Effect of calcium removal on dentin bond strengths.
OBJECTIVE
The purpose of this in vitro study was to determine the microtensile bond strengths (mu TBS) of 3 dental adhesives when applied to dentin decalcified with ethylenediaminetetraacetic acid (EDTA). The null hypothesis tested was that the removal of calcium from dentin would not influence the bond strengths.


METHODS
Eighteen extracted human molars were cut in 2 equal halves. One half served as the control, having no EDTA treatment, while the other half was assigned to 1 of 3 periods (1 hour, 24 hours, or 100 hours) of decalcification with buffered 0.5 mol/L EDTA. Middle dentin was bonded with 1 of 3 dentin adhesive groups: a self-etching primer, Clearfil SE Bond (SE); an acetone-based total-etch adhesive, Prime&Bond NT (NT); and an ethanol- and water-based total-etch adhesive, Single Bond (SB). The specimens were restored with Z-250 resin composite and sectioned in 0.9 +/- 0.2 mm2 sticks that were tested in tensile mode.


RESULTS
For each adhesive, the control group (not decalcified) resulted in statistically higher bond strengths than the treatment groups. For specimens that were not decalcified, SE and SB had statistically similar bond strengths, but both resulted in statistically higher bond strengths than NT. For specimens decalcified for 1 hour, SE resulted in statistically higher bond strengths than either SB or NT, which were ranked in the same statistical group. SE was the only dentin adhesive to result in measurable mu TBS after decalcification with EDTA for 24 hours, while SB/24 hour and NT/24 hour specimens debonded spontaneously prior to testing. All the specimens treated with EDTA for 100 hours debonded prior to testing.


CONCLUSIONS
Three conclusions were drawn: (1) All 3 adhesive systems included in this project bonded significantly better to calcified than to decalcified dentin, regardless of their composition; (2) The self-etching primer-based adhesive ranked consistently equal to or better than the 2 total-etch-based adhesives, regardless of the EDTA decalcification time; and (3) Removal of calcium may be more detrimental for adhesives that rely on dentin acid etching than for adhesives based on self-etching primers.
Perdigão
J
J
Division of Operative Dentistry, Department of Restorative Sciences, University of Minnesota, Minneapolis, Minnesota, USA. perdi001@tc.umn.edu
Eiriksson
S
S
Rosa
B T
BT
Lopes
M
M
Gomes
G
G
D000096:Acetone / Q000737:chemistry; D000134:Acid Etching, Dental / Q000379:methods; D000268:Adhesiveness; D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002118:Calcium / Q000737:chemistry*; D002614:Chelating Agents / Q000494:pharmacology; D003188:Composite Resins / Q000737:chemistry; D016001:Confidence Intervals; D003648:Decalcification Technique; D001840:Dental Bonding; D003804:Dentin / Q000187:drug effects / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000494:pharmacology; D000431:Ethanol / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008963:Molar; D011109:Polymethacrylic Acids / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry
D002614:Chelating Agents; C438313:Clearfil SE Bond; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT; D019279:Resin Cements; D012997:Solvents; C115612:single bond; D014867:Water; D000096:Acetone; D000431:Ethanol; D017438:Bisphenol A-Glycidyl Methacrylate; D004492:Edetic Acid; D002118:Calcium