Table 2.
Description of the 22 main research works found after the bibliographic search that, both in vitro and in vivo, evaluate the regenerative efficacy and the mechanical properties of scaffolds obtained with different fabrication techniques *.
| Author/Year | Fabrication Technique | Study Design | Materials | Results |
|---|---|---|---|---|
| Cao H. 2010 [31] |
Solvent casting | In vivo: 40 rats with femur defects | Scaffolds made with HA and PGA-betaTCP at different % (1:1 and 1:3) were compared. | The PGA-betaTCP bioblock (1:3) obtained a higher density and new bone formation than the rest 90 days after surgery, as well as a reabsorption rate appropriate to the process. |
| Yang L. 2019 [32] |
TIPS | In vivo: Nine female New Zealand white rabbits were used, and two operations were performed on each. | PLGA and PLGA/bioglass scaffolds were compared. | Both implants had similar porosities (93.926% and 93.048% respectively) while the scaffold with bioglass showed a higher rate of cell adhesion. |
| Brie J. 2013 [33] |
SLA | In vivo: Eight bone implants in 8 patients | Hydroxyapatite | Three types of grafts were designed, two of which were solid and a third had macropores in the areas of attachment to the native bone. After healing, gaps were observed in the massifs on palpation, while the macropores formed a smooth interphase. |
| Staffa G. 2012 [34] |
SLA | In vivo: Sixty patients with large cranial defects. | Hydroxyapatite | None of the patients suffered rejection, spontaneous fracture, or mobilization of the graft and all reported good initial and long-term aesthetics. |
| Mangano F. 2013 [35] |
SLS | In vivo: Five patients with severe mandibular atrophy | Master alloy (Ti6Al4) | Blade-shaped dental implants were manufactured to rehabilitate atrophic maxillae. After 2 years of follow-up, all the implants were still in function and with good integration and good esthetic results. |
| Cox SC. 2015 [36] |
3D printing | In vitro: They were printed on the X-axis and the Y-axis for comparison. | HA (50%) and PVOH (polyvinyl alcohol) | Variation in mechanical resistance (0.88 MPA in the Y axis and 0.76 MPa in the X axis). However, PVOH degradation products were found in the Y-axis after the thermal treatment. |
| Inzana JA. 2014 [37] |
3D printing | In vivo: Defects were created in the femurs of 12 female mice:
|
Pure calcium phosphate bioceramic, coated with collagen and embedded in collagen. | The mechanical resistance of all the pure calcium phospate was significantly lower than that of the allografts, although none reached the values of the intact femur (19.4 ± 5.6 N mm). In terms of bone formation, the scaffolds were osteoconductors but poorly osteoinductors; they did not completely cure the defect on their own. |
| Torres, J. 2011 [38] |
3D printing | In vivo: Eight New Zealand rabbits in which a total of 16 bone blocks were placed in calvaria. | Monetite (calcium phosphate ceramic) | The surgical procedure was easy and fast. After 8 weeks, the 4 and 3 mm high blocks were fused to the bone surface and filled with 35% and 41% respectively of newly formed bone. |
| Lee JH. 2020 [39] |
FFF (MHDS) |
In vitro: Human osteoblasts were used to determine compatibility and appropriate drug concentration. | PCL with rifampicin | Successful scaffolds were developed for the treatment of osteomyelitis by printing at 60 °C so as not to alter the properties of the drug. |
| Zheng P. 2019 [40] |
FFF | In vivo: Scaffolds were placed in 9 female New Zealand rabbits with femoral defects for osteochondral regeneration | PCL-HA coated with mesenchymal stem cells and chondrocytes | This PCL-HA scaffold promoted increased joint cartilage repair compared to the PCL-HA unseeded control scaffolds, thus concluding that the use of chondrocytes and mesenchymal cells stimulates cartilage regeneration. |
| Lethaus B. 2012 [41] |
FFF | In vivo: Manufacture of mandibles prior to resection in 20 patients to pre-form the reconstruction plates. | Not applicable | They demonstrated great accuracy and significantly facilitated the process. |
| Roohani-Esfahani SI. 2016 [42] |
DIW. (Robocasting) | In vitro: Highly porous hexagonal architectural glass-ceramic structures were manufactured. |
