Non-coated Group Research Articles

Effect of Resin Coating on Adhesion of Composite Crown Restoration

The purpose of this study was to evaluate the effect of a resin coating technique on the microtensile bond strength (microTBS) of resin cement to dentin in composite crown restorations. Crown preparations were done on human molars. A resin coating material, Hybrid Bond, was immediately applied to the prepared dentin and light-cured, while the tooth without resin coating acted as the control. An impression of the resin-coated tooth was taken, and a composite crown fabricated on the working cast. The composite crown was then bonded with a resin cement, Chemiace II. MicroTBSs were measured at a crosshead speed of 1 mm/min, and the resin-coated group yielded significantly higher microTBSs than the non-coated group (p < 0.05). In terms of microTBS values between the axial and occlusal surfaces, no regional differences in resin-dentin bond strength were detected (p < 0.05). It was concluded that resin coating with Hybrid Bond significantly improved the microTBS of resin cement to dentin in composite crown restorations.

Effects of poly-2-methoxyethylacrylate (PMEA)-coating on CPB circuits

Objectives. In this study, the immuno- and neuroprotective effect of a novel cardiopulmonary bypass coating was investigated. Design. Thirty nine patients scheduled for elective coronary artery bypass grafting were randomly assigned to either PMEA-coated (n = 19) or non-coated CPB circuits (n = 20). Pericardial suction blood was separated and retransfused only if needed at the end of operation. Neurocognitive functions were examined preoperatively and 7–10 days postoperatively using a standard neuropsychological test battery. Assuming an inflammatory etiology, the most cogent inflammatory markers were perioperatively analyzed. Results. Postoperatively, patients of the PMEA-coated group performed better in Go/NoGo and Mini-Mental-test than patients of the non-coated group (p < 0.04). Other neurocognitive testing did not reveal significant differences between the groups. Although most inflammatory parameters showed a significant intraindividual increase during or shortly after CPB, there was no difference in inflammatory alteration between the groups. Conclusions. PMEA-coating of cardiopulmonary bypass surfaces revealed some minor benefits in preservation of neurocognitive functions after surgery. The immediate inflammatory response remained mostly unaffected. Suction blood separation may additionally contribute to proper postoperative outcome.

Fluorinated diamond‐like carbon as antithrombogenic coating for blood‐contacting devices

Diamond-like carbon (DLC) is being considered for widespread clinical use as a surface coating for cardiovascular devices. We synthesized fluorinated DLC (F-DLC) coatings in order to create a more hydrophobic surface with improved antithrombogenicity and flexibility when compared with conventional DLC coatings by combining the inertness of DLC films with the advantage of fluorination. The purpose of this study was to evaluate the in vitro hemocompatibility and in vivo biocompatibility of the F-DLC coating for medical devices. The in vitro whole blood model confirmed that platelet loss was lower in the F-DLC group than in the noncoated group (SUS316L), which suggests the adhesion of a smaller number of platelets to F-DLC-coated materials. Furthermore, the biomarkers of mechanically induced platelet activation (beta-thromboglobulin) and activated coagulation (thrombin-antithrombin-three complex) were markedly reduced in the F-DLC-coated group. In vivo rat implant model studies revealed no excessive local and systemic inflammatory responses in the F-DLC group. The thickness of the fibrous tissue capsule surrounding the F-DLC-coated disk was almost equal to that of the noncoated SUS316L disk, which has the favorable biocompatibility for metallic implant materials. F-DLC coating thus appears to be a promising candidate for use as a coating material in blood-contacting devices.

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

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 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 (Texan MedTech). In Groups C and D, the device was treated in the same way as group A and then coated 3 times with 5% PMMA (Group C, n = 12, Aldrich), or coated 3 times with 3% PLGA (Group D, n = 12, Sigma). The devices were randomly allocated to experimental groups of 12 each. All the prototypes of controlled release drug device 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 noncoated 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. These data indicate that polymer coating can control the release rate of CHX from the prototypes of controlled release drug device.

