Abstract
The aim of this study was to evaluate the bond strength, bottom/top hardness ratio, marginal adaptation, and interfacial nanoleakage of regular viscosity bulk fill composites (RVBFC) and regular viscosity traditional composites (RVTC). Two RVBFC (Filtek Bulk Fill and Aura Bulk Fill) and two RVTC (Filtek Z250XT and Aura) were assessed. Forty conical cavities (4.8×2.8×4.0) were prepared in bovine dentin and restored with composites (n=10). After 24h in water, marginal adaptation was evaluated by staining with a caries detector. The top and bottom surfaces of the conical restorations were stained for five seconds and the gap percentage in the composite/dentin interface was determined using digital images on a measurement program (ImageTool). The Vickers microhardness was measured and the bottom/top microhardness ratio (B/T) was determined. Push-out bond strength test was performed in a universal testing machine (0.5mm/min) and failure modes were evaluated in a stereomicroscope (20×). Other specimens (n=3) were produced for interfacial nanoleakage evaluation. Data were analyzed using one and two-way ANOVA and Tukey's test (α=0.05). The gap percentage was higher in the bottom compared to the top. The B/T ratio of the Aura Bulk Fill was statistically lower than other composites. Push-out bond strength were similar among composites. The RVBFC presented lower nanoleakage than the RVTC in the bottom of the conical restoration and there was no difference among the materials in the top surfaces. In conclusion, Filtek Bulk Fill performed better than Aura Bulk Fill regarding the analyzed properties.
Highlights
One of the challenges in restorative dentistry is finding the balance between simple clinical protocols for restorations with composite resins and clinical longevity of restorations. [1] The traditional filling technique, consisting of multiple 2-mm composite increments, demands long chair time and increases the possibility of internal voids, which can affect mechanical properties of the composite [1]
Polymerization depth, marginal adaptation, and integrity of the hybrid layer are physical porperties that may affect the longevity of tooth restorations using regular viscosity bulk fill composites
This study aimed to analyze push-out bond strength, bottom/top hardness ratio, marginal adaptation, and interfacial nanoleakage of regular viscosity bulk fill composites in dentin cavities and compare the results obtained with traditional composite resins
Summary
One of the challenges in restorative dentistry is finding the balance between simple clinical protocols for restorations with composite resins and clinical longevity of restorations. [1] The traditional filling technique, consisting of multiple 2-mm composite increments, demands long chair time and increases the possibility of internal voids, which can affect mechanical properties of the composite [1]. [1] The traditional filling technique, consisting of multiple 2-mm composite increments, demands long chair time and increases the possibility of internal voids, which can affect mechanical properties of the composite [1]. Flowable and regular viscosity bulk fill composites are available in the market. Flowable bulk fill composites are used as cavity bases under a covering composite. Regular viscosity bulk fill composites have increased viscosity and most do not require a covering composite; they may be used to fill the entire tooth cavity [3]. Polymerization depth, marginal adaptation, and integrity of the hybrid layer are physical porperties that may affect the longevity of tooth restorations using regular viscosity bulk fill composites [4]. A weak bonding to the tooth structure increases the chance of microleakage, and favors adverse consequences such as postrestorative hypersensitivity, recurrent caries, marginal discoloration, and injury to the pulp [6]
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