Bioglass (Sr doped with Ca2ZnSi2O7(HT)) | Thanks to the optimization of the geometry, a compressive strength of 100–110 MPa and a high fatigue and flexural strength (30 MPa) were achieved: 150 times more than polymer and composite bioblocks and 5 times more than other made of bioceramics with similar porosity but different geometry. |
| Fu Q. 2011 [43] |
DIW. (Robocasting) | In vitro: Inks with 30% powder with low viscosity at 0° and high viscosity at 40 °C were used. An SBF was used to evaluate the properties. | Bioglass 6P53B | Compressive strength, with 60% porosity, of 136 ± 22 MPa, which remained above the values of the trabecular bone (77 MPa) after being immersed for 3 weeks in a simulated body fluid. |
| Hong SJ. 2009 [44] |
DIW (Robocasting) |
In vitro: Rat bone marrow stromal cells (rBMSC) were used. | PCL and PCL/HA | The HA-PCL scaffold with robotic dispensing has potential applications as a bioactive matrix. Despite showing limited cell adhesion, it proved to stimulate osteogenic differentiation. |
| Ma C. 2019 [45] |
DIW and DIW/Solvent casting |
In vitro: 3D and 2D scaffolds (membranes) were manufactured. All three groups of materials were cultured with fibroblasts in vitro. | PLLA, PLLA with tubular and spherical polypyrrole nanoparticles. | The nanoparticles increased the tensile strength (membranes from 100 to 250 MPa). Biocompatibility was satisfactory in all cases. Using these techniques, the 3D and 2D scaffolds were successful in optimizing the physiological microenvironment, which could be adapted to regenerate different tissues. |
| Franco J. 2010 [46] |
DIW. Robocasting | In vitro: The ink was created with 30–50% powder and Pluronic F-127 as hydrogel. | HA, b-TCP and HA/b-TCP with Pluronic F-127 solutions | A high pluronic content adds stability to the ink but, as a result, creates larger microporosities and less mechanical resistance. |
| Liu X. 2013 [47] |
DIW Robocasting |
In vivo: 30 male Sprague-Dawley rats in which calvarial defects were created in each parietal bone. | Bioglass 13-93. They were introduced into K2HPO4 to create a superficial layer of HA, or BMP-2 was added to the bioglass. | Both strategies both individually and in combination proved to be effective in improving bone regeneration of calvarial defects. |
| Abarrategi A. 2012 [48] |
DIW Robocasting |
In vivo:
|
Bioceramics (HA/betaTCP) with BMP-2 protein (study). As a control: scaffolds without BMP-2 in muscle and BioOss in bone. |
In muscle:
|
| Tovar N. 2018 [49] |
DIW. (Robocasting). | In vivo: Fifteen New Zealand rabbits with radial diaphysis defects. They were analyzed at 8 (n = 9), 12 (n = 3) and 24 (n = 3) weeks. | β-TCP | At 12 and 24 weeks, a large amount of bone was found which led to the regeneration of the marrow space. The amount of scaffold was much higher at 8 than at 12 and 24 weeks, between which there was not much difference. |
| Silva DN. 2008 [50] |
SLS and 3D printing | In vitro: Dry human skulls were used to measure and compare the accuracy of the techniques. | Gypsum powder and water were used as a binder. | The SLS and 3DP printing accuracy was acceptable; an error of 2.1% and 2.67% was obtained respectively when comparing the real skulls with those manufactured via these techniques from the CT. |
| Salmi M. 2013 [51] |
SLS, 3DP and PolyJet | In vitro: Dry human skulls were used to measure and compare the accuracy of the 3 techniques with a new measurement method. | Not applicable | Using the method used (based on positioning 6 balls on the 3D model, measuring the distance between them and determining their midpoint), they found considerably greater accuracy (0.18 ± 0.12%) with PolyJet technology as compared to SLS (0.79 ± 0.26%) and 3DP (0.67 ± 0.26). |
| Tagliaferri V. 2019 [52] |
FDM, SLS and MJF were compared. | In vitro: Six objects with different geometries were selected for analysis. | (Polyamide) Nylon 12 (in powder form for SLS and MJF and in filament form for FDM). | SLS and MJF have the advantage that several components can be manufactured at the same time. FDM technology has the greatest limitations due to the high time and cost, as well as the high environmental impact, which was minimal with the MJF technique. |
* Visit the acronyms section at the end of the paper for the description of the material and/or technique mentioned in this table.