## 1 Introduction  
Polymeric materials are widely used as biomaterials because of their great flexibility in controlling their properties and processing through the manipulation of their composition and chemical structure [1; 2; 3]. Natural and mainly synthetic polymers are gaining a great deal of attention in the field of tissue engineering for bone and other mineralized tissue applications [1; 2; 4]. The synthetic polymers most commonly used for the production of scaffolds are polylactic acid (PLA), polyglycolic acid (PGA), and their copolymer polylactic-co-glycolic acid (PLGA).  
PLGA is the most used because it offers better control of its properties by adjusting the monomer percentage [2; 3]. In addition, it is nontoxic, as the products resulting from its degradation are lactic acid and glycolic acid, which are eliminated in the form of carbon dioxide and water [3; 5; 6; 7]. However, before being metabolized, the acids can induce adverse reactions, such as inflammation, in the surrounding tissues by altering the pH of the region. A technique used to neutralize the acidity of degradation products is the addition of alkaline substances [8]. In this light, ceramic particles could be used as additives to PLGA in order to provide a pH buffering effect at the polymer surface and, thus, avoid the local reduction of pH, which could in turn damage bone cell health and hamper new bone growth [9].  
Calcium phosphates, besides being alkaline materials, have calcium and phosphorus, which are natural constituents of the bone and, therefore, would neutralize the pH and increase the osteeconductive properties of PLGA [4; 5; 8; 10; 11; 12]. The use of calcium phosphates combined with PLGA enhances alkaline phosphatase activity, which is crucial for osteoblastic differentiation [13] and acts as a reinforcement to improve the mechanical strength of the scaffold [3]. The main disadvantage of using PLGA is its hydrophobic nature, which prevents penetration and adhesion of the cells [14; 15]. However, surface modification through the addition of natural polymers can be used.  
Type I collagen could be a good option as it represents about 90% of the proteins in the bone extracellular matrix, is highly hydrophilic, it is considered a weak antigen [16], and an immune response against it is very rare [17]. [PERSON] et al. [16] reported that less than 3% of the patients presented adverse reaction, inflammation, and granuloma; hypersensitivity to collagen was found in 2% to 4% of patients, and only 1% presented allergy during the postoperative. Nevertheless, collagen could contribute to the hydrophilicity, biocompatibility, porosity, biodegradability, and osteoconduction of composite scaffolds. Collagen would interact with the various proteins mimicking the natural environment of the cells, and it could perform a structural role enhancing the mechanical properties [15; 18; 19; 20; 21; 22; 23; 24]. Composites of collagen and Hydroxyapatite (HA) showed improved bioactivity and in vitro mineralization [25], higher bone formation, as well as enhancement of elastic modulus [26], when compared to collagen alone. Polymers coated with collagen have been shown to allow attachment, survival, and proliferation of human neural cells [17], increase and accelerate bone formation [27], and enhance the spreading of endothelial cells [28]. Some limitations, however, exist when working with collagen, as it is costly, it has a low biostability, owing to its rapid degradation in the biological environment, and there are problems related to its antigenicity [29].  
The objective of this study was to develop a new class of composite porous scaffolds of PLGA and biphasic ceramic with or without collagen impregnation to be used for bone regeneration in the oral and maxillofacial district and to investigate their physical-mechanical properties in order to tailor their usage accordingly.