Qualitative and Quantitative Evaluation of Cytotoxicity of Five Different One-Step Self-Etching Adhesives.

PURPOSE: To qualitatively and quantitatively compare the cytotoxic potentials of five different one-step self-etching adhesives: Prime&Bond One-Select (PB-OS), Optibond All-in-One (OB-AIO), G-Bond (GB), Clearfil Universal Bond (CUB), Single Bond Universal (SBU). MATERIALS AND METHODS: During the first stage of the study, the cytotoxic activities of the test materials were evaluated qualitatively using the direct contact method. In this method, the test materials were placed directly into a monkey kidney epithelial cell culture medium. Reaction zones which occurred in the culture medium were evaluated, in addition to the density and changes in the morphology of the cells. During the second stage, the cytotoxic potential of four different dilutions (1%, 0.1%, 0.01%, 0.001%) of the test materials on L929 rat fibroblast cells was quantitatively evaluated at three different time periods (24 h, 48 h, 72 h) with the MTT tetrazolium-based assay. RESULTS: In the first stage, a zone exceeding 1 cm was observed around or below SBU, CUB, GB and OB-AIO. In PB-OS, the zone borders were approximately 1 cm. In the second stage after the MTT assay, CUB was the most cytotoxic after 24 h, GB and SBU after 48 h, and OB-AIO after 72 h. CONCLUSION: All adhesives tested showed different degrees of cytotoxicity, which statistically significantly increased with dose. Changes were seen related to time.

One-year Clinical Performance of Flowable Bulk-fill Composite vs Conventional Compomer Restorations in Primary Molars.

PURPOSE: To evaluate the clinical performance of a flowable bulk-fill composite vs a compomer in Class II cavities of primary molars. MATERIALS AND METHODS: In a clinical study, 100 restorations were placed in two randomly assigned comparable Class II cavities in 32 children (aged 6.7 ± 1.2 years) with at least one bulk-fill composite (Venus Bulk Fill, Heraeus Kulzer) and one compomer (Dyract eXtra, Dentsply). After caries excavation, the adhesive Scotchbond Universal (3M Oral Care) was applied in self-etching mode. According to the manufacturer's instructions, Venus Bulk Fill was used for the entire Class II cavity of primary molars without a cover layer. After visible-light curing, both restorations were finished and polished. Both restorative materials were evaluated at baseline and after one year, including esthetic, functional, and biological parameters, using the FDI criteria. The Mann-Whitney U-test was used to determine the difference in the complete scores at baseline and after one year (p < 0.05). RESULTS: After one year, 99 restorations were reevaluated; one tooth had exfoliated physiologically. Concerning the esthetic parameters, Dyract eXtra showed slightly higher scores than Venus Bulk Fill. Both materials showed similar scores regarding functional and biological parameters. No severe postoperative sensitivities or side-effects were reported. There was no statistically significant difference between the performance of Venus Bulk Fill and Dyract eXtra for primary molars. CONCLUSION: The flowable bulk-fill composite Venus Bulk Fill can be considered as an alternative material for clinical use in primary teeth, but longer-term studies might still be needed.

Optical Evaluation of Enamel Microleakage with One-Step Self-Etch Adhesives.

OBJECTIVE: In this in vitro study, cross-polarization optical coherence tomography (CP-OCT) was used to evaluate microleakage in dental composite restorations bonded to enamel with two types of one-step self-etching (SE) adhesives. BACKGROUND DATA: One-step SE adhesives were proposed to simplify bonding of composite restorations. However, bonding of these simplified adhesive to dental enamel is still questionable. OCT is a promising diagnostic tool that allows micron-scale imaging of biological tissues and structures. METHODS: Class-V cavities (4-mm diameter × 1-mm depth) were prepared on the labial surfaces of extracted human anterior teeth with margins and floor located in enamel. The cavities were then divided into two groups (n = 5) and restored with either Tetric N-Bond Universal (Ivoclar Vivadent, Liechtenstein) or Palfique Bond (Tokuyama Dental Corporation, Japan), followed by Estelite Flow Quick flowable composite (Tokuyama Dental Corporation). After storage in 100% humidity for 24 h, specimens were immersed in ammoniacal silver nitrate solution for another 24 h. Later, they were rinsed and immersed in photo-developing solution under fluorescent light for 8 h. CP-OCT at 1310 nm center wavelength was used to scan seven two-dimensional cross-sectional images from each specimen. Each cross-sectional image was analyzed using ImageJ software to quantify interfacial microleakage at the cavity floor. RESULTS: Student's t-test showed significant difference between the tested adhesives (p < 0.05). Palfique Bond adhesive presented inferior interfacial adaptation as it obtained higher values of floor microleakage compared to Tetric N-Bond Universal adhesive group. CONCLUSIONS: CP-OCT enabled nondestructive quantitative assessment of microleakage in enamel dental restorations.

Bond Strength of One-Step Adhesives under Different Substrate Moisture Conditions.

OBJECTIVES: The aim of this study was to evaluate the bond strength of one-step adhesive systems to dry or moist dental substrate. METHODS: Thirty human third molars were sectioned into two halves, in the mesio-distal direction, parallel to the long axis of the tooth. Each half was embedded in a polystyrene resin cylinder so that the buccal/lingual surface remained exposed. This exposed surface was abraded to obtain both flat exposed enamel and dentin. The samples were randomly allocated according to the adhesive system (Xeno III, Adper Prompt and iBond) and moisture condition (dry and moist). The substrates were air-dried for 30 s for dry condition, while the moist substrates were re-wet with 2.5 mul of distilled water after drying. After the adhesive procedures, two resin composite cylinders were build-up on dentin and enamel substrates, totaling four per sample. A shear load was applied to the samples at a crosshead speed of 0.5 mm/min until failure. Data were statistically analyzed by three-way ANOVA and the Tukey test (alpha=0.05). RESULTS: The evaluated one-step adhesives showed higher bond strength to dentin than enamel. The iBond presented better bond performance to moist substrate and Xeno III to dry substrate. The moisture condition did not interfere in the performance of Adper Prompt. The Xeno III and iBond presented higher bond strength than the other adhesives to both dry and moist substrates. CONCLUSIONS: The moisture condition of substrate interfered in the performance of one-step self-etching adhesives and the best moisture condition was material dependent.