Microtensile bond strength of 4 dentin adhesives to primary dentin

This study's purpose was to evaluate the aging effect on the bond strength of 4 adhesive systems on primary dentin 24 hours and 6 months after bonding.

The crowns of extracted, caries-free primary molars were grounded and flat surfaces were prepared and distributed into 4 groups (n=7-9). The adhesives Scotchbond Multi-purpose (SMP), Single Bond (SB), Clearfil SE Bond (CSB), and Adper Prompt L-Pop (APL) were applied with the composite resin Filtek Z-250. Specimens were stored in distilled water (37°C/24h), the crowns were sectioned, and 0.8-mm² resin-dentin sticks were obtained and divided into 2 groups: (1) 24h; and (2) 6m. Each group's specimens were tested under tensile at 0.5 mm/minute until they fractured. The fractured sticks were examined by scanning electron microscopy. The data were analyzed by 2-way repeated measures: analysis of variance; Tukey's test (P<.05); and Kruskal-Wallis test (P<.05).

The mTBS (MPa) means values were: SMP=33.28 (2.05), SB=23.27 (4.78), APL=20.64 (10.66), and CSB=18.94 (11.94) for the 24-hour group; and SMP=30.59 (6.29), SB=22.39 (5.9), CSB=21.50 (10.67), and APL=17.19 (6.88) for the 6-month group. The most frequent fracture type found was cohesive failure of the adhesive and mixed, with no statistically significant difference found between the groups.

Resin bond strength on primary dentin was not influenced by aging for the adhesive systems tested.