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OR 26 Toxic effects of dentin bonding agent components on human macrophages
Journal of E n d o d o n t i c s • 2 5 5
Pol. 2 3 , No. 4, April 1 9 9 7 i
Effect of bleaching agents on dental amalgam in vitro: a histochemical study. I. Rotstein*, C. Mor, J. R. Arwaz. Faculty of Dental Medicine, Jerusalem, Israel. The effect of 10% carbamide peroxide or 10% hydrogen peroxide on the surface levels of mercury, silver, tin and copper of amalgam fillings was tested in vitro, using scartnixag electron microscopy and energy dispersive spectrometric microanalysis. Samples of amalgam were treated for 14 and 28 days with either 10% carbamide peroxide or 10% hydrogen peroxide solutions and compared to phosphate buffer controls. A significant increase in mercury levels occurred following treatment with carbamide peroxide for 14 days (p<0.01) a_rrd28 days (p<0.001) or hydrogen peroxide for 28 days (p<0.001). A significant increase in silver levels occurred following treatment with carbamide peroxide for 14 days (t9<0.05) and 28 days (p< 0.01) or hydrogen peroxide for 14 days (p<0.05) or 28 days (p< 0.001). A significant reduction in tin levels occurred following treatment with hydrogen peroxide for 14 days (p<0.01) and 28 days (p<0.001), or carbamide peroxide for 28 days (p<0.01). A significant reduction in copper levels was found only following treatment with carbamide peroxide for 14 days (p<0.05). It therefore appears that oroloneed treatment with ble0ching aeents may cause microstructural chances in amalgam surfaces, possibly increasing exoosure of patients to toxic byproducts.
ORORI
The depth of hemoglobin penetration into dentin. L. RICKS* and R.E. WALTON. University of Iowa, College of Dentistry, Iowa City, IA. It has been theorized that tooth discoloration after trauma is due to lysis of red blood cells (RBC's) which are distributed into tubules. Previous studies of tooth discoloration employed tooth submergence into hemolyzed red blood cells after canal preparation. Objective: To determine patterns of RBC's pigment penetration into dentin with intracanal placement following pulp extirpation and canal preparation. Study Design: 50 premolars were randomly assigned to experimental (40 teeth) and control (10 teeth) groups. Teeth were sectioned at mid-root. In the experimental teeth, 20 had pulp extirpation with broaches and 20 had canal preparation with NaOCL irrigation. All experimental chambers were filled with RBC's which were hemolyzed by centrifuge, then introduced into the chamber with a pipette. Control teeth had either pulp extirpation (5 teeth) or canal preparation (5 teeth) without RBC placement. All were placed into a humidor at 37°C for 24 hours then the RBC's placement was repeated. After 30 days of incubation, all teeth were fractured B-L and photographed at 16X magnification. Three evaluators (blinded) determined the pattern of pigment penetration into dentin. Inter-rater reliability was evaluated using Cohen's Kappa. Results: The discoloration (pigment penetration) extended to the CEJ/DEJ in most (93%) of the pulp extirpated and most (84%) of the canal-prepared premolars. Conclusions: Intra-chamber staining of premolars after pulpal extirpation or canal preparation was an effective method for discoloring teeth; most pigment extended to the DEJ and/or CEJ.
OOtRI A comparison of nickel titanium versus stainless steel spreaders in curved canals CC Shull*, RJ Loushine, and LAWest USA Dental Activity, Fort Gordon, Georgia The ability of an endodontic spreader to penetrate within one millimeter o f the prepared root canal enhances the sealing ability of gutta-percha. This study examines the differences in penetration depths of nickel titanium and stainless steel spreaders in curved canals fitted with gutta-percha master cones. Twenty-eight mesial and distal roots o f twenty-five extracted molars with curved canals of 20 to 30 degrees were instrumented, measured and fitted with gutta-percha master cones to working length. Size #30 nickel titanium and stainless steel spreaders were inserted into each canal and a controlled force o f 15 newtons was applied with an Instron. Spreader depths were compared using digital radiography measuring the distance from the tip spreader to the tip of the fitted master cone. Data were analyzed using the Student's t-test. The mean distance from the depth of penetration to working l~mgth for the nickel titanium and stainless steel spreaders was 1.5250 + 0.976 mm and 3.3417 + 0.886 mm, respectively. The difference is statistically significant at p< .001. The findings of this study suggest that nickel titanium snreaders consistently achieve deever penetration than the stainless steel spreaders.
