The sustaining effect of three polymers on the release of chlorhexidine from a controlled release drug device for root canal disinfection / 대한치과보존학회지

The aim of this in vitro study was to evaluate the suitability of using chitosan, poly (lactide-co-glycolide) (PLGA), and polymethyl methacrylate (PMMA) to control the release of chlorhexidine digluconate (CHX) from a prototype of controlled release drug device (CRD) for root canal disinfection. Four different prototypes with different formulations were prepared. Group A (n = 12); The device (absorbent paper point) was loaded with CHX as control. Group B (n = 12); same as group A, but the device was coated with chitosan. In Groups C and D, the device was treated in the same way as group A and then coated three times with 5% PMMA (Group C, n = 12), or coated three times with 3% PLGA (Group D, n = 12). The devices were randomly allocated to experimental groups of 12 each. All CRD prototypes were soaked in 3 mL distilled water. The concentrations of CHX were determined using a UV spectrophotometer. The surface characteristics of each prototype were observed using a scanning electron microscope. The result showed that release rate of CHX was the greatest in the non-coated group, followed by the chitosan-coated group, the PLGA-coated group, and the PMMA-coated group (P < 0.05). Pores were observed on the surface of the prototypes that were coated with PLGA and PMMA. When the pore size was smaller, the release rate was lower. This data indicate that polymer coating can control the release rate of CHX from the CRD prototypes.

The Effects of Calcium Phosphate Glass on Mouse Calvarial Cell / 대한치주과학회지

The goal of periodontal treatment is not only to arrest the progression of the disease but also to promote the functional, esthetic regeneration of the periodontium. Flap operation, bone graft, guided tissue regeneration, growth factors and bone morphogenetic protein have been used for this purpose. Among these techniques of regeneration, alloplastic graft, especially calcium phosphate is getting more attention recently. The purpose of this study was to evaluate the effects of calcium phosphate glass on mouse calvarial cell in vitro. The toxicity of calcium phosphate glass was measured using MTT assay, the synthesis of collagen was measured using collagen assay, and ALP activity was measured. The experimental groups were cultured with calcium phosphate glass(both AQ-, and HT-CPG) in concentration of 0.01, 0.02, 0.1, 0.2g/ml. The results are as follows 1. In concentrations not exceeding 0.02g/ml, both the groups(AQ-CPG, HT-CPG) didn't show any toxicity on mouse calvarial cell(p<0.05). 2. In both the experimental groups are the concentration of 0.02g/ml, collagen expressions were significantly up-regulated (p<0.05). 3. In both the experimental groups are the concentration of 0.02g/ml, ALP activity was not significantly upregulated, but ALP activity in both experimental groups were greater than control group(p<0.05). The results suggested that the use of calcium phosphate glass may promotes periodontal regeneration. Ongoing studies are necessary in order to determine their regeneration effects.

The effects of polylactic/polyglycolic copolymer (PLA/PGA) membrane on the healing of 1-wall intrabony defects in beagle dogs / 대한치주과학회지

The goal of periodontal treatment is regeneration of the periodontium. Bone graft and absorbable PLA/PGA membrane have been used for this purpose. In this study, 4x4mm 1-wall intrabony defects were surgically created bilaterally in the mandible of five male beagles. The control group went through a conventional flap operation, while the experimental group I was treated with absorbable PLA/PGA membranes only, group II was treated with absorbable membrane and calcium phosphate. The results are the following : 1. The defect height was 4.82+/-0.45mm in the control group, 4.93+/-0.79mm in the experimental I group, and 4.92+/-0.62mm in the experimental II group. There was no statistically significant difference among 3 groups(P<0.05). 2. The amount of junctional epithelium migration was 30.90+/-9.92% of the defect height in the control group, 39.16+/-7.51% in the experimental I group, and 38.68+/-12.22% in the experimental II group. There was no statistically significant difference among 3 groups(P<0.05). 3. The amount of connective tissue adhesion was 36.38+/-9.03% in the control group, 14.73+/-3.93% in experimental I group, and 27.87+/-9.70% experimental II group. Experimental group I was a statistically significantly different from control group(P<0.05). 4. The amount of new cementum regeneration was 32.92+/-10.51%, 50.04+/-7.61%, and 39.62+/-12.14% for the control, experimental I, and experimental II group respectively. Experimental group I was a statistically significantly different from control group(P<0.05). 5. The amount of new alveolar bone regeneration was 27.24+/-7.49%, 40.75+/-8.03%, and 36.47+/-15.11% for the control, experimental I, and experimental II group respectively. Experimental group I was a statistically significantly different from control group(P<0.05). The results suggest that the use of PLA/PGA membrane in 1-wall intrabony defect of beagle dogs may promote periodontal regeneration. Further studies are required to determine their regeneration effects.

The correlation of bone probing, radiographic and histometric measurements / 대한치주과학회지

The most accurate method to assess bone level is the histometric measurement. However it causes discomfort in patients and damage to the regenerated tissues. in the present study, we used 4 type regenerative therapies. The present study evaluated the clinical reliability and accuracy of bone probing measurements and radiographic bone level in the assessment of bone level by comparing those results with histometric confirmed bone level. Twentyfour(24) intrabony defects(4x4mm 1-wall intrabony defects) were surgically created in the mandibular second and fourth premolars of 6 beagle dogs. The control group underwent a conventional flap operation. Experimental group 1 was treated with calcium phosphate glass only, and while experimental group 2 was treated with GTR and experimental group 3 was treated with calcium phosphate glass and GTR. The subjects were sacrificed 8 weeks after the operation and a bone probing measurements, radiographic measurement and histometric measurement was performed. The correlation between bone probing measurements(BP) and histometric measurement(HL), and radiographic measurement(RL) and histometric measurement(HL) were analyzed with Spearman's rank correlation analysis and the statistical significance with respect to the type of regenerative therapies was analyzed with the Kruskal Wallis test. The coefficeint of correlation to HL was 0.73 for RL and 0.90 for BP. The type of regenerative therapies had no significant effect on the difference between HL and other measurements. The results of this study suggests that bone probing measurements most closely represents actual bone level. So bone probing measurements may be a good clinical method for assessing the bone level following any type of periodontal regenerative therapies.