Biomedical subjects

Seong-Ho Choi

Publications and source records attributed to Seong-Ho Choi.

At least 37 records · Page 2Linked to original sources

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

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↗

PubMed2005

Alveolar ridge splitting: a new microsaw technique.

Narrow dentoalveolar ridges remain a serious challenge for the successful placement of endosseous implants. This case series describes a modification of previous ridge-splitting techniques using a microsaw blade. The approach enables treatment of ridges as thin as 2.5 mm at the alveolar crest and simultaneous placement of dental implants. In one extreme case reported here, where the crest width was less than 2.5 mm, a two-stage approach was used; implants were placed about 1 month after ridge expansion. In the 10 patients treated in this series, 27 dental implants were placed and achieved successful integration.

Alveolar Ridge Augmentation↗

PubMed2004

Retention behavior of C1-C6 aliphatic monoamines on anion-exchange and polymethacrylate resins with heptylamine as eluent.

Retention behavior of C1-C6, aliphatic monoamines (methylamine, ethylamine, propylamine, butylamine, amylamine and hexylamine) on columns (150 mm x 6 mm i.d.) packed with various anion-exchange resins (styrene-divinylbenzene (PS-DVB) copolymer-based strongly basic anion-exchange resin: TSKgel SAX, polymethacrylate-based strongly basic anion-exchange resin: TSKgel SuperQ-5PW and polymethacrylate-based weakly basic anion-exchange resin: TSKgel DEAE-5PW) and unfunctionized polymethacrylate resins (TSKgel G5000PW and TSKgel G3000PWXL) was investigated with basic solutions (sodium hydroxide and heptylamine) as the eluents. Due to strongly electrostatic repulsion (ion-exclusion effect) between these anion-exchange resins and these amines, peak resolution between these amines on these anion-exchange resin columns was unsatisfactory with both sodium hydroxide and heptylamine as the eluents. In contrast, these polymethacrylate resins were successfully applied as the stationary phases for the separation of these C1-C6 amines with heptylamine as eluent, because of both small hydrophobicity and small cation-exchange ability of these resins. Excellent simultaneous separation, highly sensitive conductimetric detection and symmetrical peaks for these C1-C6 amines were achieved on the TSKgel G3000PWXL column in 35 min with 5 mM heptylamine at pH 11.1 as the eluent.

Amines↗

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

Comparative study on the chiral separation of phenyl alcohols by capillary electrophoresis and liquid chromatography.

Structurally related phenyl alcohols were separated by capillary electrophoresis and liquid chromatography. A statistical experimental design was used in order to optimize the main electrophoretic parameters such as pH, concentration of selector and separation voltage in capillary electrophoresis (CE). Response surfaces were derived using the mathematical model and used for a selection of the optimal experimental conditions. Concentration of the chiral selector, the distance between the aromatic group and asymmetric center of the analytes, were identified as the factors influencing the complexation, selectivity and resolution. Experiments were also performed by high-performance liquid chromatography (HPLC) and the results of CE and HPLC were compared.

Benzyl Alcohols↗

PubMed2004

Effects of continuous and interrupted orthodontic force on interleukin-1beta and prostaglandin E2 production in gingival crevicular fluid.

