Bioengineered dental and bone structures for jaw repair
Modern methods of plastic reconstruction of the jaw consist of many stages. First, surgeons repair the damage to the bone, into which a dental implant is subsequently implanted. This procedure is quite lengthy and painful, and the desired aesthetic and functional result is achieved only if both stages are successful. Despite the improvement in the quality of life of patients, long-term prognosis of the implant condition is often impossible, especially in young patients whose jaws continue to grow.
The possibility of creating bioengineered combined bone and dental implants that would grow together with the surrounding tissues would significantly improve clinical results and make life easier for patients.
Scientists at Tufts University and other research institutions in Boston (Massachusetts), working under the guidance of Professor Pamela C. Yelick, tested the possibility of simultaneous reconstruction of the jaw bone and teeth. In 2002, the authors for the first time announced the successful regeneration of dental crowns from cultured dental germ cells sown in biodegradable scaffolds that were implanted in rats. The crowns of the teeth that grew at the same time practically did not differ in structure from normal ones.
After that, combining this method of tooth restoration and the increasingly used method of growing bone grafts using a skeleton seeded with bone marrow stem cells, scientists created hybrid tooth-bone structures. These structures were implanted into the omentaries (tissues connecting the structures of the abdominal cavity) of rats. In this case, not only the crowns of the teeth were formed, but also the dental roots and the surrounding alveolar bone. However, the conditions of the abdominal cavity differ significantly from the conditions of the oral cavity, therefore, in their latest work, the authors changed the methodology of conducting experiments.
Osteoblasts grown from bone marrow stem cells of female Yucatan minisweeds were sown in a biodegradable frame and cultured in a bioreactor for two weeks. Dental structures were created from the enamel organ of the dental rudiment (dental epithelial cells) and pulp (dental mesenchymal cells) of the second molars of the same mini-larvae. These cells were seeded with appropriate biodegradable structures, which were connected with a bioengineered bone structure using suture material and the entire complex was implanted into the right jaw of the pig that served as a cell donor. Control structures consisting of structures that do not contain cells of dental structures and seeded only with osteoblasts were implanted into the left jaw of animals.
After 12 or 20 weeks, the implants were removed and analyzed using high-resolution volumetric computed tomography and histological analysis. On the images obtained during tomography, the presence of dense radiopaque tissues similar to dentin and/or tooth enamel, surrounded by mineralized tissue, with a density corresponding to bone density, was recorded. Only mineralized bone tissue was detected at the site of control implants. The degree of mineralization of the implants was higher 20 than 12 weeks after the procedure. Currently, to confirm the results, the researchers are conducting a detailed histological and immunohistochemical analysis of the samples.
The authors believe that their preliminary results demonstrate the reality of creating bioengineered structures for the restoration of defects in facial bones and teeth. They continue to work on improving the model in order to improve the formation of alveoli, the direction of bone regeneration, the development of the dental root and teething.
The results of the work (W. Zhang et al. “Reconstructing Mandibular Defects with Autologous Bioengineered Tooth and Bone”) the authors reported at the 37th Annual Congress of the American Dental Research Association on April 5, 2008.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
07.04.2008