## 3 Results
### Mechanical Properties  
Both control and composites presented lower values of compressive strength than the bone tissue; however, the scaffolds coated with collagen showed values closer to the bone (Table 3). There was a statistically significant difference in terms of compressive strength between all the scaffolds and the control; moreover, groups with collagen (G1, G2, and G3) showed a significantly higher compressive strength than noncollagen groups (G4, G5, and G6) (Table 3), indicating that collagen improved the mechanical resistance of the scaffold materials. Figure 1: Scanning electron microscopy surface (**A**,**C**,**E**,**G**,**I**,**K**) and cross-section (**B**,**D**,**F**,**H**,**J**,**L**) images of the composite scaffolds made of polylactic-co-glycolic acid (PLGA) and biphasic ceramic (HA + \(\beta\)-TCP) at different ratios with G1: 50/50 (**A**,**B**), G2: 60/40 (**C**,**D**), and G3: 40/60 (**E**,**F**) and without G4: 50/50 (**G**,**H**), G5: 60/40 (**I**,**J**), and G6: 40/60 (**K**,**L**) collagen impregnation. In all groups, a structure with open pores and visible interconnectivity was produced. In groups G1, G2, and G3, collagen was able to coat both PLGA and HA + \(\beta\)-TCP, although group G3 exhibited several agglomerated ceramic particles. The groups without collagen coating presented a rougher morphology, and the HA + \(\beta\)-TCP particles seemed separated from the matrix; moreover, the agglomerates increased by increasing the amount of ceramic (G5 \(<\) G4 \(<\) G6). Magnification 60\(\times\). Figure 3: Chemical analysis by an energy-dispersive spectrometer (EDS) of all composite groups made of polylactic-co-glycolic acid (PLGA) and biphasic ceramic (HA + \(\beta\)-TCP) at different ratios: G1, 50/50 + collagen (**A**); G2, 60/40 + collagen (**C**); G3, 40/60 + collagen (**E**); G4, 50/50 (**B**); G5, 60/40 (**D**); G6, 40/60 (**F**); and control group (**G**), which revealed the presence of carbon (C), oxygen (O), calcium (Ca), and phosphorus (P). Figure 2: Scanning electron microscopy images of samples made of polylactic-co-glycolic acid (PLGA) and biphasic ceramic (HA + \(\beta\)-TCP) at a ratio of 60/40 in G2 with collagen (**A**) and 60/40 in G5 without collagen (**B**). (**A**) The ceramic particles within the matrix were covered by collagen, which created a bond holding the ceramic on the PLGA and resulting in higher mechanical properties. Isolated HA + \(\beta\)-TCP could be detected probably because of the sectioning of the samples by scalpel. (**B**) There is a lack of bond between PLGA and HA + \(\beta\)-TCP and ceramic scattered in the matrix is present. Magnification 150\(\times\). Equally, the elastic modulus was statistically higher in groups coated with collagen (G1, G2, and G3) than in noncoated groups (G4, G5, and G6); however, all the scaffolds exhibited a significantly lower stiffness than the control (Table 4). The mechanical properties of the evaluated scaffolds were not affected by the amount of biphasic ceramic added. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Groups (PLGA/HA + \(\beta\)-TCP)** & **Absorption Time** & **Liquid Height** & **Reached Sample** & **Drop** \\  & **(s)** & **(mm)** & **Center** & **Formation** \\ \hline G1 (50/50) + Collagen & 129 & 10 & Yes & No \\ G2 (60/40) + Collagen & 146 & 5 & Yes & Yes \\ G3 (40/60) + Collagen & 157 & 3 & Yes & Yes \\ G4 (50/50) & \({}^{*}\) & 1 & No & Yes \\ G5 (60/40) & \({}^{*}\) & 1 & No & Yes \\ G6 (40/60) & \({}^{*}\) & 1 & No & Yes \\ Control Bio-Oss Block® & 2 & 10 & Yes & No \\ \hline \hline \end{tabular}  
[PLGA: polylactic-co-glycolic acid; HA + \(\beta\)-TCP: biphasic ceramic].  
\end{table} 
Table 2: Characterization of the wettability of the composite and control groups. In the groups without collagen impregnation there is no liquid absorption (*).