45S5 bioactive glass air-abrasion prior to composite resin cementation in hypomineralized dentin

This in vitro study aimed to evaluate the influence of air-abrasion with Bioglass 45S5 ( Bioactive Glass , BAG) on Knoop microhardness (HK) and shear bond strength (SBS) in sound dentin (D) and dentin with induced hypomineralization (HD). Dentin blocks were randomized and treated according to the experimental groups (n = 60): sound dentin (D), BAG air-abrasion in sound dentin (D-BAG), dentin with induced hypomineralization (HD), and BAG air-abrasion in HD (HD-BAG). HK and dentin surface characteristics were evaluated by scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDS) at baseline in D (T0), after hypomineralization induction (HD) (T1), and after air-abrasion (T2; D-BAG and HD-BAG). The air-abrasion protocol consisted of three air-abrasion sessions (once a week) for 1 min at 90° with BAG. For the SBS test, blocks of nanoparticle composite resin were made and bonded to dentin surfaces using Set PP cement (SDI). The specimens were stored for 1 week at 37 °C before SBS testing. The failure mode and dentin surface were evaluated using a stereomicroscope, SEM and EDS. Data were analyzed using one-way ANOVA and post-hoc Tukey (p < 0.05). HK values decreased from T0 (D) to T1 (HD), and increased from T1 (HD) to T2 (HD-BAG) (p < 0.05). SBS was highest for D and D-BAG and lowest for HD; however, HD-BAG showed no difference between the groups. SEM/EDS analyses revealed calcium- and phosphorus-rich precipitates on BAG-treated dentin surfaces. Air-abrasion with BAG increases the HK of HD and promotes SBS similar to sound dentin. • Air - abrasion with 45S5 bioglass (BAG) increased the microhardness of hypomineralized dentin. • BAG pretreatment did not affect the SBS of sound dentin and preserved the adhesive performance in hypomineralized dentin. • BAG-treated hypomineralized dentin showed increased calcium and phosphorus deposition. • BAG air - abrasion and Set PP cement formed a trabecular-like dentin layer after SBS.