Brain Injury and Neuropsychological Outcome After Coronary Artery Surgery Are Affected by Complement Activation

The impact of the postoperative inflammatory response on the central nervous system after cardiac surgery is uncertain. The goal of the study was to evaluate the role of complement activation on cellular brain injury in patients undergoing coronary artery bypass grafting. In addition, neuropsychological functioning was assessed. We randomly assigned 30 patients to undergo surgery using either standard noncoated or heparin-coated extracorporeal circuits. Closed cardiopulmonary bypass and controlled suctions of pericardial shed blood were standardized in both groups. Complement activation and cellular brain injury were assessed by measuring sC5b-9 and protein s100beta. Neuropsychometric tests were performed at least 2 weeks before operation and at discharge. They served to calculate z scores of cognitive domains and changes in neuropsychological functioning. Peak value of sC5b-9 at the end of cardiopulmonary bypass in the noncoated group was significantly higher than in the heparin-coated group (p = 0.005). Changes in the heparin-coated group were not significant. Glial injury started after initiation of surgery and peaked at the end of cardiopulmonary bypass with significantly higher concentration of s100beta in the noncoated than in the heparin-coated group (p = 0.008). Values of s100beta and of sC5b-9 were significantly correlated (p = 0.03). Although no statistically significant between group difference was detected, z scores of attention and flexibility or executive functions were lowered postoperatively within the noncoated group (p = 0.033 and p = 0.028), whereas z scores were unchanged within the heparin-coated group. Inhibition of complement activation by heparin-coated cardiopulmonary bypass reduced brain cell injury and was associated with preserved neuropsychological functioning after coronary artery bypass grafting.

Characterization and in vivo evaluation of calcium phosphate coated cp-titanium by dip-spin method

Calcium phosphate ceramics like hydroxyapatite (HA) and tricalcium phosphate (TCP) are good candidates for bone substitutes due to their chemical similarity to bone minerals. Additionally, the biodegradation property of bone substitutes may allow the organism to replace the foreign material by fully functional new bone in a balanced time schedule. Thus, the coating of biodegradable calcium phosphate ceramics on dental implants was conducted in this study to enhance the biocompatibility and eliminate the long-term adverse effects of HA coated implants. First, biodegradable calcium metaphosphate(CMP) sol was prepared and then coated on cp-Ti substrates by a dip-spin coating technique. The coated specimens were heat-treated at 600 °C for 6 h. CMP coated layer on cp-Ti was smooth and uniform with fine grains. It is observed that bone-to-implant contact area of CMP coated specimen at both 2 and 6 weeks was significantly higher than that of non-coated group. The biocompatibility and cytotoxicity of the CMP coated specimen were better than those of the non-coated specimen. Therefore, the CMP coating on cp-Ti is a good candidate for improving bone-to-implant osseointegration, although it is difficult to extrapolate in vitro results directly to in vivo situation.

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

ABSTRACT Ⅰ. Introduction Complete debridement and thorough disinfection ofinfected root canals are considered mandatory for thesuccess of root canal treatment 1) . However, canalpreparation and irrigation are not always effective ineliminating total microflora from the root canal sys-tem 1-3) . Traditionally, calcium hydroxide has provento be an excellent intracanal medicament for infectedroot canals 4,5) . However, it is known to be less effec-tive against the therapy-resistant flora such likeEnterococcus facecalis, Actinomycesand Candidathat are frequently isolated in persistent root canals 6) .This is because of dilution of calcium hydroxide astime passes or dentin buffering effects 7) . Therefore,alternative medicaments should be explored thatwould maximize microbial eradication when used asintracanal disinfection. Intracanal disinfection of infected root canal is one of important treatment procedure. This in vitrostudyaimed to evaluate whether the surface polymers of controlled release drug (CRD) can effectively control therelease rate of chlorhexidine for root canal disinfection. Four CRD prototypes were prepared: Group A(n=12); The core device (absorbent paper point) was loaded with 40% CHX solution as control. Group B(n=12); same as group A, but the device was coated with chitosa n. Group C (n=12); same as group Aand then coated three times with 5% PMMA. Group D (n=12); same as group A and then coated threetimes with 3% PLGA. All CRD prototypes were soaked in 3 mL dist illed water for experimental periodsand the concentrations of released CHX from each CRD prototype were determined using a UV spectropho-tometer. Results showed that release rate of CHX were the greatest in the non-coated group (controlgroup), followed by the chitosan-coated group, the PLGA-coated group, and the PMMA-coated group (P <0.05). This data indicate that surface polymers can control the release rate of CHX from the CRD proto-types.