The purpose of this study was to evaluate the effects of a light continuous force and an interrupted force with weekly reactivation on interleukin-1beta (IL-1beta) and prostaglandin E(2) (PGE(2)); possible interactions between these 2 potent mediators of the bone resorption process were assessed in vivo. Ten healthy young adults (mean age 20.6 years, 2 men, 8 women) with 4 premolars extracted were assessed. In each subject, 1 maxillary canine (E1) received continuous force with a nickel-titanium coil spring. The opposite canine (E2) received an interrupted force with a screw-attached retractor; the force was reactivated weekly by 2 turns of the screw. An antagonistic canine was used as a control. Gingival crevicular fluid was collected from the distal side of each tooth, 10 times in 3 weeks, and IL-1beta and PGE(2) levels were measured. For E1, the IL-1beta level showed a significant elevation at 24 hours and then decreased and maintained an insignificant but high mean concentration, compared with the control site. The PGE(2) level showed a significant elevation at 24 hours and then decreased. For E2, a significant elevation of IL-1beta level was observed at 24 hours and a greater significant elevation at 24 hours after the first reactivation, compared with the control sites. The PGE(2) level increased significantly at 24 hours and remained high for 1 week. The synergistic up-regulation of PGE(2) by appliance reactivation and secreted IL-1beta was not evident with either type of force after 1 week. Both experimental sites showed significant tooth movement compared with the control sites at 3 weeks; however, there was no significant difference between the 2 experimental sites. A well-controlled mechanical stress with timely reactivation can effectively upregulate IL-1beta secretion, but there might be limitations in increasing the mediator levels, because of the feedback mechanisms in vivo. In addition, the analysis of crevicular fluid is a useful method for assessing cellular response to orthodontic force in vivo.

Adolescent↗

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

Phase II study of gemcitabine combined with uracil-tegafur in metastatic pancreatic cancer.

OBJECTIVE: The single agent gemcitabine is the standard first-line treatment for advanced pancreatic cancer. Recent studies of a combination of gemcitabine and 5-fluorouracil (5-FU) revealed that survival data were superior to those with gemcitabine or 5-FU alone. The administration of oral uracil-tegafur (UFT) is more convenient and simulates the effect of a continuous or protracted infusion of 5-FU. Therefore, we conducted a phase II study of gemcitabine combined with UFT in metastatic pancreatic cancer patients and assessed the efficacy and the toxicity of the regimen. METHODS: Twenty-two pancreatic adenocarcinoma patients (18 males, 4 females) were enrolled from December 2000 to September 2002. The regimen consisted of gemcitabine 1,000 mg/m(2) once weekly for 3 consecutive weeks, and oral UFT 390 mg/m(2)/day (in 3 divided doses) on days 1-14. The cycle was repeated every 28 days. The objective tumor response was evaluated after 2 courses of chemotherapy. RESULTS: 82 cycles were administered in total, with a median of 3 cycles per patient (range 1-6 cycles). The median age was 52 years (range 28-69 years). Response to treatment could be assessed in all patients. The objective response rate was 22.7% (95% CI, 7.8-45.4) with no complete response and 5 partial responses. Four patients (18.2%) had stable disease and 13 patients (59.1%) had a progression. The median time to progression was 4.2 months (range 0.9-13.6). The median overall survival was 5.8 months (range 0.5-13.6). Of 10 patients eligible for the assessment of clinical benefit response, 4 (40%, 95% CI 12.2-73.8) showed clinical benefit. Among 21 patients with baseline CA 19-9 levels, CA 19-9 was reduced by 50% or more in 12 patients (57.1%). The chemotherapy was generally well tolerated and the most common grade 3-4 toxic side effects were neutropenia (18.2%), anemia (4.5%), and diarrhea (4.5%). CONCLUSIONS: The combination chemotherapy with gemcitabine and UFT in metastatic pancreatic cancer was tolerable for most patients but showed modest response rates and clinical benefit. However, a randomized phase III study should be conducted in order to further test the efficacy of the regimen.

Adenocarcinoma↗

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↗

PubMed2004

Effect of recombinant human bone morphogenetic protein-4 dose on bone formation in a rat calvarial defect model.

