## 1 Introduction  
The necessity of restorative materials for different clinical situations was responsible for the development of new versions among which the flowable materials play an important role. Resin based flowable materials are characterized by low viscosity and high elasticity, properties that make them highly recommended for the restoration of complex and difficult areas like the cervical portion of a tooth or the marginal ridges [1, 2]. Recently developed flowable materials are reported to have superior mechanical properties and wear resistance, making them applicable in a wide variety of restorative cases, some of them with mechanical properties similar to conventional resin matrix based restoratives [3, 4, 5]. Giomers represent a new development in the hybrid material category and consist in a stable glass-ionomer faze, on a glass core resulted from an acid-base reaction between fluoridated glass and poly-carboxylate acid, in the presence of water (\"Pre-Reacted Glass-ionomer filler\" or PRG). This material is proven to have anti-plaque effect, reducing the adherence of harmful bacteria to the tooth structure, is adequate for the treatment of hypersensitivity and non-cytotoxic to human teeth [6]. Appling PRG-technology to the filler in resin based composite materials gives them bioactive properties through fluoride release and recharge, similar to traditional glass-ionomers, but maintaining in the same time physical and esthetical properties of the composites [7; 8]. Flowable materials in the form of giomers have very specific clinical indications in the field of restorative dentistry, because of their flexibility and quality of adhesion to enamel and dentine [9]. Flowable giomers have a several applications in the practical field, in function with the filler percentage. The higher filler percentage and strong mechanical properties of B-F00, makes it able to withstand the restoration of occlusal anatomy, class V restorations and marginal ridges, where the highest forces are applied. A lower filler percentage and lower mechanical properties, but higher fluidity and wettability make B-F03 indicated for class V restorations, small fillings or as cavity liner, where the ability of a filling material to flow and fill all details are most important [10]. The B-F02 material with lower mechanical properties and lower filler percentage, make it suitable for small or superficial restorations (class I to III and class V) and also as cavity liner [10]. To the best of our knowledge, very few references are available in literature regarding these materials [11; 12; 13]. Giomers were characterized regarding optical properties, translucency and masking capacity [12], water sorption and solubility [11; 13]. Bioactive materials bring benefits regarding various protection trough fluoride release. The capacity to release a protective amount of fluoride is dependent on the hydric degradation of the incorporated bioactive glass. However, the interaction with oral fluids has consequences on the mechanical properties of a material and on the surface roughness [14]. Similar to glass-ionomers, giomers act like fluoride reservoirs, with the initial high concentration release phase lasting 24-48 h. This value will decrease over time, reaching a stable point in 3 to 5 weeks after application [7; 15]. Clinically, the most important aspect regarding fluoride release is the limitation of secondary caries, the main cause for direct restoration early replacement [16; 17; 18; 19; 20]. The PRG-filler (pre-reacted glass filler) technology proved effective against bacteria responsible for caries apparition, including _Streptococcus Mutans_[17; 21; 22]. The fluoride recharging capacity form the oral environment of giomer materials can benefit from the application of gels, varnishes, usage of fluoridated mouth wash or tooth paste. [20; 21; 22; 23]. Over time, the quantity of fluoride released into the oral environment will decrease, resulting in porous defects in the resin matrix [20; 23].