Yukito Hirose

Effect of low intensity pulsed ultrasound stimulation on sinus augmentation in rabbits

Objectives The objective of the present study was to evaluate the efficacy of low intensity pulsed ultrasound stimulation (LIPUS) and to determine the optimal frequency for enhancing bone regeneration in sinus augmentation using a rabbit model. Material and methods Thirty male rabbits underwent sinus augmentation. Two rectangular nasal bone windows were outlined bilaterally. LIPUS was applied at two different frequencies (1 MHz and 3 MHz) on experimental sites daily for 2, 4 and 8 weeks. Each histological area of the experimental and control sites was divided into upper and lower parts from the parietal region to a depth of 5 mm. Each area of new bone was measured. Results At 2, 4 and 8 weeks, the experimental sites in the 1 MHz group exhibited significantly more new bone growth than the control sites in both the upper and lower parts. When the upper and lower parts of each area were measured in combination there was a statistical difference between the test and control sites in the 1 MHz group at 2, 4 and 8 weeks; however, there were no statistical differences between the test and control sites in the 3 MHz group. Conclusions The results suggest that clinical application of LIPUS for sinus augmentation may promote new bone formation, and that the effect of LIPUS for sinus augmentation at a frequency of 1 MHz was greater than at 3 MHz until 8 weeks after sinus augmentation.

Simultaneous Implantation of Dental Implants and Autogenous Human Dentin

In our previous clinical study, autogenous demineralized dentin matrices (DDM) prepared from the functional vital teeth (#38, #41) of thirty-five-year-old female were grafted on the bone defect, using newly developed mill, and then received to the host without troubles. In this study, we implanted the human tooth dentin adjusted previously and the dental implants into the regions of missing tooth simultaneously. Fifty-seven-year-old female presented with missing teeth (#35-#37, #45-#47). First, a non-functional vital tooth (#18) were extracted and cryopreserved immediately. 11 months after extraction, the tooth was crushed by newly developed auto-crash mill using ZrO2 vessel and ZrO2 blade for 1 minute. The crushed granules were demineralized completely in 2% HNO3 solution, rinsed in cold distilled water and lyophilized (granule size: 0.5-2.0mm). The bacteria-free of the DDM were confirmed by the bacteriological examination before use. Drilling of the prospective implant beds were then performed according to the manufacture’s protocol and a screw-type rough surface implants (Nobel Biocare® Mk III) were placed. The adjusted DDM granules were implanted into the bone defect (#45). There are no postoperative complications at 3 years after implantation. This case indicates that the preserved autogenous DDM can be used as collagenous biomaterials with osteoinductive potency.

Human Dentin Transplantation for Bone Engineering

The aims of this study are to confirm the capacity of hard tissue induction by human demineralized dentin matrics (DDM) and calcified dentin matrics (CDM) in subcutaneous tissues of nude mice, and to report a human pioneering trial following the autotransplantation of DDM for bone augmentation in a case of the atrophied upper jaw. Human DDM and CDM particles were prepared from adult, extracted vital teeth, and were implanted into the subcutaneous tissues of 4-week-old nude mice. DDM induced bone and cartilage independently at 4 weeks after implantation, while CDM did not induce a hard tissue formation. Autogenous DDM prepared from the non-functional second molar of a 58-year-old female were grafted on the atrophied jaw and received to the host. Human dentin can be recycled as autogenous biomaterials for local bone engineering.