The Effect of Aging and Thermocycling on Adhesive Bonding to Fluorosed Enamel

Abstract

Background Adhesive bonding to tooth surfaces could be affected by aging and structural abnormalities of tooth tissues. This study evaluated the shear bond strength of 2 contemporary adhesives to fluorosed tooth enamel following wet aging and thermocycling. Materials and Methods Two groups (n=40 each) of extracted premolars were respectively selected with mild and mod- erate fluorosis. Another 40 premolars with no fluorosis served as control. Cylinders of nano- filled composite were bonded in two subgroups onto buccal enamel of all teeth using AdperTM Single Bond 2 (ASB) and Adper Prompt L-Pop (ALP) adhesive systems (n= 20 each). Before testing the shear bond strength of all groups, 10 specimens from each of their subgroups were subjected to 6 months of wet aging in distilled water at 37±1oC and thermocycling at 5, 37 and 60oC with 30s dwelling time for 5000 cycles (Class 1). The other 10 were tested after 24h of wet storage with no thermocycling (Class 2). Both one-way ANOVA and Tukey’s comparisons ( =0.05) were then used to statistically analyze the collected data. The fracture surfaces of all specimens were also inspected to determine the common mode of bond failure. Results No differences were detected between bonding values of both adhesives to normal and fluo- rosed enamel (P>0.05). Wet aging and thermo- cycling has no effect (P>0.05) on the bonding values. The reported bond failures were mainly belonged to admixed and adhesive modes. Conclusion Both ASB and ALP adhesives provide compa- rable bonding values to normal and fluorosed tooth enamel. Wet aging and thermocycling have no adverse effect on the adhesive bond- ing to tooth enamel with different degrees of fluorosis. Keywords Adhesive bonding, aging, enamel, fluorosis, thermocycling.