BACKGROUND: Bone morphogenetic proteins (BMPs) are being evaluated for periodontal and bone regenerative therapy. The objective of this study was to evaluate the effect of recombinant human bone morphogenetic protein-4 (rhBMP-4) dose on local bone formation in a rat calvaria defect model. METHODS: Calvarial, 8 mm diameter, critical-size osteotomy defects were created in 140 male Sprague-Dawley rats. Seven groups of 20 animals each received either 1) rhBMP-4 (2.5 microg) in an absorbable collagen sponge (ACS) carrier, 2) rhBMP-4 (5 microg)/ACS, 3) rhBMP-4 (2.5 microg) in a beta-tricalcium phosphate (beta-TCP) carrier, 4) rhBMP-4 (5 microg)/beta-TCP, 5) ACS or 6) beta-TCP carrier controls, or 7) a sham-surgery control, and were evaluated by histologic and histometric parameters following a 2- or 8-week healing interval (10 animals/group/healing interval). RESULTS: Surgical implantation of rhBMP-4/ACS and rhBMP-4/beta-TCP resulted in enhanced local bone formation at both 2 and 8 weeks. Within the dose range examined, rhBMP-4 did not exhibit an appreciable dose-dependent response. Defect closure was not significantly different between the rhBMP-4/ACS and rhBMP-4/beta-TCP groups. New bone area of the rhBMP-4/ beta-TCP group was significantly greater than that of the rhBMP-4/ ACS group; however, bone density in the rhBMP-4/ACS group was significantly greater than that in the rhBMP-4/beta-TCP group at 8 weeks (P < 0.05). CONCLUSIONS: rhBMP-4 combined with ACS or beta-TCP has a significant potential to induce bone formation in the rat calvaria defect model. Within the selected rhBMP-4 dose range and observation interval, there appeared to be no meaningful differences in bone formation.

Animals↗

PubMed2004

Periodontal repair in surgically created intrabony defects in dogs: influence of the number of bone walls on healing response.

BACKGROUND: The objective of this study was to histologically evaluate periodontal healing following flap surgery in intrabony periodontal defects to determine the influence of the number of bone walls on periodontal regeneration. METHODS: One-, 2-, and 3-wall intrabony periodontal defects were surgically produced at the proximal aspect of mandibular premolars in either right or left jaw quadrants in six beagle dogs. Mucoperiosteal flaps were positioned and sutured to their presurgery position following defect preparation. The animals were euthanized at 8 weeks post-surgery, and block sections of the defect sites were collected for histologic and histometric analysis. RESULTS: Bone and cementum regeneration was positively correlated to the number of bone walls limiting the intrabony periodontal defects. The junctional epithelium averaged (+/- SD) 1.5 +/- 0.2, 1.2 +/- 0.3, and 0.9 +/- 0.2 mm for the 1-, 2-, and 3-wall defects, respectively, with the 3-wall defects being significantly different from the 1-wall defects (P <0.05). Cementum regeneration averaged 1.2 +/- 0.6, 2.0 +/- 0.6, and 2.8 +/- 0.5 mm for the 1-, 2-, and 3-wall defects, respectively; all groups were significantly different from each other (P <0.05). Bone regeneration averaged 1.5 +/- 0.5, 1.7 +/- 0.6, and 2.3 +/- 0.5 mm for the 1-, 2-, and 3-wall defects, respectively, with the 3-wall defects being significantly different from the 1-wall defects (P <0.05). CONCLUSIONS: The results suggest that the number of bone walls is a critical factor determining treatment outcomes in intrabony periodontal defects. One- and 3-wall intrabony defects appear to be reproducible models to evaluate candidate technologies for periodontal regeneration.

Alveolar Bone Loss↗

PubMed2004

Inhibition of cyclosporin A-induced gingival overgrowth by azithromycin through phagocytosis: an in vivo and in vitro study.

