## 1 Introduction  
Recently, the clinical application of regenerative medicine in the field of dentistry was verified by using different techniques and different therapeutic procedures in order to restore the main functions of dental tissues [1]. One such technique is using stem cells in therapeutic applications by injecting them solely or in combination with other molecules [2]. Hence, the injected cells are responsible for the regeneration of the damaged or missed dental tissues, thereby restoring their biological function and structure [1]. Dental pulp stem cells (DPSCs) are the first type of dental stem cells that were isolated from the pulp of human third molars [3]. Since then, mesenchymal stem cells (MSCs) of dental origin have been isolated from different dental tissues, such as (SHED) stem cells from human exfoliated deciduous teeth [4], (PDSCs) periodontal ligament stem cells [5], (SCAP) stem cells of apical papilla tissue of impacted third molars [6], (DFSCs) dental follicle stem cells [7] and stem cells from periapical cysts [8]. All these cells are derived from the same dental origin, but they vary in terms of MSC surface markers, and in their differentiation potential for different cell-lineages [9]. Human-derived dental pulp stem cells (hDPSCs) are considered an attractive and very promising source of stem cells for use in clinical applications for many reasons. First, teeth are easily collected at any dental clinic. Second, no ethical approval is required for teeth collection, because extracted teeth are considered medical waste [4]. Third, hDPSCs are tested and examined in a high manner. Fourth, these cells, just like MSCs, possess immunosuppressive activity [10]. Fifth, no change on their differentiation potential toward different lineages is observed after cryopreservation [9; 11; 12]. Sixth, they possess a high mineralization potential, which is characterized by the volume of the mineralized matrix produced through their differentiation process, indicating their high potential to regenerate and repair pulp and bone tissues [13]. Therefore, hDPSCs have high potential to differentiate into odonto/osteoblasts, making them a good candidate for future therapeutic applications to regenerate dentin and bone defects and restore damaged tooth structures [14]. The combinatorial strategy of using stem cells together with scaffolds and bioactive factors is a promising tissue-engineering approach that can be applied for the regeneration of dental and bone tissues [15; 16; 17; 18]. The accompanying scaffolds are made of biomaterials, such as biodegradable metals, bioactive ceramics, and biodegradable polymers, serving as 3D structures that promote such cellular processes as proliferation, migration and differentiation [19]. Additionally, those scaffolds can be modified using different treatments to enhance the secretion of biological molecules. For instance, the release of odonto/osteogenic factors as biological molecules results in increasing the activity of both cell types: endogenous and injected cells [19; 20; 21]. In recent years, Biodentine(tm) (BD) has gained attention as a novel 'dentin substitute'. This new biologically active material claims to improve such properties as physical qualities and handling, including its other wide range of applications, such as endodontic repair and pulp capping in restorative dentistry [22; 23; 24; 25]. Different studies have examined the role of BD in enhancing the odontogenic and osteogenic differentiation potential of DPSCs [22; 26; 27; 28]. However, the molecular signaling cascades that are activated through the differentiation process are not very well understood and remain to be elucidated. Since no previous studies have evaluated these networks, our study aims to investigate the odonto/steogenic potential of hDPSCs combined with the bioactive material Biodentine(tm) by studying the signaling networks at the molecular level: gene and protein levels.