Effects of de- and remineralization of dentin on bond strengths yielded by one-, three-, and four-step adhesives.
OBJECTIVE
To assess the effect of different peri- and intertubular dentin mineralization conditions and etching on shear bond strength in vitro.


METHODS
One hundred fifty crowns of extracted bovine incisors were embedded in resin and ground to expose the buccal coronal dentin. Sixty specimens were subjected to a demineralizing solution (DS) and another 60 teeth to a bacterial-based laboratory caries model (S. mutans, SM). Thirty specimens of each demineralization protocol (DS and SM) were randomly selected and remineralized (-R). Thirty sound dentin specimens served as control (C). Resin composite buildups (Tetric) were bonded after application of one of the following adhesives: a one-step self-etching adhesive (Xeno III), and a self-etching adhesive (Syntac Classic) without (three-step) and with prior additional 35% phosphoric acid etching (etch-and-rinse, four-step). Teeth were subjected to shear bond strength testing in a universal testing device at a crosshead speed of 0.5 mm/min (Ultradent method).


RESULTS
Bond strength value for group C ranged from 6.3 to 8.4 MPa (p > 0.05). DS and DS-R samples showed in creased bond strength with the one-step adhesive (11.6 MPa, p < 0.05), whereas the three-step adhesive with additional etching showed decreased bond strength (3.2 MPa, p < 0.05). SM samples showed the lowest bond strength of all adhesive systems (range 1.1 to 1.5 MPa, p > 0.05). Remineralization showed no effect on the latter group.


CONCLUSIONS
The degree of mineralization of the dentin is important for adhesion. Additional etching with phosphori acid reduced bond strength of a three-step adhesive.
Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental and Oral Medicine, University of Zürich, Switzerland. patrick.schmidlin@zzmk.unizh.ch
Patrick R
PR
Schmidlin
Jacqueline
J
Siebenmann
Peter
P
Kocher
Rainer
R
Seemann
Thomas
T
Attin
Andreas
A
Bindl
D000134:Acid Etching, Dental; D000818:Animals; D002417:Cattle; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003731:Dental Caries / Q000382:microbiology / Q000473:pathology; D003764:Dental Materials / Q000737:chemistry; D003793:Dental Restoration, Permanent; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry* / Q000145:classification; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011897:Random Allocation; D019279:Resin Cements / Q000737:chemistry; D033081:Shear Strength; D013295:Streptococcus mutans / Q000502:physiology; D013314:Stress, Mechanical; D017001:Tooth Demineralization / Q000382:microbiology / Q000473:pathology*; D014089:Tooth Remineralization
D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C078484:Syntac dentine adhesive; C090969:Tetric; C487957:Xeno III