Discussion
critical-sized defects, horizontal bone loss, ®, infections, implant deterioration, tooth, bone defects
BONE LOSS, ADVERSE REACTION, INFECTIONS, COMPLICATIONS
This is the first-in-human study of DEXGEL Bone on safety and efficacy. No local or systemic complications or infections were identified, and none of the participants were excluded from the study. A synthetic bone substitute, BL® (control), was compared to its hydrogel-reinforced version, DEXGEL Bone (test), in the preservation of the alveolar ridge dimensions following tooth extraction. Six months after exodonty and grafting, CT scans showed healed bone defects in both groups, suitable for bone sample collection and dental implant placement. The implants were eventually loaded with prostheses, generally 13 weeks post-implantation. Major outcomes of this study include handling properties, safety validation, assessment of bone quantity and quality, and primary stability of implant.From a commercial point of view, an extended shelf-life is important for any product. However, extended stability studies on hydrogels for biomedical applications are scarce in literature. The reticulation of DEXGEL is driven by covalent interactions between ODEX aldehydes and ADH amines, and gelation time can be manipulated to vary between a few seconds to several hours, depending on ODEX and ADH concentrations or on the oxidation degree [Stability and conformability are of particular importance, to avoid the release or migration of particles, assess difficult sites, mold to the defect, and provide a reproducible and homogeneous mixing procedure convenient to the surgeon. Synthetic bone substitutes are now available in different forms, though with some shortcomings on handling properties. For instance, granules can migrate out of the defect during and after surgery; microporous blocks may be difficult to fit within the defect; and cement paste might set too fast and, similar to putty, can be poorly injectable [Clinically, no complications were observed and all participants healed normally. Histologically, both test and control groups showed good integration of grafting material into newly formed bone and were biologically compatible with the host tissues, showing no signs of adverse reaction. Photomicrographs confirmed the formation of vascularized mature bone and soft tissue matrix, confirming the osteoconductive character of both test and control groups. A considerably lower number of granules were visible in the test group, interspaced by a thicker new bone formation, as compared to the control group. In accordance with histologic observations, histomorphometric examination showed DEXGEL-accelerated BL® reabsorption without compromising total bone growth, as we have previously shown in the regeneration of critical-sized defects in a goat model [Ideally, scaffold materials should degrade synchronously as new bone ingrowth takes place, without loss of mechanical support. As the bone regeneration process takes place, BL® is also resorbed in a slow and controlled manner, contributing to the natural remodeling of the bone [Despite the favorable biodegradability, the use of polymeric bone grafters is restricted by limitations related to acidic degradation products that may accelerate implant deterioration and induce inflammatory reactions with negative implications for tissue repair [The success of dental implant placement relies on both the alveolar bone volume and density. The first may allow implant placement in the three-dimensionally correct position or, on the contrary, prevent its placement due to inadequate bone dimensions. In this latter case, a second-regeneration treatment simultaneously with implant placement may be considered. The second may essentially influence the primary stability of the implant, its osseointegration, and the timing of prostheses loading. Human studies on dimensional changes of undisturbed alveolar natural healing have reported horizontal bone loss of 29–63% and vertical bone loss of 11–22% at 6 months post-extraction [ISQ can ultimately determine whether or not the implant will withstand the impact of a provisional or a final restauration, and the subsequent mechanical impact from masticatory forces when integrated in the overall dentition. ISQ is, therefore, important for decision-making during implant treatment and follow-up [In this study, we used the 250–500-µm spherical BL® which has shown to induce a slightly faster bone regeneration than 500–1000 µm [