Craniofacial sutures house multipotent stem cells
Zhao H, Feng J, Ho TV, Grimes W, Urata M, Chai Y. The suture provides a niche for mesenchymal stem cells of craniofacial bones. Nat Cell Biol 2015; 17:386-96
Craniosynostosis is a condition where sutures fail to remain open and cause complications such as increased intracranial pressure, dysmorphism, neuro-development disruption, and mental retardation. The authors of this study identified perivascular mesenchymal stem cells (MSCs) cells known as Gli1+ in the unfused suture using a mouse model in which the suture remained unfused throughout their lives. The MSCs were tagged and transplanted into newborn mice and observed as they grew. The authors investigated their reparative ability in comparison with control mice. They found that Gli1+ cells are specifically distributed in all craniofacial sutures, but not in the periosteal area and not where osteocytes are present. Mostly in adult mice, MSCs were found in the middle of the sutures where there was still activity. The authors also found MSCs in the bone marrow, although in minor amounts. According to their findings, MSCs gave rise to osteogenic fronts, osteocytes, and dura. The results suggested that Gli1+ cells have a multipotent property but were weaker in differentiation ability when harvested from marrow spaces than from sutures, suggesting that the stem cell property is responsible for all turnovers of calvarian bones. Their findings included Gli1+ as primary cells in reparation of injury; this contradicts the previously proposed concept that progenitor cells for bone repair were in the periosteum. Last, the authors found that ablation of Gli1+ cells leads to cessation of growth, osteoporosis, diminished reparative ability, and craniosynostosis. The authors provided new information on MSCs of the craniofacial bones. They determined that Gli1+ cells in the sutures are indispensable for calvarial growth and injury healing. Their impact on craniofacial bone growth is immense and may lead to better understanding of craniosynostosis and other craniofacial disorders.
Reviewed by Ioannis Tsolakis
Antibacterial and biocompatibility of a nanoparticulate silver-titanium dioxide bracket coating
Zhang R, Zhang W, Bai X, Song X, Wang C, Gao X, et al. Discussion on the development of nano Ag/TiO 2 coating bracket and its antibacterial property and biocompatibility in orthodontic treatment. Pak J Pharm Sci 2015; 28(2 Suppl):807-10
Compliance with suggested oral hygiene instructions during treatment is a constant challenge for orthodontists. The oral hygiene of our orthodontic patients has a significant impact on their overall oral health and esthetics. This study discussed the development of a nanoparticulate silver-titanium dioxide (nano Ag/TiO 2 ) bracket surface coating and examined its antibacterial and biocompatibility properties. Surface coatings of titanium dioxide (TiO 2 ) and Ag/TiO 2 nanoparticulates on brackets were completed by the spin-on deposition method. The antibacterial properties of the nano TiO 2 and Ag/TiO 2 coatings were tested on the common oral bacteria in the oral cavity ( S mutans , S sanguis , A actinomycetemcomitans , F nucleatum , P gingivalis , and P intermedia ). Then the bonding strengths of the nano TiO 2 and nano Ag/TiO 2 coatings were evaluated via scratch tests. The rough surface of the bracket is the initial factor of plaque adhesion. These surfaces can provide a shielding effect to prevent the flow of saliva, among other things, in removing plaque. Scanning electron microscope observation of the surface appearance of the nano Ag/TiO 2 coating showed a rigorous organizational structure and an even particle distribution. The antibacterial effect of the nano Ag/TiO 2 coating for the common bacteria in the oral cavity after 20 minutes was observed at 79% after 20 minutes at a bacterial culture broth concentration of 1 × 10 6 colony-forming units per milliliter, and exhibited complete kill after 60 minutes. This discussion highlights the impact that nanotechnology can provide for orthodontic material fabrication.
Reviewed by Keith Payton