Open Access

Mesenchymal stem cells (MSCs) are an attractive cell source for Regenerative Dentistry in particular due to their ability to differentiate towards osteoblasts, among other lineages. Tooth and jaw bone loss are frequent sequelae of traumatic and pathological conditions in both the young and the elderly and must be met by appropriate prosthetic replacements. For successful osseointegration of the dental implant a sufficient bone level is necessary. Besides the utilization of bone autografts or synthetic biomaterials, medical research is more and more focused on the utilization of MSCs. Compared to cells obtained from liposuction material, ectomesenchymal stem cells derived from the head area e.g. out of dental follicles or particulate, non-vascularized bone chips show a higher differentiation potential towards osteoblasts.

Renewable resources gain increasing interest as source for environmentally benign biomaterials, such as drug encapsulation/release compounds, and scaffolds for tissue engineering in regenerative medicine. Being the second largest naturally abundant polymer, the interest in lignin valorization for biomedical utilization is rapidly growing. Depending on resource and isolation procedure, lignin shows specific antioxidant and antimicrobial activity. Today, efforts in research and industry are directed toward lignin utilization as renewable macromolecular building block for the preparation of polymeric drug encapsulation and scaffold materials. Within the last five years, remarkable progress has been made in isolation, functionalization and modification of lignin and lignin-derived compounds. However, literature so far mainly focuses lignin-derived fuels, lubricants and resins. The purpose of this review is to summarize the current state of the art and to highlight the most important results in the field of lignin-based materials for potential use in biomedicine (reported in 2014–2018). Special focus is drawn on lignin-derived nanomaterials for drug encapsulation and release as well as lignin hybrid materials used as scaffolds for guided bone regeneration in stem cell-based therapies.

We present herein a new class of resin formulations for stereolithography, named FlexSL, with a broad bandwidth of tunable mechanical properties. The novel polyether(meth)acrylate based material class has outstanding material characteristics in combination with the advantages of being a biocompatible (meth)acrylate based processing material. FlexSL shows very promising results in several initial biocompatibility tests. This emphasizes its non-toxic behavior in a biomedical environment, caused mainly by the (meth)acrylate based core components. A short overview of mechanical and processing properties will be given in the end. The herein presented novel FlexSL materials show a significant lower cytotoxicity in contrast to commercial applied acrylic stereolithography resins. Further biocompatibility tests according to ISO 10993 protocols are planned. On the one hand, there are technical applications for this material (e.g. flaps, tubes, hoses, cables, sealing parts, connectors and other technical rubber-like applications), and on the other hand, broad fields of potential biomedical applications in which the FlexSL materials can be beneficial are obvious. Especially these could be small series production of medical products with special flexible material requirements. In addition, the usage for individual soft hearing aid shells, intra-operative planning services and tools like intra-op cutting templates and sawing guides is very attractive. The possibility to modify the FlexSL resins also for high-resolution applications makes it possible to manufacture now very flexible micro-prototypes with outstanding material characteristics and very fine structures with a minimum resolution of 20 mym and a layer thickness of minimal 5 myrn. These resin formulations are applicable and adjustable to other stereolithographic equipment available on the market.