Acidic beverages, such as soft drinks (orange juice, and cola), or ethanol (whisky), can produce erosion of resin composites. The surface degradation of resin materials is related to the content and distribution of the fillers, the composition of the matrix resin, and the effect of silane surface treatment on the fillers. Direct Class II composite restorations can be placed at an acceptable standard if the cervical margin is in sound enamel. When the adhesive restorations are located below the cement-enamel junction (CEJ) and cervical lesions have no enamel, the quality of the marginal integrity is questionable. Below the CEJ, the bond with dentin is weaker: The polymerization shrinkage can result in gap formation between composite resin and the cavity walls. Marginal gap formation contributes to microleakage and permits the passage of oral fluids and bacteria from the oral cavity. It becomes a source of post-operative sensitivity, pulpal inflammation and recurrent caries. To reduce these effects, a better option to the conventional resin technique has been suggested: The Class II open-sandwich restorations: Glass-ionomer cement (GIC) or resin-modified glass-ionomer cement (RMGIC) is placed between the dentin cervical margins and occlusal composite restoration. GICs and RMGICs have been shown to be less able to seal margins and can dissolve over time in the oral environment. Recently, flowable resin composites with lower filler content andfar lower viscosity have been recommended as liners at CEJ margins of the proximal box of Class II composite restorations: A layer of flowable materials at the gingival floor in cementum margins of Class II composite restorations gets a better marginal seal of the restoration, and is an ideal choice for use in a open-sandwich technique.
Although the mechanical properties of these materials have been improved substantially, their antibacterial properties are still limited. The bacterial accumulation on the surfaces of restorative materials can provide the bacterial source leading to the development of secondary caries and periodontal diseases. Bacterial accumulation is highly dependent on the characteristics of the material surface and the roughness of resin composites can influence the oral biofilm adherence. Biofilm formation is a stepwise process initiated by adhesion of planktonicbacteria onto the surface of a tooth or other structures in the oral cavity. This process progresses from colonization and coadhesion, via growth and maturation, to detachment and spread of the microorganisms from the biofilm. The physical and chemical properties of the surface affect the feasibility of bacterial infection. Correlations between bacterial adhesion and various surface characteristics (chemical composition, surface energy, surface roughness and presence of functional groups on the surface) have been intensively investigated in an attempt to reduce bacterial adhesion through surface modification.
The objective of this in vitro study was to evaluate the surface roughness of four flowable composites (SureFil SDR flow, TetricEvoFlow, Esthet-X Flow, Amaris Flow HT) after exposure to acidic and alcoholic drinks using a Leica DCM (Dual Core Measuring) 3D microscope. The null hypothesis of the study was that there is no significant difference in surface roughness of the evaluated flowable composites.