In vivo evaluation of the biocompatibility of three current bonding agents.

The aim of this in vivo study was to evaluate the biocompatibility of three current bonding agents and calcium hydroxide cement. Sixty polyethylene tubes filled with the following materials: Group 1: Prime & Bond NT (PB-Dentsply, US; Group 2: Bond 1 (BO-Jeneric/Pentron, US); Group 3: Optibond Solo (OP-Kerr, US); and Group 4 (control): calcium hydroxide cement - Dycal (CH-Dentsply, US) were implanted into the connective tissue of 30 rats. After 15, 30 and 60 days, the implants were excised and the animals sacrificed. The biopsies were immersed in Karnovsky (pH, 7.2) fixative solution for 48 hours, and processed using routine histological technique. Six-micron-thick sections were cut and stained with hematoxilin and eosin and Masson's trichome technique. Microscopic evaluation was used to compare the connective tissue reactions caused by the experimental and control materials adjacent to the tube opening. At 15 days, the experimental and control materials triggered a moderate to intense inflammatory response which gave rise to a thick capsule adjacent to the tube opening. With time, the inflammatory reaction decreased. At 60 days, the connective tissue adjacent to the bonding agents exhibited a persistent inflammatory response mediated by macrophages and giant cells which were engulfing displaced resin components. On the other hand, for the control group (calcium hydroxide) no inflammatory response associated with a thin capsule adjacent to the material was observed even at the 30-day period. The hard-setting calcium hydroxide cement allowed complete healing and was considered more biocompatible than the bonding agents.

Vitreous humour as a complementary sample to blood for the detection/confirmation of diazepam: ante-mortem and post-mortem studies in an animal model.

The quantification of medical or toxic substances in vitreous humour (VH) could be very useful in forensic toxicology when blood sample determinations are impossible due to absence or deterioration. However, few studies have been made in this area and even fewer have tried to find a relationship between drug levels in both samples. To determine a correlation ratio between blood and VH diazepam (DZ) levels, we performed an experimental study using rabbits administered with a sub-toxic dose of DZ under known and controlled conditions. Blood and VH samples were collected 0.5, 1, 2, 3 and 6 hours after the drug administration in order to determine DZ and its main active metabolite, desmethyldiazepam (DMD). In addition, we have studied an animal group sacrificed 2 hours after intramuscular (i.m.) drug administration with blood and VH collection 24 hours later, to evaluate the existence of possible post-mortem changes. After DZ administration, a fast absorption phase was observed with a plasma Cmax value 1 hour after, followed by a rapid concentration decrease, with a half-life of 1 hour, indicating that, besides elimination, a fast distribution to other organs and tissues and/or hepatic metabolism occurred. Diazepam Cmax value in VH was achieved between 1 and 2 hours, when plasma concentrations had already decreased to half the value. The plasma/VH DZ ratio calculated at this time was 10. In the post-mortem study, while plasma DZ concentration at 24 hours was smaller, DMD levels were higher than those at the time of death. In the VH, both DZ and DMD concentrations at 24 hours were higher than those obtained at the time of death. That is, in both fluids DZ and DMD concentrations were different from those at the time of death and post-mortem distribution and redistribution phenomena occurred. The combination of ante-mortem and post-mortem studies has allowed the determination of a correlation ratio for DZ in the rabbit of 6 x, comparing the concentrations in VH collected 24 hours after death with the concentrations detected in plasma at the time of death. This study opens new perspectives for the use of VH as a complementary sample to blood for DZ detection and confirmation. The putative relevance of the correlation ratio obtained, for forensic toxicology practice with medical substances, namely benzodiazepines, recommends further studies in humans.

Circadian and seasonal variation of endogenous ubiquinone plasma level.

