HPD Research Day | February 16, 2018

10 Marder Auditorium 11:45 a.m. – 12:15 p.m. Comparison of Pre-Cleaning Methods on the Sterilization and Microstructure of Dental Diamond Burs Zeenat Khan, DDS, PG-Prosthodontics, College of Dental Medicine, Nova Southeastern University Umadevi Kandalam, Ph.D., Assistant Professor, College of Dental Medicine, Nova Southeastern University Jeffrey Y. Thompson, Ph.D., Professor, College of Dental Medicine, Nova Southeastern University Sharon C. Siegel, DDS, Associate Professor, College of Dental Medicine, Nova Southeastern University Objective. This study compared bacterial growth after autoclaving contaminated diamond burs pre-cleaned by four different methods. Background. Studies show autoclaving to be the most effective method to sterilize dental instruments including burs. It has been reported that autoclaving of diamond burs is not 100% effective. National guidelines require pre-cleaning prior to autoclaving but no studies compare pre-cleaning methods on sterilizing diamond burs. Methods. IRB approval was granted(2017-299). Twelve medium grit multiple-use diamond burs were used for testing of four pre-cleaning groups and 3 control groups for a total of 96 burs. These groups included positive controls, negative controls, single-use diamond controls and the four research groups. Each bur was contaminated by preparing one tooth per patient. In groups of 12, the burs were pre-cleaned by either manual scrubbing, ultrasonic, diamond cleaning stone, or steam cleaning. The pre-cleaned burs were autoclaved at 270° F for 35 minutes. They were placed in sterile tubes filled with Brain Heart Infusion broth under aseptic technique at 37° C for 72 hours. The presence of bacterial growth was assessed by measuring the absorbance values. Microstructure analysis was performed using Scanning Electron Microscopy (SEM). Results. After autoclaving, no bacterial growth was observed in any group. SEM studies demonstrated thatdiamond burs pre-cleaned by manual scrubbing removed the diamond chips. Conclusions. All pre-cleaning methods were equally effective in showing complete sterilization of diamond burs. Manual scrubbing of diamond burs is not recommended since it results in a compromised instrument. Grant. Funded by the HPD Research Grant (035067). Marder Auditorium 2:15 – 2:45 p.m. A Novel Cell Therapy via Direct Reprogramming of Human Fibroblasts into Functional Osteoblasts for Bone Regeneration Kenta Yamamoto, Ph.D., College of Dental Medicine, Nova Southeastern University Toshihisa Kawai, DDS, Ph.D., College of Dental Medicine, Nova Southeastern University Objective. Osteoblasts (OBs) play a central role in osteogenesis. It is thought that autologous somatic stem cells or iPS cells represents the sufficiently efficient bone regenerative therapy. This approach is, however, limited by the number of available authentic stem cells as well as cost- and time-consuming procedures. In this study, we developed a novel method of directly reprogramming human fibroblasts which are abundantly available from patients into functional OBs. Methods. Normal human fibroblasts were transfected with a panel of selected genes using retroviral vectors or polycistronic plasmid vector, and then cultured in osteogenic medium. The resultant cells were tested in vitro for expressions of OB-specific genes, the production of calcified bone matrix, and the epigenetic status of the cells. To assess in vivo function, the reprogramed OBs were transplanted to the bone defect generated in immune-deficient mice. Results. Gene-transfection of fibroblasts using retroviral vector induced osteocalcin- and ALP-positive OB-like cells which produced mineralized bone matrix at high efficiency, while polycistronic plasmid vector showed modest efficiency. Such reprogrammed OB-like cells demonstrated distinctly different methylation status from original fibroblasts, while displaying the gene-expression profile similar to normal OBs. Directly reprogrammed OBs, further, facilitated sufficient bone regeneration in vivo. These results suggest the direct transformation of fibroblasts can generate functional OBs. Conclusion. We developed a novel technique to directly reprogram human somatic cells, i.e., fibroblasts, into functional OBs by transfection with defined genes, offering an alternative cell therapy for bone regeneration in some patients, e.g. elderlies, who have limited number of stem cells. Grants. NSU HPD grant, Osteology foundation research grant.