BACKGROUND: The objective of the present study was to investigate the effect of cyclosporin A (CsA) and azithromycin (AZI) on collagen metabolism in the gingiva of rats. METHODS: Fifty 6-week-old male Sprague-Dawley (SD) rats (weight 120 to 150 g) were randomly distributed into five groups. All groups received various drugs via gastric feeding for 7 weeks. The first group (Mo group) received mineral oil for 7 weeks as a control; the CsA group received CsA in mineral oil for 7 weeks (dosage 30 mg/kg); the CsA/Mo group received CsA in mineral oil for 6 weeks and mineral oil only for the seventh week; the CsA/AZI group received CsA in mineral oil for 6 weeks and AZI (dosage 10 mg/kg) in mineral oil simultaneously with CsA in the seventh week; and the Mo/AZI group received mineral oil for 6 weeks and AZI in mineral oil for the seventh week. All animals were sacrificed for clinical and histological analyses. Gingival fibroblasts were cultured at the fourth passage, and the amount of collagen was measured. Type I collagen and collagenase mRNA were measured by reverse transcription-polymerase chain reaction. Collagen phagocytosis assay also was performed. RESULTS: Clinically, CsA induced gingival overgrowth in rats, whereas AZI reduced gingival overgrowth. Histological results of the CsA group showed a marked increase of tissue volume compared to the other groups. High collagen amounts were found when gingival overgrowth was induced. However, type I collagen mRNA and collagenase mRNA expressions did not statistically differ among groups. Phagocytosis assay showed that CsA decreased phagocytic activity of gingival fibroblasts, whereas AZI increased the activity. These results suggest that the induction and reduction of CsA-induced gingival overgrowth were closely associated with phagocytic activity. CONCLUSION: Cyclosporin A decreases collagen degradation by lowering phagocytic activity of rat gingival fibroblasts. Azithromycin partially compensates for this lowered phagocytic activity.

Animals↗

PubMed2004

Effect of the carbon dioxide laser on the clinical parameters and crevicular IL-1beta when used as an adjunct to gingival flap surgery.

OBJECTIVE: This study evaluated the effect of a carbon dioxide (CO2) laser treatment on the clinical parameters and crevicular Interleukin-1 (IL-1beta) levels when used in combination with gingival flap surgery. METHODS: Twelve patients with moderate to advanced periodontitis were selected for this study. Three quadrants in each patient were randomly assigned to one of the following study groups: 1) flap surgery only as the (control); 2) flap surgery and laser treatment using an energy level of 0.8 W as (group 1); 3) flap surgery and laser treatment using an energy level of 0.5 W as (group 2). The gingival crevicular fluid (GCF) was collected at the baseline and biweekly for 6 weeks and the amount of IL-1beta concentration in the sulcular fluid was measured using an enzyme-linked immunosorbent assay. The clinical parameters such as the probing pocket depth, the clinical attachment level, the gingival recession and the bleeding on probing were recorded at the baseline, 3, 6 months. RESULTS: Marked reductions of the bleeding on probing, the probing pocket depth, the clinical attachment level and a reduction in the crevicular IL-1beta concentration were found in all groups. However, the differences between the groups in terms of bleeding on probing and the probing pocket depth were not significant (p<0.05). The clinical attachment level and the crevicular IL-1beta level were significantly lower in group 1 (0.8 W) than in the control (p<0.05). CONCLUSION: The additional use of a carbon dioxide laser on the root surface during gingival flap surgery may enhance the clinical attachment and reduce the crevicular IL-1beta concentration.

Adult↗

PubMed2003

Split flow and bypass flow systems for monolithic capillary columns in liquid chromatography.

Split flow and bypass flow systems were assembled using Nano Y Connectors with low dead volume commercially available for capillary liquid chromatography (LC). The split ratio could be controlled by changing the dimension of restriction tubing and applied back pressure to the restriction tubing. The split flow system allowed us to use valve injectors and pumps commercially available for capillary LC. The reproducibility of the present split flow system was acceptable. The relative standard deviation for six successive measurements was 0.4% for the retention time, whereas that for the peak height and peak area was 1-3% depending on the analytes. The bypass flow system uses two Nano Y Connectors, where the eluent split at the first Nano Y Connector, which is located in the inlet of the separation column, is merged again into the effluent from the column at the second Nano Y Connector. The bypass flow system could avoid on-column detection and allowed us to use flow cells, leading to an approximate three times improvement in signal-to-noise. The present flow systems were evaluated by using aromatic hydrocarbons and alkylbenzenes as test analytes.

Chromatography, Liquid↗