Coenzyme Q10 (CoQ10) or ubiquinone, a redox component of the mitochondrial electron transport chains, is a powerful antioxidant and membrane stabilizer that may prevent cellular damage during myocardial ischemia and reperfusion therapy. Coenzyme Q10 has been used primarily as an adjuvant therapy for some cardiomyopathies. However, one of the main problems in CoQ10 administration is the high variability of endogenous plasma and tissue levels, which seems to be dependent on several factors. This work explores temporal 24h and seasonal variation as well as gender and racial differences in endogenous plasma ubiquinone concentration. Coenzyme Q10 measurements (quantified by HPLC-UV) of 16 healthy volunteers were done during the daytime hours of activity beginning at 09:00h one day and ending at 09:00h the next day (13 different determinations) in two distinct months. April and October, of the year. A statistically significant circadian rhythm in plasma ubiquinone concentration that includes only the fundamental 24h component was demonstrated both in the April and October data. Furthermore, the time-point means of the ubiquinone concentration in the October study were invariably higher than those obtained in the April study. No statistically significant differences were found in CoQ10 concentration between male and female subjects, both in April and in October. In addition, racial differences were demonstrated; lower plasma ubiquinone levels were found in Caucasian compared to African subjects. However, the latter small group of subjects failed to demonstrate a circadian rhythm, neither in the April nor in the October analysis.

Response of human pulps capped with a self-etching adhesive system.

OBJECTIVE: The aim of this study was to evaluate the human pulp response following direct pulp capping with a current self-etching bonding agent and calcium hydroxide (CH). METHODS: Thirty-three sound human premolars had their pulp tissue mechanically exposed. Sterile distilled water was used to control the hemorrhage and exudation from the pulp exposure site. The pulps were capped with Clearfil Liner Bond 2 (CLB-2) or CH and the cavities were filled with a resin composite (Z-100) according to the manufacturer's instructions. After 5, 30 and 120-300 days, the teeth were extracted and processed for microscopic examination. RESULTS: At short-term, CLB-2 elicited a mild to moderate inflammatory pulp response with dilated and congested blood vessels adjacent to pulp exposure site. With time, macrophages and giant cells engulfing globules and particulates of resinous material displaced into the pulp space were observed. This chronic inflammatory pulp response triggered by fragments of bonding agent displaced into the pulp space did not allow pulp repair interfering with the dentin bridging. On the other hand, pulps capped with CH exhibited an initial organization of elongated pulp cells underneath the coagulation necrosis. Pulp repair and complete dentin bridge formation was observed at long-term evaluation. SIGNIFICANCE: The present study demonstrated that CH remains the pulp capping agent of choice for mechanically exposed human pulps. CLB-2 did not allow complete connective tissue repair adjacent to the pulp exposure site. Consequently, this bonding agent cannot be recommended for pulp therapy of sound human teeth.

Platelet activation is increased in cyclosporin A-induced hypertensive rats.

One of the most severe side effects of the immunosuppressive agent, cyclosporin A (CsA), is increased risk of thromboembolic complications and drug-related hypertension. Because platelets might be involved in these processes, we tested the possibility of CsA affecting platelet activation, which might contribute to these adverse drug reactions. The experiments were done using Wistar rats, treated or not (control) with CsA (Sandimmun Neoral), 5 and 30 mg/kg/day, for 7 weeks. Systolic, diastolic, and mean blood pressures, intracellular free calcium concentration ([Ca2+]i), platelet serotonin (5-HT) contents, and aggregation were determined, at weeks 0, 2, and 7 of treatment. Inositol phosphates (InsP) production, platelet thromboxane A2 (TXA2) generation, and morphology of platelets, through electron microscopy studies, also were compared. It was demonstrated that blood pressures increased in the CsA-treated groups, when compared with the control group, after 2 and 7 weeks of administration. CsA at both "attack" and "maintenance" doses increased basal, 5-HT, and thrombin-evoked [Ca2+]i after 2 and 7 weeks versus the control group. However, basal and evoked InsP production was stimulated by 5 mg/kg of CsA, but inhibited by 30 mg/kg, when compared with the control. Platelet 5-HT contents decreased significantly after 2 and 7 weeks in the CsA-treated groups, when compared with the control group. Collagen-induced whole blood platelet aggregation increased drastically in the "attack" CsA-treated group, whereas adenosine diphosphate (ADP)-induced platelet aggregation did not reach statistical significance. Finally, in vitro basal, collagen-, and ADP-evoked platelet TXA2 generation increased in both CsA concentrations, versus the control. In conclusion, our study demonstrates that both CsA doses alter platelet calcium homeostasis (even affecting the calcium fluxes differently), 5-HT and TXA2 contents and aggregation, which might contribute to the development and/or maintenance of high blood pressures and increased risk of thromboembolic complications.

Biocompatibility of two current adhesive resins.

