IADR Abstract Archives

Effects of Hydrophilicity of Resins on Microtensile Bond Strengths

Objective: Hydrophilic resins bond very well to wet dentin but tend to absorb water and weaken dentin bonds over-time.  If hydrophobic resins could be coaxed into acid-etched dentin using dentin wet with ethanol instead of water, resin-dentin bonds may be more durable.  Purpose: To measure microtensile bond strengths (MTBS) of five experimental resins of increasing hydrophilicity bonded to human third molar dentin.  Methods: All five resins (see Ito et al., Biomaterials, 2005;26:6449-59 for composition) were solvated in 50 vol% ethanol and applied to dentin etched with 37% PA for 15 sec.  There were 3 different surfaces:  Group 1-dentin wet with water; Group 2-dentin wet with ethanol; Group 3-dentin dried for 30 sec.  After bonding, composite buildups were created and then the teeth were placed in water at 37°C for 24 hr.  They were then cut longitudinally into slabs and the slabs trimmed into hour-glass shapes 0.7 mm thick and 0.7 mm wide.  Results: Microtensile bond strengths (MPa) were:

Group/δh

Condition

Resin 1

6.4(J/cm3)½

Resin 2

8.4(J/cm3)½

Resin 3

9.9(J/cm3)½

Resin 4

10.6(J/cm3)½

Resin 5

10.7(J/cm3)½

1-wet H2O

5.4±2.9(6)a

5.4±2.7(10)a

24.6±6.0(16)b

15.7±7.1(16)b

46.7±17.4(16)c

2-wet EtOH

16.6±4.6(11)b

24.8±6.4(16)b

35.6±8.9(16)c

35.8±5.2(19)c

47.9±12.3(16)c

3-dry 30 s

2.6±1.2(4)a

1.9±0.8(4)a

13.4±7.4(11)b

11.9±5.6(16)b

13.6±6.9(9)b

Values are mean ± SD (n) MPa.  Hydrophilicity ranked by Hoy's δh(J/cm3)½.

Regression analysis of microtensile bond strength vs. δh values revealed highly significant correlations (Group 1, R2=0.71, p<0.005; Group 2, R2=0.94, p<0.01; Group 3, R2=0.77, p=0.05).  The next challenge is to see how durable the bonds are over-time.  Conclusions:  Wet bonding with ethanol improved bond strength of all experimental resins solvated in ethanol, compared to wet bonding with water or dry bonding.  Phase changes were seen in resins 1 and 2 when bonding to dentin wet with water but not wet with ethanol. Supported by R01 DE014911 from the NIDCR (P.I. D.Pashley).


AADR/CADR Annual Meeting
2006 AADR/CADR Annual Meeting (Orlando, Florida)
Orlando, Florida
2006
28
Dental Materials: I - Adhesion-Composite Bond Strength
  • Nishitani, Yoshihiro  ( Okayama University, Okayama, N/A, Japan )
  • Yoshiyama, Masahiro  ( Okayama University, Okayama, N/A, Japan )
  • Agee, Kelli  ( Medical College of Georgia, Augusta, GA, USA )
  • Brackett, William W.  ( Medical College of Georgia, Augusta, GA, USA )
  • Haisch, Larry D.  ( University of Nebraska Medical Center, Lincoln, NE, USA )
  • Tay, Franklin R.  ( Medical College of Georgia, Augusta, GA, USA )
  • Pashley, David H.  ( Medical College of Georgia, Augusta, GA, USA )
    • Oral Session
    Effect of Substrate on Dentin Bonding
    03/08/2006