A novel automatic mill of teeth and bone has been developed for bone engineering. A human frozen-tooth and/or a human frozen-bone block were put into the Zirconium oxide (ZrO 2 ) ceramics vessel of the machine, and crushed for 1 min with 20 salineice blocks (1 © 1 © 1 cm 3 /block) at 12000 rpm of ZrO 2 blade. The crushed granules were demineralized completely in 2% HNO 3 solution for 20 min, and rinsed in cold saline. We named each biomaterial after the acid treatment and washing, demineralized dentin matrices (DDM), demineralized bone matrices (DBM). Five wisdom teeth (total wet volume: 10.0 g) were crushed, decalcified, and lyophilized. The distribution of freeze-dried DDM granules was fine granules (0.51.0 mm: 0.27 g), moderate (1.02.0 mm: 0.46 g), and large (2.05.0 mm: 0.64 g). The fine granules of human DDM or DBM were implanted into the subcutaneous tissue of 4 week-old nude mice, and their tissue-inductive properties were estimated at 4 weeks after implantation histologically. The explanted samples were demineralized, embedded in paraffin, and sectioned. The specimens were stained with hematoxylin and eosin. We confirmed that DDM induced bone and cartilage independently, and DBM induced cartilage, bone and marrow at 4 weeks in the back skin of nude mice. These results indicated that our material preparation system by the novel mill with a vessel and a blade of ZrO 2 under ice-cooling maintained the bone-inducing activity of human dentin and bone.

Bioabsorbable and functionally graded apatite (fg-HAp) ceramics were designed using bovine bone by the calcination and partial dissolution-precipitation methods. The fg-HAp ceramics that were developed had gradual distributions of the degree of crystallinity and the grain size of single-phase hydroxyapatite from the surface layer of the pore wall to the bulk structure region. Calcination at 1073 K gave a specific surface area of 30 m2 x g-1 and porosities of 60-80%. The pore structure of the fg-HAp was classified into two regions: a macro-pore region (100-600 microm) originating from spongy bone and a micro-pore region (10-160 nm) related to body fluid permeation and blood permeability. By implantation in subcutaneous tissue of rat, it was confirmed that body fluid permeated the bulk region of the fg-HAp ceramics through the micro-pores. The volumetric populations occupied by body fluid were 60% at 4 weeks and 68% at 8 weeks in the ceramics explants, indicating drastic bioabsorption, although the body fluid was found to be immunopositive for an albumin as the main serum protein in blood. On the fg-HAp ceramics developed here, the bioabsorption rate could be controlled by careful selection of the calcination temperature. These ceramics can be applied as new biomimetic ceramics exhibiting surface and bulk degradations and cellular absorption by giant cells.

HighlightsHigh-dose prostate IMRT was well tolerated in terms of long-term GU toxicities.Hematuria was the most common long-term GU toxicity after high-dose IMRT.Bladder neck dose–volume data were significantly associated with hematuria.

Commercial products of hydroxyapatite (HAp) were easily modified to obtain partially-dissolved and precipitated HAp (PDPHAp) ceramics by the specific dissolution precipitation technique, which involved a stirring of 300 rpm at 298 K in 1.7 3.4 © 10 ¹2 N-HNO 3 solutions (50 cm 3 ) containing Ca 2+ and PO 4 3¹ ions or/and a supersonic treatment at 120 W and 38 kHz in the same solutions. The dissolution efficiency of porous HAp products by the supersonic treatment, which was much higher than that by stirring, drastically increased with time, depending on the porosity of ceramics and the concentration of HNO 3 solution. For even dense HAp products, enhancement of micro-pores and propagation of micro-cracks were recognized by the supersonic treatment for 20 min. After the stirring of 30 min and the subsequently supersonic treatment of 25 min, HAp nano-crystals with the composition ratio (Ca/P) of 1.64 1.66 were successfully precipitated on the pore wall surface in the macro-pores and micropores of the ceramics at 298 K and pH 9 10. The PDP-HAp ceramics that gave macro-pore sizes of 50 200 µm, porosities of 85 90%, and specific surface areas of 1 2 m 2 ·g ¹1 , were implanted into the bone defects at the medial condyle of femur in Japanese white rabbits. At 8 and 16 weeks after the implantation, the PDP-HAp ceramics exhibited more excellent bio-absorption and tissue-affinity than commercial HAp products because of smooth body-fluid-permeation and effective surface nature for celladsorption. The PDP-HAp developed can be applied as one of bioactive scaffolds with good bio-absorption and osteoconduction characteristics for bone-regeneration therapy.