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  • 1. Vesna Miletic 1,2 , Ario Santini 1 1 The University of Edinburgh, Edinburgh Postgraduate Dental Institute, United Kingdom 2 University of Belgrade, School of Dentistry, Serbia Effect of preparation and storage on adhesive monomer conversion
  • 2.
    • Studies investigating the degree of conversion (DC) of adhesives - samples prepared in a variety of ways
    • Substrates such as potassium-bromide pellet/crystal, acetate strips, glass slides or dentine discs
    • Light curing with or without the use of a Mylar strip covering
    • Variations in storage parameters such as time, temperature, humidity and media
    INTRODUCTION
  • 3.
    • To study the effect of preparation and storage conditions on the DC of
    • two adhesive systems using
    • micro-Raman spectroscopy.
    OBJECTIVE
  • 4.
    • Sample preparation:
      • Etch-and-rinse (Excite, Ivoclar Vivadent )
      • and self-etch adhesive (Clearfil 3S, Kuraray )
      • n=5
      • Glass slides vs. Dentine discs
      • Mylar strip covering vs. No Mylar strip covering
      • LED light (bluephase, Ivoclar Vivadent ) intensity 650 mW/cm 2 , 10 s curing time, 1 mm distance
    MATERIALS AND METHODS
  • 5.
    • Sample preparation:
      • Etch-and-rinse (Excite, Ivoclar Vivadent )
      • and self-etch adhesive (Clearfil 3S, Kuraray )
      • n=5
      • Glass slides vs. Dentine discs
      • Mylar strip covering vs. No Mylar strip covering
      • LED light (bluephase, Ivoclar Vivadent ) intensity 650 mW/cm 2 , 10 s curing time, 1 mm distance
    MATERIALS AND METHODS
  • 6.
    • Micro-Raman spectroscopy
    • (5 min post-curing, 3 random spectra per sample, top surface)
    MATERIALS AND METHODS DC=[1-Rcured / Runcured] x 100
  • 7.
    • Storage conditions:
      • Adhesives: Excite and Clearfil3S (n=5)
      • Glass slides / Dentine discs
      • Mylar strip covering
      • LED light (bluephase) intensity 650 mW/cm 2 , 10 s curing time, 1 mm distance
      • Micro-Raman spectroscopy 5 min post-curing and after storage
    MATERIALS AND METHODS
  • 8.
    • Storage conditions (24 hours)
      • Group I (22±2ºC and 45±3% humidity) -
      • light proof container, laboratory bench
      • Group II (37±1ºC and 90±2% humidity) -
      • light proof container with side openings, water bath with punched aluminum foil cover
      • Group III (distilled water at 37±1ºC) -
      • glass vial, 1 ml distilled water, covered water bath
      • Group IV (artificial saliva at 37±1ºC) -
      • glass vial, 1 ml artificial saliva, covered water bath
    MATERIALS AND METHODS
  • 9.
    • Statistics
      • ANOVA and repeated measures ANOVA
      • t test
      • significance level α =0.05
    MATERIALS AND METHODS
  • 10. RESULTS
  • 11.
      • Sample storage - Excite - Glass slides
      • Groups: high humidity, distilled water and artificial saliva => sample deformation, impossible to obtain micro-Raman spectra from the top surface
      • Group stored at 22±2ºC and 45±3% humidity
      • Before: DC=70.8%(1.7%)
      • After: DC=73.6%(1.8%)
      • [paired t-test, p<0.05]
    RESULTS
  • 12.
      • Sample storage - Clearfil 3S - Glass slides
    Group 1 Group 2
      • Group 1: p<0.001
      • Group 2: p<0.001
      • Group 1 vs. Group 2 (before): p=0.208
      • Group 1 vs. Group 2 (after): p<0.001
      • [t-test]
    RESULTS
  • 13.
      • Sample storage - Excite - Dentine discs
    Group 1 Group 2 Group 3 Group 4
      • Before vs. After
      • Group 1: p=0.002
      • Group 2: p=0.007
      • Group 3: p<0.001
      • Group 4: p<0.001
      • [repeated measures ANOVA and paired t test]
    RESULTS
  • 14.
      • Sample storage - Clearfil 3S - Dentine discs
      • Repeated measures ANOVA
      • Factor “Medium”: p=0.507
      • Factor “Time”: p<0.001
      • Interaction “Medium” x “Time”: p=0.190
    RESULTS
  • 15.
    • Sample preparation and storage significantly affected the DC of the etch-and-rinse and self-etch adhesive
    • Differences in the effect of both preparation and storage were observed for the two adhesives
    • Oxygen inhibition on the adhesive surface was significantly reduced using Mylar strips
    • “ Dark” cure during storage increased the initial DC due to consumption of C=C double bonds
    • Compared to storage in air, liquid media further increased the DC, most likely due to elution of monomers
    CONCLUSIONS
  • 16.
    • Variables such as oxygen inhibition and elution should be eliminated as they do not represent the DC of the adhesive polymer
    • Non-dental models may be appropriate for comparing e.g. effects of curing lights/curing times on conversion but not for material comparison since the results may not be clinically relevant
    CONCLUSIONS