Temporary Pacemaker Treatment in Open Heart Surgery: Pre- to Postoperative Changes in the Electrogram Characteristics

Thirty-three patients undergoing cardiac surgery in general hypothermia were investigated during temporary pacemaker treatment for changes in right ventricular electrogram amplitudes (AMAX, UMAX) and maximum derivatives (DMAX, SMAX) from pre- to postoperative phase (AMAX = amplitude of the part of the electrogram with highest mean maximum derivative (SMAX), DMAX = maximum derivative, UMAX = maximum amplitude deflection). Standard commercially available electrodes were used in 28 of the patients. A paired comparison (n=29) showed a fall in AMAX from 8.64 ± 0.91 mV (mean ± SEM) preoperatively to 4.94 ± 0.43 mV (p < 0.001) between the 4th and 6th postoperative day; UMAX dropped from 11.09 ± 0.95 mV preoperatively to 5.44 ± 0.42 mV (p < 0.000001) from the fourth to the sixth postoperative day. In the same period DMAX fell from 1.57 ± 0.13 V/s to 0.67 ± 0.05 V/s (p < 0.000001), and SMAX from 0.76 ± 0.06 V/s to 0.32 ± 0.02 V/s (p < 0.000001). The most marked fall in amplitudes and maximum derivatives occurred during the first 24 hours. A slight, but nonsignificant increase occurred in amplitudes and maximum derivatives from the 4th to 6th postoperative day until the electrodes were removed the 10th to 19th postoperative day. Amplitudes and maximum derivatives were of the same value in patients with aortic valve compared with coronary heart diseases in spite of a more deteriorated mypcardial function in the former group. The changes in amplitudes and maximum derivatives followed the same pattern in the two groups from the pre-to postoperative phase. This indicates that the additional local hyperthermia applied to the patients undergoing valve surgery was of no importance in the electrogram changes. Despite the fact that the electrogram maximum derivative and maximum amplitude needed to inhibit a temporary pulse generator are of a low magnitude, the values found were so small that they might provoke demand failure. This actually occurred in four patients.     

Comparative study of dentin adhesives

Abstract – The marginal adaptation of Silux after application of different dentin adhesives was investigated in dentin cavities prepared in extracted human teeth. The cavity diameter ranged from 1.8 to 6.4 mm and the cavosurface angle was 90°, 110°, 135° or 160°. The investigation included the following adhesives: Clearfil, Creation 1150, GLUMA, NPG-GMA + PMDM, Palfique, Panavia, Scotehbond and Superbond. Silux Enamel Bond was used as control. The most effective adhesive was GLUMA followed by Superbond and then NPG-GMA + PMDM; Palfique, Panavia and Scotehbond were all less effective than NPG-GMA + PMDM, and both Clearfil and Creation 1150 were inferior to the control, Silux Enamel Bond. None of the adhesives were able to prevent the formation of marginal gaps when measured 10 min after polymerization. After water absorption for 1 day, only GLUMA and Superbond produced gapfree fillings. Increasing the cavosurface angle resulted in a significant improvement of the effect of all adhesives, the main reason for this being the reduced ratio volume of filling to area of cavity wall.     

Adhesion to dentin by means of Gluma resin

Abstract – In its present version, the Gluma system for bonding restorative resin to dentin involves the application of an enamel bonding agent prior to the composite resin. Conceivably, pretreating the dentin with solutions of amino acids, and incorporating camphorquinone and selected methacrylic monomers into the Gluma adhesive would nullify the need for the enamel bonding agent. A bond strength to dentin of 13.4 MPa was obtained in the control experiment. Using a solution of pyruvic acid and glycine as pretreatment, and an optimized adhesive mixture containing glutaraldehyde, HEMA, BIS-GMA, camphorquinone, and water, bond strengths to dentin of 14.5 MPa and to enamel of 23.3 MPa were obtained. Thus, the new Gluma bonding system gave acceptable bond strengths without the prior application of enamel bonding agents.     

Surface discoloration of restorative resins in relation to surface softening and oral hygiene

Abstract — Restorative resins are susceptible to softening caused by organic acids produced in plaque. Consequently, plaque-covered resin restorations may be liable to pronounced surface staining. In the clinical part of the study a relationship between surface staining and local oral hygiene was demonstrated. This may be explained by the results from the laboratory part of the study, in which a relationship between surface staining and softening was found.     

