Osteointegration of Porous Poly-ε-Caprolactone-Coated and Previtalised Magnesium Implants in Critically Sized Calvarial Bone Defects in the Mouse Model

Abstract

Metallic biomaterials are widely used in maxillofacial surgery. While titanium is presumed to be the gold standard, magnesium-based implants are a current topic of interest and investigation due to their biocompatible, osteoconductive and degradable properties. This study investigates the effects of poly-ε-caprolactone-coated and previtalised magnesium implants on osteointegration within murine calvarial bone defects: After setting a 3 mm × 3 mm defect into the calvaria of 40 BALB/c mice the animals were treated with poly-ε-caprolactone-coated porous magnesium implants (without previtalisation or previtalised with either osteoblasts or adipose derived mesenchymal stem cells), porous Ti6Al4V implants or without any implant. To evaluate bone formation and implant degradation, micro-computertomographic scans were performed at day 0, 28, 56 and 84 after surgery. Additionally, histological thin sections were prepared and evaluated histomorphometrically. The outcomes revealed no significant differences within the differently treated groups regarding bone formation and the amount of osteoid. While the implant degradation resulted in implant shifting, both implant geometry and previtalisation appeared to have positive effects on vascularisation. Although adjustments in degradation behaviour and implant fixation are indicated, this study still considers magnesium as a promising alternative to titanium-based implants in maxillofacial surgery in future.

Clinical, industrial, and research perspectives on powder bed fusion additively manufactured metal implants

“…In an effort to further optimise degradation kinetics, the use of a polycaprolactone (PCL) coating has been investigated in a mouse [149,151]. calvarial defect model, however the rate of resorption remained sufficiently high that voids were observed between the implant surface and mineralised bone after 84 days [191]. Magnesium alloys have been the most widely used resorbable alloys [192,193], and as a result a wide range have been processed by L-PBF, including pure Mg, WE43, AZ91 and several Mg-Zn alloys [167,189,190,[194][195][196][197][198][199][200].…”

“…On the other hand, discussion of coverage quality achieved is rare. When investigated, poor uniformity across the internal structures of lattices is noted, for example in the integration of poly-ε-caprolactone and poly(3-hydroxybutyrate) [191].…”

Ten Years of Micro-CT in Dentistry and Maxillofacial Surgery: A Literature Overview

“…Micro-CT allowed to demonstrate that a bisphosphonate treatment for osteoporosis, can invert the negative effect of osteoporosis on osseointegration, promote osseointegration itself and, the fixation of dental implants in autologous bone grafts under osteoporotic condition [117]. Furthermore, bone tissue response and osseointegration were investigated in experimental animal protocols, in relation to a bioactive silicate coating [118], lightweight implants [119], and poly-ε-caprolactone-coated and previtalized magnesium implants, manufactured by selective laser melting technology [120], alternative to traditional implants in MFS and new implants with modified surfaces, in comparison with commercially available dental implants [121]. Titanium implants were microtomographic observed and induced osteolysis was addressed [122], as well as newly formed bone in bioactive coated implants [118].…”

“…Histomorphological analysis were carried out for in vivo studies about the effects of bioactive coatings [118], bone graft substitutes [104,105], as well as confocal analysis, to examine the presence of live and dead cells after seeding on the experimental scaffolds at various days of culture [110]. Histology, as a traditional destructive analysis, was also reported combined with micro-CT for various applications, to assess: root fractures [86]; alveolar bone loss [114]; bone morphological changes [115]; new bone formation [96,102]; osseointegration in osteoporosis [117]; inflammatory response and vascularization using modified silk fibroin scaffolds [108]; bone tissue response of new zirconia implants with modified surfaces [121]; titanium [119]; and magnesium [120] implants for MFS and, maxillofacial trabecular bone microarchitecture and damage [123]. Moreover, immunohistochemical (IHC) analysis was performed with histology [109] and with immunofluorescent (IF), in studies related to tissue engineering applications [97].…”

“…In this scenario, micro-CT analysis is defining a new role, also considering that conventional intra-oral scanner could be limited in terms of accuracy [9] for the acquisition of specific geometries and sizes. CAD/CAM, 3D printing, and AM benefit from microtomographic analysis to develop and validate solutions in dentistry, and MFS [120]. Rimawi et al presented an integrated approach applying intra-oral scanner, CBCT, micro-CT, 3D printing, and stereomicroscopy for temporary restoration of auto-transplanted teeth [67].…”