Effect of deproteinization before and after acid etching on the surface roughness of immature permanent enamel.

OBJECTIVE: The purpose of this in vitro investigation was to assess the effect of deproteinization before and after acid etching on the surface roughness of immature human enamel of permanent teeth compared to acid etching alone using noncontact three-dimensional (3D) optical profilometer. MATERIALS AND METHODS: Forty-eight enamel blocks were randomly distributed into 4 groups (12 each) according to the surface treatment in the form of deproteinized with 2.5% sodium hypochlorite (NaOCl) before and after acid etching with 32% phosphoric acid (H3PO4) compared to application of H3PO4 alone. The surface roughness (Sa) was measured using a 3D optical noncontact surface profiler. Two specimens from each group were selected and prepared for scanning electron microscopic (SEM) analysis. Shapiro-Wilk test, one-way analysis of variance, and Tukey's honest significance difference test were used. All statistical analyses were established with a significance level of P < 0.05. RESULTS: The highest surface roughness (Sa) was recorded for Group 3/NaOCl ± H3PO4 and the lowest Sa was recorded for Group 1 (control). All surface treatments applied showed significantly greater values of surface roughness (Sa) than the enamel surfaces with no surface treatment (control). There was significant difference between control group and Group 2/H3PO4 (P = 0.002), Group 3/NaOCl ± H3PO4 (P = 0.0001), and Group 4/H3PO4 ± NaOCl (P = 0.017). There was no significant difference between Group 2/H3PO4 and Group 4/H3PO4 ± NaOCl. SEM evaluation showed different topographical features of deproteinized enamel surface. CONCLUSIONS: Deproteinizing the enamel of immature permanent teeth with 2.5% NaOCl before and after acid etching with 32% H3PO4 increased surface roughness compared to the application of H3PO4 alone.

Effect of whitening toothpastes on bonding of restorative materials to enamel of primary teeth.

OBJECTIVE: The aim of this in vitro investigation was to measure shear bond strength (SBS) of a resin composite and a resin-modified glass ionomer to enamel of primary teeth after application of different whitening toothpastes (WTs). MATERIALS AND METHODS: Eighty labial enamel surfaces of primary incisors were randomly distributed into 8 groups of 10 each according to the surface treatment and bonding material. G1 and G2, control (brushed with water without WT); G3 and G4, (brushed with Colgate Optic White WT [Colgate-Palmolive Company, New York, NY, USA]), G5 and G6, (brushed with Crest Pro-Health Whitening WT [Procter and Gamble, Cincinnati, OH, USA]) and G7 and G8, (brushed with Arm and Hammer Advance White Extreme Whitening with Stain Defense WT [Church and Dwight Co., Princeton, NJ, USA]). SBS was measured at a crosshead speed of 0.5 mm/min and the type of bond failure was assessed using a stereomicroscope. RESULTS: There was significant difference between SBS of composite resin in groups 1, 3, 5, and 7 (P < 0.001), but no difference between resin-modified glass ionomer in groups 2, 4, 6, and 8 (P < 0.056). SBS of group 1 (control) was greater than groups 3, 5, and 7. There was a significant difference between group 1 and group 2 as well as group 7 and group 8 (P < 0.001). CONCLUSIONS: WTs affect SBS of resin composite, but not resin-modified glass ionomer to enamel of primary teeth. No difference of failure modes between different groups of tested materials.