Veno-venous bypass in liver transplantation: heparin-coated perfusion circuits reduce the activation of humoral defense systems in an in vitro model.

We studied the effects of bypass circuit surface heparinization on kallikrein-kinin, coagulation, fibrinolytic and complement activation in a closed model system for simulating veno-venous bypass (WBP) in orthotopic liver transplantation (OLT). The circuits were identical to those in routine use during clinical OLT in our institution. Fresh whole human blood diluted 1:2 with Ringer's acetate was circulated at a non-pulsatile flow (2 l/min) and at a constant temperature (37.5 degrees C) for 12 h. In 10 experiments, the entire inner surface of the circuits was coated with end-point attached heparin (HC). In the remaining 10, non-treated PVC tubing was used (NC). Components of the plasma kallikrein-kinin, coagulation, fibrinolytic and complement systems were analyzed using functional techniques (chromogenic peptide substrate assays) and enzyme immunoassays at baseline, 3 and 12 h. Significant activation of the initial (C3bc) and terminal (TCC) components of the complement system were found in both the NC and HC groups after 3 and 12 h: C3bc: NC: baseline = 4 (3.5-7.7), 3 h = 17.3* (12.5-27), 12h = 31* (17.7-63.6), HC: baseline = 4.9 (3.2-6.8), 3h = 9* (6-14.4), 12h = 13.7* (7.4-18.1). TCC: NC: baseline = 0.4 (0.2-0.6), 3h = 5*(0.8-11.9), 12 h: 13.1* (4.2-25.7). HC: baseline = 0.5 (0.1-0.6), 3 h = 0.6* (0.1-0.8), 12 h = 1.2* (0.3-2) AU/ml; median and range (*: p < 0.05). The C3bc and TCC concentrations were significantly higher in the NC group at 3 and 12 h, compared to the HC group: C3bc (NC vs. HC group): 3 h, p < 0.001; 12 h, p < 0.001. TCC (NC vs. HC group): 3h, p < 0.001; 12 h, p < 0.001. Significant increases in the values of thrombin-antithrombin complexes (p = 0.003), prothrombin fragment 1 + 2 (p = 0.006) and plasmin-alpha2-antiplasmin complexes (p = 0.016) were found in the non-coated group, but not in the heparin-coated group during the observation period, showing that the coagulation and fibrinolytic systems were activated in the non-coated circuits. We conclude that heparin-coating of the internal surface of the extracorporeal perfusion circuit used for WBP reduces activation of the plasma cascade systems in a closed venous system in vitro.

Release of Lipopolysaccharide Toxicity-Modulating Proteins in Patients Undergoing Cardiopulmonary Bypass Using Noncoated and Heparin-Coated Extracorporeal Circuits: A Clinical Pilot Study

Cardiopulmonary bypass (CPB) induces a generalized inflammatory response, including activation of leukocytes, contributing to postoperative morbidity. The inflammatory pathways leading to this systemic inflammatory response syndrome are considered identical to those involved in septic shock. Therefore, we studied the release of bactericidal/permeability-increasing protein (BPI), lipopolysaccharide binding protein (LBP), and soluble CD14 (sCD14)-all proteins that modulate the effects of lipopolysaccharide (LPS)-in patients undergoing CPB. In addition, the effect of heparin coating of the extracorporeal bypass circuit on the release of these parameters was assessed. Prospective, randomized clinical pilot study. Cardiothoracic Surgery Department in a university hospital. Fourteen patients undergoing elective coronary artery bypass grafting were included. Seven patients underwent CPB using a standard, noncoated extracorporeal circuit, and seven patients had CPB using a heparin-coated extracorporeal circuit (Duraflo II). Blood samples were taken after induction of anesthesia, just before aortic crossclamping, and 0, 0.5, 1.5, 3, 6, 12, and 24 h after declamping. CPB with a noncoated extracorporeal circuit induced a sharp increase in neutrophil-derived BPI, manifest directly after release of the aortic crossclamp, which was significantly attenuated using a heparin-coated system. Also, CPB induced a gradual increase of the acute-phase reactant LBP, which was identical in the noncoated and heparin-coated groups. Systemic release of sCD14 after crossclamp release was significantly higher in the noncoated group compared with the heparin-coated group, but did not rise above baseline levels. These data confirm that CPB-induced leukocyte activation is attenuated using a heparin-treated extracorporeal circuit and point to the possible role of LPS toxicity-modulating proteins in the systemic inflammatory response after bypass surgery.

