-normal mobility. Radiographs showed normal periodontal contour consistent with new bone formation in the periapical area. Radiographic analysis did not show any evidence of root or crestal bone resorption or endodontic problems. The technique presented could constitute an alternative surgical approach to performing crown lengthening; it does not induce functional or esthetic deformities, especially in the anterior region.

Adult↗