RESUMO
OBJECTIVES: The aim of the present study was to evaluate hybrid layer thickness of primary molars sectioned with diamond, carbide and ultrasonic CVD burs. STUDY DESIGN: The occlusal enamel surfaces often molars were removed and superficial dentin was exposed. Three standardized cavities were prepared at mesial, central and distal exposed dentin with diamond, carbide and ultrasonic CVD burs, respectively. A self-etching adhesive system (Adhese, Ivoclar/Vivadent) was applied to prepared cavities and composite resin Z100 (3M/ESPE) was inserted according to manufacturers'instructions to hybridized dentin. Samples were light-cured and the crown was sectioned mesio-distally dividing the restored cavities in two halves which were observed under scanning electron microscopy (SEM), in order to quantitatively evaluate hybrid layer thickness (microm). Three repeated measures were performed at mesial, central and distal sites and mean values obtained were submitted to one-way analysis of variance (ANOVA). RESULTS: Data (mean +/- sd) obtained were (microm): 2.69 (0.44), 3.38 (1.23) and 2.72 (1.18)for diamond, carbide and CVD burs, respectively. No differences were observed among groups (p > 0.05). The adhesive systems promoted mechanical retention, uniform and continuous hybrid layer and resin tags formation at all dentin sites for all instruments tested. CONCLUSION: The results suggest that the minimally invasive cavities prepared with diamond, carbide and CVD for ultrasound, promoted hybrid layer formation with a similar thickness regardless the bur used.
Assuntos
Compostos Inorgânicos de Carbono/química , Resinas Compostas/química , Preparo da Cavidade Dentária/instrumentação , Materiais Dentários/química , Dentina/ultraestrutura , Diamante/química , Piezocirurgia/instrumentação , Resinas Acrílicas/química , Colagem Dentária , Adesivos Dentinários/química , Desenho de Equipamento , Humanos , Cura Luminosa de Adesivos Dentários , Teste de Materiais , Microscopia Eletrônica de Varredura , Dente Molar/ultraestrutura , Cimentos de Resina/química , Dióxido de Silício/química , Propriedades de Superfície , Dente Decíduo/ultraestrutura , Zircônio/químicaRESUMO
This study evaluated Streptococcus mutans biofilm adhesion on the surface of three composite resins (nanofilled, Filtek Z350, 3M ESPE, Salt Lake City, UT, USA; nanohybrid, Vit-1-escence, Ultradent Products, South Jordan, UT, USA; and microhybrid, Esthet X, Dentsply, Milford, DE, USA) following different finishing and polishing techniques. Sixty standardized samples (6 × 3 mm) of each composite were produced and randomly divided into three finishing and polishing treatments (n=20): 1) control group: composite resin surface in contact with Mylar matrix strips with no finishing or polishing performed, 2) Sof-Lex aluminum oxide disc technique (3M ESPE, and 3) carbide bur finishing and Astrobrush polishing technique (Ultradent). Half the samples of each group were incubated in human saliva for 1 hour, and all the samples were subjected to S mutans (ATCC 35688) biofilm development. The mean log of CFU/mL present in the S mutans biofilm was calculated, and data were statistically analyzed by three-way analysis of variance and the Tukey test (p<0.05). Human saliva incubation promoted a significant increase of bacterial adherence on all three of the composites' surfaces, regardless of the polishing treatment performed (p<0.05). Of the three, the nanofilled composite (Filtek Z350) had the lowest bacterial adherence with each of the finishing and polishing techniques despite the presence or absence of human saliva (p<0.05). Mylar matrix strips (control group) promoted the lowest bacterial adhesion on the surface of the microhybrid and nanofilled composites in the absence of human saliva.
Assuntos
Aderência Bacteriana/fisiologia , Biofilmes , Resinas Compostas/química , Materiais Dentários/química , Polimento Dentário/métodos , Streptococcus mutans/fisiologia , Óxido de Alumínio/química , Carga Bacteriana , Biofilmes/crescimento & desenvolvimento , Compostos Inorgânicos de Carbono/química , Polimento Dentário/instrumentação , Humanos , Teste de Materiais , Nanocompostos/química , Polietilenotereftalatos/química , Saliva/microbiologia , Compostos de Silício/química , Propriedades de Superfície , Temperatura , Fatores de Tempo , Compostos de Tungstênio/química , Água/químicaRESUMO
Fourier-Transform (FT)--Raman spectroscopy was used to evaluate in vitro the degree of conversion (DC) of Charisma dental composite cured by three different light curing units (LCUs) using soft-start and normal protocols. Eighty circular blocks of resin (7 mm in diameter x 2.5 mm thick) were prepared and cured using the following sources: halogen light (Degulux soft-start, n = 20, G1-G2), low power light emitting diode (LED) with transparent polymer tip (LD13, n = 20, G3-G4) and fiber optic tip (LD13, n = 20, G5-G6) and, finally, high power LED (Radii, n = 20, G7-G8). The top and bottom surfaces of the blocks were analyzed by FT-Raman spectroscopy. The respective DCs were estimated calculating the peak height ratio of the aliphatic C=C (1640 cm(-1)) and aromatic C=C (1610 cm(-1)) Raman modes. The DC at the surfaces ranged between 50% and 60% for the top and 46% and 58% for the bottom. The halogen light and high power LED LCUs with the soft-start and normal protocols produced the highest DC values of dental composite at both surfaces (p < 0.001). Curing by low power LED in the soft-start protocol did not produce adequate DC at the depth of 2.5 mm. The type of LCU light guide tip did not present a significant statistical difference in the final DC of the dental composite (p > 0.05).