Long-term microtensile bond strength of self-etch adhesives and influence of 7-s phosphoric acid etching on adhesion of a 3-step etch-and-rinse adhesive to the dentine of primary teeth.

BACKGROUND

The immediate microtensile bond strength (µTBS) of self-etch (SE) adhesives to primary dentine is promising, but evidence about the durability is scarce.

AIM

To assess the long-term µTBS of SE adhesives to primary dentine and to examine the effect of 7-s etching on µTBS of a 3-step etch-and-rinse (ER) adhesive.

DESIGN

The enamel of 115 caries-free human primary teeth was ground flat, and bonding was performed according to group assignment: G-aenial™ Bond/GC [GB], Clearfil™ SE Bond/Kuraray [CS], OptiBond™ XTR/Kerr [OX], Scotchbond™ Universal/3M™ [SU], Prime&Bond NT™/Dentsply [PB], and OptiBond™ FL/Kerr [OF]. After storage (24 h, 6 mos., 12 mos.), 1,762 beams were cut for µTBS testing. Fracture analysis was performed using light/fluorescence microscopy. Resin-dentine interfaces were exemplarily analyzed using SEM.

RESULTS

After 24 h, OX and SU showed significantly higher estimated mean µTBS than GB, which exhibited the lowest µTBS at all stages (p < .05). μTBS within each adhesive group showed slight variations over time (p > .05). OF_SE produced acceptable µTBS. Etching increased the mean immediate µTBS for OF (p > .05) and the percentage of cohesive fractures.

CONCLUSIONS

SE adhesives achieved durable μTBS to primary dentine. 7-s etching may improve the immediate µTBS of a 3-step ER adhesive.