Thomas Giraud

Research in implant dentistry has predominantly focused on bone regeneration, osseous volume maintenance, and successful osseointegration. However, soft tissue healing, which influences implant functional sealing, long-term stability, and esthetic integration, remains underexplored. This study investigated the effects of three xenogenic bone substitutes on gingival healing in vitro. Three experimental groups were established using extracts from bone substitutes diffusing through the OsteoBiol^® Evolution collagen membrane: two collagenated substitutes, OsteoBiol^® Gen-Os^® (Gen-Os) and OsteoBiol^® GTO^® (GTO), and one inorganic substitute, Bio-Oss^® (Bio-Oss). The substitutes were prepared in test tubes, and the extracts diffusing through the collagen membrane were used to evaluate human gingival cell (hGC) proliferation (MTT assay), migration (scratch assay), and growth factor release (ELISA). Angiogenic potential was assessed by endothelial cell proliferation, recruitment (Boyden chambers), and organization (Matrigel^® assays). The indirect interaction between stimulated gingival cells and human bone marrow mesenchymal stem cells (hMSC) was investigated by analyzing hMSC recruitment and osteogenic BMP-2 secretion. Collagenated GTO and Gen-Os significantly enhanced hGC proliferation and migration in the scratch assay, with 1.8-fold and 1.6-fold increases, respectively, compared to control. All three substitutes enhanced neoangiogenesis in vitro. VEGF and FGF-2 secretion was significantly higher with GTO, showing 5-fold and 5.7-fold increases, respectively, resulting in a 3.7-fold increase in tube formation compared to control. Collagenated materials promoted hMSC recruitment, whereas BMP-2 secretion was not affected by any material. The observed effects were higher with the collagenated Gen-Os and GTO, with 2.5-fold and 2.8-fold increases, respectively, than with the non-collagenated Bio-Oss, which showed a 1.5-fold increase. These findings demonstrate that collagenated bone substitutes enhance gingival healing and angiogenic potential through barrier membranes and confirm that stimulated gingival cells indirectly promote hMSC recruitment, indicating that bone substitute effects extend beyond bone regeneration to include soft tissue healing and inter-tissue communication.

A pre-hydrated thermosensitive collagenated biomaterial which sets at body temperature and maintains the space of the missing alveolar bone volume, OsteoBiol GTO^® (GTO), has been released as a bone substitute. This study was designed to check its angiogenic and osteogenic potentials compared to OsteoBiol Gen-Os^® (Gen-Os) and Geistlich Bio-Oss^® (Bio-Oss). Samples of materials were incubated in culture media to obtain the extracts. Collagen release was measured in the extracts, which were used to investigate human periodontal ligament (hPDL) cell proliferation (MTT), colonization (Scratch assays) and growth factor release (ELISA). The effects on endothelial cell proliferation (MTT) and organization (Matrigel^® assays) were also studied. Finally, endothelial and mesenchymal Stem Cell (hMSC) recruitment (Boyden Chambers) were investigated, and hMSC Alkaline Phosphatase (ALP) activity was measured. A higher collagen concentration was found in GTO extract, which led to significantly higher hPDL cell proliferation/colonization. All materials increased VEGF/FGF-2 growth factor secretion, endothelial cell recruitment, proliferation, and organization, but the increase was highest with GTO. All materials increased hMSC recruitment and ALP activity. However, the increase was highest with collagenated GTO and Gen-Os, which enhanced C5a and BMP-2 secretion. Overall, GTO has higher angiogenic/osteogenic potentials than the collagenated Gen-Os and the anorganic Bio-Oss. It provides a suitable scaffold for endothelial and mesenchymal stem cell recruitment, which represent essential bone regeneration requirements.

Resorbable hydrogels are widely used as scaffolds for tissue engineering. These hydrogels can be modified by grafting dendrimer-linked functionalized molecules (dendrigrafts). Our aim was to develop a tunable poly(L-lysine) dendrigrafts (DGL)/PEG-based hydrogel with an inverse porosity and to investigate its osteogenic potential. DGL/PEG hydrogels were emulsified in a surfactant-containing oil solution to form microspheres. The toxicity was evaluated on Human Vascular Endothelial Cells (HUVECs) and Bone Marrow Mesenchymal Stem Cells (hMSCs) with Live/Dead and MTT assays. The effects on HUVECs were investigated through C5 Complement expression by RT-PCR and C5a/TGF-β1 secretion by ELISA. Recruitment of hMSCs was investigated using Boyden chambers and their osteogenic differentiation was studied by measuring Alkaline Phosphatase activity (ALP) and BMP-2 secretion by ELISA. Adjusting the stirring speed during the emulsification allowed to obtain spherical microspheres with tunable diameters (10–1600 µm). The cell viability rate with the hydrogel was 95 and 100% with HUVECs and hMSCs, respectively. Incubating HUVECs with the biomaterial induced a 5-fold increase in TGF-β1 and a 3-fold increase in Complement C5a release. Furthermore, HUVEC supernatants obtained after incubation with the hydrogel induced a 2.5-fold increase in hMSC recruitment. The hydrogel induced a 3-fold increase both in hMSC ALP activity and BMP-2 secretion. Overall, the functionalized hydrogel enhanced the osteogenic potential by interacting with endothelial cells and hMSCs and represents a promising tool for bone tissue engineering.

Over the last two decades, calcium silicate-based materials have grown in popularity. As root canal sealers, these formulations have been extensively investigated and compared with conventional sealers, such as zinc oxide–eugenol and epoxy resin-based sealers, in in vitro studies that showed their promising properties, especially their biocompatibility, antimicrobial properties, and certain bioactivity. However, the consequence of their higher solubility is a matter of debate and still needs to be clarified, because it may affect their long-term sealing ability. Unlike conventional sealers, those sealers are hydraulic, and their setting is conditioned by the presence of humidity. Current evidence reveals that the properties of calcium silicate-based sealers vary depending on their formulation. To date, only a few short-term investigations addressed the clinical outcome of calcium silicate-based root canal sealers. Their use has been showed to be mainly based on practitioners’ clinical habits rather than manufacturers’ recommendations or available evidence. However, their particular behavior implies modifications of the clinical protocol used for conventional sealers. This narrative review aimed to discuss the properties of calcium silicate-based sealers and their clinical implications, and to propose rational indications for these sealers based on the current knowledge.