[Show abstract][Hide abstract] ABSTRACT: To assess the effects of three different dental adhesive systems on the formation of secondary root caries, in vitro, with a standardized interfacial gap in a filled cavity model.
40 sound human molars were selected and randomly assigned to four experimental groups: Clearfil SE Bond (CSEB), Xeno III (X-III), Scotchbond Multi-Purpose Plus (SBMP) and negative control (NC) without an adhesive system. After the standardized Class V cavity preparations on the buccal and lingual surfaces, restorations were placed with resin composite (Filtek Z250) using a standardized interfacial gap, using a 3 x 2 mm piece of 50 microm metal matrix. The teeth were sterilized with gamma irradiation and exposed to a cariogenic challenge using a bacterial system with Streptococcus mutans. Depth and extension of wall lesions formed and the depth of outer lesions were measured by software coupled with light microscopy.
For wall lesion extension the ANOVA test showed differences between groups except between X-III and SBMP (P=0.294). The Tukey's test of confidence intervals indicated smaller values for the CSEB group than for the others. For wall lesion depth the CSEB group also presented the smallest mean values of wall lesion depth when compared to the others (P<0.0001) for all comparisons using Tukey's test. Regarding outer lesion depth, all adhesives showed statistically similar behavior. SEM evaluation of the morphologic appearance of caries lesions confirmed the statistical results showing small caries lesion development for cavities restored with CSEB adhesive system, which may suggest that this adhesive system interdiffusion zone promoted a good interaction with subjacent dentin protecting the dental tissues from recurrent caries.
American journal of dentistry 04/2010; 23(2):93-7. · 1.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 μm × 15 μm area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380–750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide (Pola Office, SDI- Australia) agent on the micromorphology and surface roughness of sound enamel using an Atomic Force Microscope (AFM). METHODS: Enamel blocks (4 x 3 x 2 mm) were cut from the coronal part of human embedded third molar. No polishing was made on enamel surfaces to maintain them with natural roughness. The enamel blocks were treated with 35% hydrogen peroxide (HP). The bleaching procedure consisted of 4 applications of the agent on enamel surfaces for 10 minutes each. Surfaces images were obtained in 10X10m2 areas using an AFM to observe the topography and to determine the average roughness (Ra), root mean square (Rms) and power spectral density (PSD). The blocks were submitted to the same analyses before and after the bleaching procedure. The initial records were used as a control of each block. RESULTS: The PSD analysis allowed to identify the morphological changes on the surfaces and the Ra and RMS parameters were less representative for these analysis. CONCLUSION: The methodology allowed to determine the effect of the bleaching procedure and to estimate quantitatively the gloss parameter.