Toxic Effects of Dentin Bonding Agent Components on Human Macrophages. D.R. Rakich*, I.C. Wataha, C.A. Lefebvre, R.N. Weller. School of Dentistry, Medical College of Georgia, Augusta, Georgia. Dental resins have been proposed as root-end filling materials. Previous studies have documented the release of dental resin components in vitro and in vivo, but the biological implications of this release are not clear. Since macrophages are likely to direct any inflammatory response to released components, the effect of these components on macrophage function is important. The purpose of this study was to determine the concentrations of components of dentin bonding agents (DBAs) that are toxic to human macrophages in vitro. Solutions of purified 4-META, Bis-GMA, and UDMA were prepared in ethanol and in water for HEMA. Human THP-1 macrophages were plated and incubated at 37"C and 5 % COz for 24 h. DBAs were added in 1.0 ~tL (EtOH) or 20 #L 0-120) aliquots and the cells were incubated for an additional 12-72 h (n = 8). Controls contained only ethanol or water. THP-1 mitoehrondrial activity was estimated using the MTI" assay. The 50% toxicity concentration 0"C-50) levels were determined from plots of concentration versus mitochondrial activity. As the time of exposure increased, mitoehondrial activity was increasingly suppressed. (ANOVA, Tukey, ¢~ = 0.05). The TC-50's Omol/L) at 24 h were ranked from least to most inhibitory: HEMA (10,000) < 4-META (7,500) < Bis-GMA (130) < UDMA (110). The ranking was similar for all exposure times. Resin comuonents adverselv affect the mitochondrial activity of human maerot)ha~,es, and the effect is time deoendent. This research was supported by the AAE Foundation and the MCG Bioeompatibility Program.
Pol. 2 3 , No. 4, April 1 9 9 7 i
Effect of bleaching agents on dental amalgam in vitro: a histochemical study. I. Rotstein*, C. Mor, J. R. Arwaz. Faculty of Dental Medicine, Jerusalem, Israel. The effect of 10% carbamide peroxide or 10% hydrogen peroxide on the surface levels of mercury, silver, tin and copper of amalgam fillings was tested in vitro, using scartnixag electron microscopy and energy dispersive spectrometric microanalysis. Samples of amalgam were treated for 14 and 28 days with either 10% carbamide peroxide or 10% hydrogen peroxide solutions and compared to phosphate buffer controls. A significant increase in mercury levels occurred following treatment with carbamide peroxide for 14 days (p<0.01) a_rrd28 days (p<0.001) or hydrogen peroxide for 28 days (p<0.001). A significant increase in silver levels occurred following treatment with carbamide peroxide for 14 days (t9<0.05) and 28 days (p< 0.01) or hydrogen peroxide for 14 days (p<0.05) or 28 days (p< 0.001). A significant reduction in tin levels occurred following treatment with hydrogen peroxide for 14 days (p<0.01) and 28 days (p<0.001), or carbamide peroxide for 28 days (p<0.01). A significant reduction in copper levels was found only following treatment with carbamide peroxide for 14 days (p<0.05). It therefore appears that oroloneed treatment with ble0ching aeents may cause microstructural chances in amalgam surfaces, possibly increasing exoosure of patients to toxic byproducts.