Carmeda surface heparinization in neonatal ECMO systems: long-term experiments in a sheep model

The thromboresistance in three Carmeda (Stockholm, Sweden) heparin-coated neonatal ECMO systems with a runtime of 45, 56 and 96 hours, respectively, and three noncoated systems with a runtime of 12, 42 and 66 hours, respectively, were compared using a sheep model. The flow rate was 200 ml/min and the activated clotting time (ACT) was kept at approximately 120 seconds. At the end of the experiment, the heparin-coated systems only contained minimal clotting while the controls showed major clotting in the entire system. Fibrin monomers were not detected until after 24 hours in the heparin-coated group, but demonstrated within 60 minutes in the noncoated group. It is concluded that the Carmeda heparin coating has a thromboresistant effect, and may be used to reduce the need for systemic heparinization in ECMO treatment of neonates.

Phosphatidylcholine-coated chest tubes improve drainage after open heart operation

Occlusion of chest drainage tubes by thrombus is not uncommon after open heart operations. It has been suggested that by coating the tube with phosphatidvlcholine (PC), the most prominent phospholipid in the erythrocytes outer membrane, it may be possible to overcome the blood-material interaction responsible for thrombus formation. To test this hypothesis 102 patients (75 males; mean age, 57 ± 10 years) were randomly allocated to receive either PC-coated or noncoated 32F chest drainage tubes. Preoperative status, type and length of operation, and duration of drainage were similar in the two groups as was postoperative blood loss. Patients receiving PC-coated tubes, however, had less residual blood clot in the tube after removal (0.7 ± 0.1 versus 3.1 ± 0.3 g; p < 0.001), a reduced incidence of pericardial effusions (17,6% versus 41.2%; p < 0.01), fewer postoperative supraventricular arrhythmias (2 of 51 versus 10 of 51; p < 0.002), and a shorter hospital stay (8.4 ± 0.3 versus 9.7 ± 0,5 days; p < 0.05). Late cardiac tamponade developed in 2 patients in the noncoated group 6 and 10 days postoperatively, which requited reexploration. The data show that PC-coated chest drainage tubes are less susceptible to occlusion by thrombus and their use is associated with a significant reduction in postoperative morbidity.

Heparin-coated cardiopulmonary bypass circuits reduce blood cell trauma Experiments in the pig

Blood cell trauma and postoperative bleeding remain important problems in cardiopulmonary bypass (CPB). We compared heparin-coated with non-coated circuits in the pig. Twenty animals were perfused for 2 h at normothermia using membrane oxygenators (Bentley Bos 50). Two groups were studied. In the non-coated group (NC, n = 11) the CPB circuits used were without a heparin coating. This group had systemic heparinization of 400 IU/kg to maintain an ACT (activated clotting time) of over 400 s during CPB. In the coated group (C, n = 9), all surfaces exposed to blood in the CPB circuits were heparin-coated. This group had the heparin dose reduced to 25% (100 IU/kg) without further administration regardless of ACT. During CPB, group C displayed shorter ACT (per definition), higher platelet count, platelet adhesion and lower fibrinolysis and haemolysis (P less than 0.05) as compared to group NC. No thromboembolic events were detected during CPB. Three animals in group NC and 4 animals in group C were weaned from CPB and protaminized. Four hours postoperatively, the leucocyte consumption was two-fold greater and blood loss about four-fold greater in group NC as compared with group C (P less than 0.05). Perfusion with heparin-coated surfaces reduces blood cell trauma. The decreased postoperative blood loss observed in group C is probably explained by the reduced dosages of heparin and protamine.