## 1 Introduction  
Temporary filling materials are used in many procedures and techniques in dentistry. In endodontics, they can be used in multiple-visit approach and/or after endodontic treatment until the final restoration is placed. The main goals of root canal treatments (RCTs) are undoubtedly the prevention or the resolution of periapical lesions and the retention of the function of the treated teeth as much as possible. The most significant factors leading to RCT failure are fundamentally related to the etiopathogenesis of endodontic diseases: the bacteria. In fact, endodontic pathologies are caused by endodontic microorganisms and their by-products, thus, its successful treatment strictly depends on the efficiency of bacteria eradication and recontamination prevention. Therefore, the basic goal of RCTs is to eliminate microorganisms from the root canal system and to remove any biological substrate which could aid microbial growth, such as pulp tissue remnants, through adequate chemo-mechanical disinfection of the endodontic system. Moreover, the quality of chemo-mechanical debridement is not the sole factor able to affect the long-term clinical outcome. As a matter of fact, a tridimensional root canal filling is required to preclude bacterial recolonization of the endodontic system. Quality of both the root canal obturation and the coronal restoration influence the success rates of RCTs, confirming that satisfactory root fillings and proper coronal sealing are associated with an optimum root canal treatment outcome. It is important to underline that after endodontic treatment, at least an immediate dentinal conditioning and sealing with a preliminary build-up using adhesive techniques is recommended, to reduce risks of dentinal contamination and to improve bonding strength of the final restoration [1]. Temporary filling materials can be used also in vital pulp therapies (pulp capping, apexogenesis), apexification or regenerative procedures until these treatments are completed [2; 3; 4]. Vital pulp therapies consists in the placement of biocompatible materials on the exposed pulp tissue to preserve its health, stimulate repair by mineralized tissue formation [4] and allow continued root development along the entire root length (apexogenesis) [3]. If the pulp is irreversibly inflamed or necrotic, root-end closure procedures are required when the apex has not fully formed. In fact, pulpal necrosis in permanent teeth that have not completed their root development leads to teeth with a very short root, roots with very thin walls and an inadequate crown-root ratio, which overshadows their survival prognosis [2; 3]. The traditional apexification technique used calcium hydroxide (Ca(OH)\({}_{2}\)) as intracanal dressing, a strong base with a high pH (approximately 12), that was originally used in endodontics as a direct pulp-capping agent. Ca(OH)\({}_{2}\) is formed by a powder that when in contact with an aqueous fluid dissociates into calcium and hydroxyl ions. This reaction induces a hard-tissue deposition and high antimicrobial activity. that the study was made on deciduous teeth, instead of immature permanent teeth. More recently, another type of apexification named as \"apical MTA plug\" was described using calcium silicate materials, formed by a biocompatible powder with fine hydrophilic particles that hardens in the presence of humidity. Apexification presents the limitations of an interrupted root development, leaving the tooth with a fragile root structure and a poor crown-to-root ratio leading to higher risk of root fracture [2]. An alternative endodontic procedure for the treatment of necrotic immature teeth that may promote further root development by attempting to regenerate the pulp-dentin complex is regenerative endodontic procedure (REP). This conservative two-step procedure consists of the use of a combination of antimicrobials to reduce infection, no canal walls instrumentation, and induced apical bleeding to form a blood clot tightly sealed into the root canal in order to promote healing.