ORORI
The depth of hemoglobin penetration into dentin. L. RICKS* and R.E. WALTON. University of Iowa, College of Dentistry, Iowa City, IA. It has been theorized that tooth discoloration after trauma is due to lysis of red blood cells (RBC's) which are distributed into tubules. Previous studies of tooth discoloration employed tooth submergence into hemolyzed red blood cells after canal preparation. Objective: To determine patterns of RBC's pigment penetration into dentin with intracanal placement following pulp extirpation and canal preparation. Study Design: 50 premolars were randomly assigned to experimental (40 teeth) and control (10 teeth) groups. Teeth were sectioned at mid-root. In the experimental teeth, 20 had pulp extirpation with broaches and 20 had canal preparation with NaOCL irrigation. All experimental chambers were filled with RBC's which were hemolyzed by centrifuge, then introduced into the chamber with a pipette. Control teeth had either pulp extirpation (5 teeth) or canal preparation (5 teeth) without RBC placement. All were placed into a humidor at 37°C for 24 hours then the RBC's placement was repeated. After 30 days of incubation, all teeth were fractured B-L and photographed at 16X magnification. Three evaluators (blinded) determined the pattern of pigment penetration into dentin. Inter-rater reliability was evaluated using Cohen's Kappa. Results: The discoloration (pigment penetration) extended to the CEJ/DEJ in most (93%) of the pulp extirpated and most (84%) of the canal-prepared premolars. Conclusions: Intra-chamber staining of premolars after pulpal extirpation or canal preparation was an effective method for discoloring teeth; most pigment extended to the DEJ and/or CEJ.
OOtRI A comparison of nickel titanium versus stainless steel spreaders in curved canals CC Shull*, RJ Loushine, and LAWest USA Dental Activity, Fort Gordon, Georgia The ability of an endodontic spreader to penetrate within one millimeter o f the prepared root canal enhances the sealing ability of gutta-percha. This study examines the differences in penetration depths of nickel titanium and stainless steel spreaders in curved canals fitted with gutta-percha master cones. Twenty-eight mesial and distal roots o f twenty-five extracted molars with curved canals of 20 to 30 degrees were instrumented, measured and fitted with gutta-percha master cones to working length. Size #30 nickel titanium and stainless steel spreaders were inserted into each canal and a controlled force o f 15 newtons was applied with an Instron. Spreader depths were compared using digital radiography measuring the distance from the tip spreader to the tip of the fitted master cone. Data were analyzed using the Student's t-test. The mean distance from the depth of penetration to working l~mgth for the nickel titanium and stainless steel spreaders was 1.5250 + 0.976 mm and 3.3417 + 0.886 mm, respectively. The difference is statistically significant at p< .001. The findings of this study suggest that nickel titanium snreaders consistently achieve deever penetration than the stainless steel spreaders.
Toxic Effects of Dentin Bonding Agent Components on Human Macrophages. D.R. Rakich*, I.C. Wataha, C.A. Lefebvre, R.N. Weller. School of Dentistry, Medical College of Georgia, Augusta, Georgia. Dental resins have been proposed as root-end filling materials. Previous studies have documented the release of dental resin components in vitro and in vivo, but the biological implications of this release are not clear. Since macrophages are likely to direct any inflammatory response to released components, the effect of these components on macrophage function is important. The purpose of this study was to determine the concentrations of components of dentin bonding agents (DBAs) that are toxic to human macrophages in vitro. Solutions of purified 4-META, Bis-GMA, and UDMA were prepared in ethanol and in water for HEMA. Human THP-1 macrophages were plated and incubated at 37"C and 5 % COz for 24 h. DBAs were added in 1.0 ~tL (EtOH) or 20 #L 0-120) aliquots and the cells were incubated for an additional 12-72 h (n = 8). Controls contained only ethanol or water. THP-1 mitoehrondrial activity was estimated using the MTI" assay. The 50% toxicity concentration 0"C-50) levels were determined from plots of concentration versus mitochondrial activity. As the time of exposure increased, mitoehondrial activity was increasingly suppressed. (ANOVA, Tukey, ¢~ = 0.05). The TC-50's Omol/L) at 24 h were ranked from least to most inhibitory: HEMA (10,000) < 4-META (7,500) < Bis-GMA (130) < UDMA (110). The ranking was similar for all exposure times. Resin comuonents adverselv affect the mitochondrial activity of human maerot)ha~,es, and the effect is time deoendent. This research was supported by the AAE Foundation and the MCG Bioeompatibility Program.