CARBOHYDRATE-DEFICIENT TRANSFERRIN AS A MARKER OF ALCOHOL INTAKE: A STUDY WITH HEALTHY SUBJECTS

This paper reports the results of a 3-week drinking experimentin 51 healthy male subjects, examining the value of %CDT (carbohydrate-deficienttransferring in the context of different levels of alcohol intake.All healthy persons were urine-tested drug-free and underwentdaily breath alcohol tests for the 7 days preceding, and duringthe whole 3 weeks of, the experiment. Subjects were dividedinto five groups, consuming different amounts of alcohol dailyover a 3-h period in the presence of the investigators. Thefive groups consisted of 10, 9, 10, 16 and 6 subjects respectivelyand consumed a daily dose of ethanol of 20, 40, 60, 80 and 80g respectively for 3 weeks. No significant changes in %CDT weredetected in most subjects, even in the 80 g alcohol-consuminggroups. The results suggest that CDT is not sensitive for thedetection of short-term heavy drinking by healthy subjects.     

Impression materials: effect of hydrophilicity and viscosity on ability to displace water from dentin surfaces

Abstract – The water-displacing ability of hydrophilic and hydrophobic impression materials was determined and related to the hydrophilicity and viscosity of the materials. The waterdisplacing ability of the materials was determined on a network of grooves in a dentin surface covered by a drop of water. After setting of the material, the number of crossings reproduced in the impression was calculated in percent of the total number of crossings. The hydrophilicity was assessed by measuring the contact angle between water and impression material. To determine viscosity, a rotoviscosimeter was used. Impression materials with contact angles less than 70° showed a significant negative correlation between water-displacing ability and contact angle, i.e. the reproducing ability decreased with decreasing hydrophilicity of the materials. Impression materials with contact angles above 70° showed a significant positive correlation between water-displacing ability and viscosity, i.e. the water-displacing ability improved with increasing viscosity.     

Effect of disinfecting solutions on surface texture of alginate and elastomeric impressions

Abstract – The effect of immersion in six disinfecting solutions on the surface texture of 10 impression materials was investigated. Assessment of the surface texture was based on measurement of the ability to reproduce fine detail. Impressions were taken of a roughness standard, i.e. a steel block with known roughness. After setting, the impressions were either stored at room temperature for 24 h, for control, or immediately immersed in a disinfecting agent for 60 min (in one case 10 min), and after 24 h poured with gypsum. After another 24 h, the roughness of the dies was recorded with a profilometer. Three addition-curing silicones were left unaltered by disinfection. For the remaining seven materials, the ability of detail reproduction was changed for some of the combinations of impression material and disinfecting solution. In general, this meant a reduction of detail reproduction, but occasionally an improvement of the surface texture resulted from disinfection. Changes in surface texture were most often brought about by a solution of chlorinated trisodium phosphate. It was concluded that elastomeric impression materials reproduced fine detail better than did alginates and that both types of impression material may be immersed in specific disinfecting solutions for as long as 1 h without the surface texture being impaired.     

Marginal adaptation of resin in relation to application technique and use of a calcium hydroxide liner

Abstract – The marginal adaptation of a restorative resin was examined in cone-shaped cavities prepared in extracted human teeth. The use of a thin layer of a Ca(OH)₂ liner in the bottom of the cavities did not influence the wall-to-wall (wtw) polymerization contraction and it did not affect the gap-reducing efficacy of a dentin-bonding agent. The wtw contraction was markedly increased when the restorative resin was applied in two layers parallel to the free surface of the cavity; the reason for this is supposed to be that the ratio between the volume of the filling (V) and the area of the cavity wall (A) is increased for the second layer compared to the V/A ratio found in cavities filled with one increment.     

Mechanical properties of heat treated restorative resins for use in the inlay/onlay technique

Abstract – Inlay/onlay materials based on composite resins have recently been introduced. It was the aim of the present study to investigate the effect of post-curing temperature on selected mechanical properties. Four different composite resins were produced. The composite resins had identical filler content, but varied with respect to the content of the monomers BISGMA, TEGDMA, UEDMA, and HEMA. After Initial curing by light, the materials were post-cured at 37, 100, 125, 150, 175, or 200°C for 1 h. We then measured diametral tensile strength, flexural strength, and modulus of elasticity. These properties were found to vary with the composition of the material. Composites containing UEDMA or UEDMA/HEMA were stronger and stiffer than BISGMA/TEGDMA formulations. The optimum post-curing temperature was 150°C, but the increase in strength and stiffness was moderate, only about 9%.     

The Many Faces of Goodpasture's Syndrome

ABSTRACT Four cases of antiglomerular basement membrane (antiGBM) antibody mediated disease with unusual features are presented. Lung involvement was absent in one patient whereas the other 3 had Goodpasture's syndrome. Recognition of the nature of the disease was delayed in all cases, due to occurrence during pregnancy in one case and due to the indolent course of the renal injury in the other 3 cases. The therapeutic approach to these variant forms of antiGBM antibody mediated disease is discussed.