Alloplasts are synthetic, inorganic, biocompatible bone substitutes that function as defect fillers to repair skeletal defects. The acceptance of these substitutes by host tissues is determined by the pore diameter and the porosity and inter-connectivity. This narrative review appraises recent developments, characterization, and biological performance of different synthetic materials for bone, periodontal, and dental tissue regeneration. They include calcium phosphate cements and their variants β-tricalcium phosphate (β-TCP) ceramics and biphasic calcium phosphates (hydroxyapatite (HA) and β-TCP ceramics), calcium sulfate, bioactive glasses and polymer-based bone substitutes which include variants of polycaprolactone. In summary, the search for synthetic bone substitutes remains elusive with calcium compounds providing the best synthetic substitute. The combination of calcium sulphate and β-TCP provides improved handling of the materials, dispensing with the need for a traditional membrane in guided bone regeneration. Evidence is supportive of improved angiogenesis at the recipient sites. One such product, (EthOss® Regeneration, Silesden UK) has won numerous awards internationally as a commercial success. Bioglasses and polymers, which have been used as medical devices, are still in the experimental stage for dental application. Polycaprolactone-TCP, one of the products in this category is currently undergoing further randomized clinical trials as a 3D socket preservation filler. These aforementioned products may have vast potential for substituting human/animal-based bone grafts.

Crouzon syndrome exhibits considerable phenotypic heterogeneity, in the aetiology of which genetics play an important role. mediates extracellular signals into cells and the mutations in the gene cause this syndrome occurrence. Activated signaling disrupts the balance of differentiation, cell proliferation, and apoptosis via its downstream signal pathways. However, very little is known about the cellular and molecular factors leading to severity of this phenotype. Revealing the molecular pathology of craniosynostosis will be a great value for genetic counselling, diagnosis, prognosis and early intervention programs. This mini-review summarizes the fundamental and recent scientific literature on genetic disorder of Crouzon syndrome and presents a graduated strategy for the genetic approach, diagnosis and the management of this complex craniofacial defect.

Our aim was to summarise current published evidence about the prognosis of various techniques of craniofacial distraction osteogenesis, particularly its indications, protocols, and complications. Published papers were acquired from online sources using the keywords "distraction osteogenesis", "Le Fort III", "monobloc", and "syndromic craniosynostosis" in combination with other keywords, such as "craniofacial deformity" and "midface". The search was confined to publications in English, and we followed the guidelines of the PRISMA statement. We found that deformity of the skull resulted mainly from Crouzon syndrome. Recently craniofacial distraction has been achieved by monobloc distraction osteogenesis using an external distraction device during childhood, while Le Fort III distraction osteogenesis was used in maturity. Craniofacial distraction was indicated primarily to correct increased intracranial pressure, exorbitism, and obstructive sleep apnoea in childhood, while midface hypoplasia was the main indication in maturity. Overall the most commonly reported complications were minor inflammatory reactions around the pins, and anticlockwise rotation when using external distraction systems. The mean amount of bony advancement was 12.3mm for an external device, 18.6mm for an internal device and 18.7mm when both external and internal devices were used. Treatment by craniofacial distraction must be validated by long-term studies as there adequate data are lacking, particularly about structural relapse and the assessment of function.

The need for bone graft alternatives has led to the development of numerous bone graft substitutes. Here, the authors have synthesized a biodegradable poly(caprolactone-trifumarate) (PCLTF) polymer solution that could be injected into any bony defect. This polymer solution was synthesized using polycaprolactone-triol and fumaryl chloride (FCl). PCLTF is a multiple-branching, unsaturated and cross-linkable in situ material. The surface microstructure of PCLTF was investigated using a field emission scanning electron microscope. The incorporation of double bonds originating from FCl into the poly(caprolactone) backbone was confirmed in the Fourier transform infrared spectra. The in vitro cytotoxic effects of PCLTF, its leachable extracts and degradation products were evaluated in direct and indirect contact tests against human oral fibroblasts. Cell viability was evaluated using the microculture tetrazolium assay and cytotoxicity evaluations of PCLTF were tested in accordance with ISO 10993-5 standards. The results showed that there was evidence of reasonable cell growth, good cell viability and intact cell morphology after exposure to PCLTF, its extracts and degradation products. There was no evidence of critical cytotoxic effects.

Sutural appositional bone formation corresponded with the amount of initial expansion to a point. When initial expansion was increased to 4 mm, sutural bone remodeling was disturbed and new bone formation was decreased. The most effective sutural expansion was achieved with 2.5 mm initial activation followed by 0.5 mm expansion/day for 7 days.

Bone tissue engineering offers high hopes in reconstructing bone defects that result from trauma, infection, tumors, and other conditions. However, there remains a need for novel scaffold materials that can effectively stimulate ossification with appropriate functional properties. Therefore, a novel injectable, biodegradable, and biocompatible scaffold made by incorporating modified poly(caprolactone trifumarate) (PCLTF) with embedded gelatin microparticles (GMPs) as porogen is developed. Specifically, in vitro and in vivo tests were carried out. For the latter, to determine the osteogenic ability of PCLTF-GMPs scaffolds, and to characterize bone-formation, these scaffolds were implanted into critical-sized defects of New Zealand white rabbit craniums. Field Emission Scanning Electron Microscope (FESEM) demonstrated cells of varying shapes attached to the scaffold surface in vitro. The PCLTF-GMPs demonstrated improved biocompatibility in vivo. Polyfluorochrome tracers detected bone growth occurring in the PCLTF-GMPs filled defects. By incorporating PCLTF with GMPs, we have fabricated a promising self-crosslinkable biocompatible and osteoconducive scaffold for bone tissue engineering.

Objectives: To assess and compare the quantity and the quality of the newly bone generated when using chitosan-based gel scaffold and osteoprotegerin-chitosan gel scaffold.Methods: A total of 18 critical-sized defects on New Zealand white rabbit craniums were created. In 12 defects, either chitosan gel or osteoprotegerin-chitosan gel was implanted the last six defects were kept unfilled as a control. Bone formation was examined at 6 and 12 weeks. Bone’s specimens were scanned using the High-resolution peripheral quantitative computed tomography. Histological and histomorphometric analysis were carried out to compare the volume and area of regenerated bone.Results: The results of the HR-pQCT showed that bone volume and densities in the osteoprotegerin-chitosan gel group were significantly higher than the chitosan gel and control groups whereas, the bone volume density in the chitosan gel group was significantly higher than the control group in both intervals time (p = 0.01, p = 000). No significant difference in bone volume between the chitosan gel and control groups (p = 0.506, p = 0.640) was observed. However, similar findings were shown in the histomorphometric analysis, with the highest new bone formation was observed in the OPG-chitosan gel group followed by the chitosan group. The mean percentage of new bone was greater at 12 weeks compared to 6 weeks in all groups.Conclusions: Chitosan-based gel demonstrated a significant bone quantity and quality compared to unfilled surgical defects. Consistently, osteoprotegerin enhanced the chitosan gel in bone regeneration.

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