The purpose of the study was to evaluate the biocompatibility of two current adhesive resins and a calcium hydroxide cement. Fifty-four polyethylene tubes were filled with these dental materials, which were hand-mixed or light-cured according to the manufacturer's directions: group 1--Clearfill Liner Bond 2 (Kuraray); group 2--Single Bond (3 M); and group 3--calcium hydroxide cement (Dycal-Dentsply). The materials were implanted into dorsal connective tissue of rats, which were killed 7, 30, and 60 days after the implantation procedure. The implant sites were excised, immersed in buffered Karnovsky's fixative, and processed using routine histological techniques. Sections of 6 microns thickness were stained with hematoxylin and eosin and assessed under light microscopy. Both adhesive resins at 7 days elicited a moderate/intense inflammatory reaction that decreased over time. Fibrous capsules surrounding the tubes were observed at 30 days. Half of the samples in groups 1 and 2 showed thin fibrous capsule formation containing macrophages, capillaries, lymphocytes, fibroblasts, and collagen fibers. Connective tissue healing was observed even though many specimens exhibited a persistent inflammatory reaction mediated by macrophages and giant cells at the 60-day evaluation. Dycal allowed complete healing at 30 days with only a thin fibrous capsule. In conclusion, all experimental materials were successfully walled off by the connective tissue of the rat. However the adhesive resins may release particulates that may, in turn, induce a persistent local inflammatory reaction. Consequently, in this specific condition, these materials cannot be regarded as biocompatible. Dycal was less irritating than the adhesive resins and was better tolerated by the connective tissue.

Biocompatibility of a resin-modified glass-ionomer cement applied as pulp capping in human teeth.

PURPOSE: to evaluate the human pulp response following pulp capping with calcium hydroxide (CH, Group 1), and the resin-modified glass-ionomer Vitrebond (VIT, Group 2). MATERIALS AND METHODS: Intact teeth with no cavity preparation were used as control Group (ICG, Group 3). Buccal Class V cavities were prepared in 34 sound human premolars. After exposing the pulps, the pulp capping materials were applied and the cavities were filled using Clearfil Liner Bond 2 bonding agent and Z100 resin-based composite. The teeth were extracted after 5, 30, and from 120 to 300 days, fixed in 10% buffered formalin solution, and prepared according to routine histological techniques. 6-microm sections were stained with hematoxylin and eosin, Masson's trichrome, or Brown & Brenn technique for bacterial observation. RESULTS: At 5 days, CH caused a large zone of coagulation necrosis. The mononuclear inflammatory reaction underneath the necrotic zone was slight to moderate. VIT caused a moderate to intense inflammatory pulp response with a large necrotic zone. A number of congested venules associated with plasma extravasation and neutrophilic infiltration was observed. Over time, only CH allowed pulp repair and complete dentin bridging around the pulp exposure site. VIT components displaced into the pulp tissue triggered a persistent inflammatory reaction which appeared to be associated with a lack of dentin bridge formation. After 30 days a few histological sections showed a number of bacteria on the lateral dentin walls. In these samples the pulp response was similar to those samples with no microleakage. VIT was more irritating to pulp tissue than CH, which allowed pulp repair associated with dentin bridge formation. These results suggested that VIT is not an appropriate dental material to be used in direct pulp capping for mechanically exposed human pulps.

Biocompatibility of an adhesive system and 2-hydroxyethylmethacrylate.

The aim of the study was to evaluate the biocompatibility of an adhesive system and a resin component when implanted into connective tissue of rats. Forty sponges embedded in both materials: Scotchbond MP (SBMP/ 3M-Group A) and 2-hydroxyethylmethacrylate (HEMA-Group B), were implanted into dorsal connective tissue of 20 animals. After 7, 15, 30, or 60 days of the implantation, the animals were sacrificed; implant sites were excised and immersed for 24 hours in Kamovisky's fixative. The samples were processed under routine histologic technique, being stained with H & E. Histological evaluation showed that both materials promoted at 7 days intense inflammatory response with predominance of neutrophils and macrophages. The intense connective reaction was replaced for fibroblastic proliferation associated with macrophages and foreign body giant cells over time. The persistent moderate inflammatory reaction adjacent to scattered fragments of materials was greater to HEMA than to the SBMP. Both experimental materials did not show acceptable biocompatibility with connective tissue of rats in spite of allowing an evident connective tissue healing.