The purpose of this study was to elucidate behavior of human mesenchymal stem cells (hMSCs) on yttria stabilized tetragonal zirconia polycrystals (TZP) and commercial pure titanium (CpTi) with different surface topography. Mirror-polished (MS), sandblasted with 150-μm alumina (SB150) and SB150 acid-etched (SB150E) were prepared on TZP and CpTi. Proliferation, osteogenic differentiation of hMSCs was evaluated. The scanning electron microscopy showed that micro-and nano-topographies were created on both TZP and CpTi SB150E surfaces. The proliferation ability, ALP activity, expression of Runx2 on the both SB150E specimens was significantly higher than those on the other specimens. These results suggested that creation of micro-and nano-topographies on TZP and CpTi by blast and acid-etching may offer a promising method for enhancing the proliferation and differentiation of hMSCs in clinical application.

To clarify the influence of translucent tetragonal zirconia polycrystals (TZP) on wear properties of esthetic dental materials, twobody wear test was performed using translucent TZP as abrader specimen, and bovine tooth enamel (BTE), two resin composites including hybrid filler (CRH) and nano filler (CRN), two glass ceramics including leucite reinforced feldspar porcelain (POR) and lithium disilicate (LDC), or translucent TZP as substrate specimen. After the wear test, wear volume were determined from substrate specimen and surface roughness were measured from abrader specimen. In addition, Vickers hardness was measured and surface morphologies were observed after wear test using a scanning electron microscope. The wear volume of the esthetic dental material against translucent TZP was greater in glass ceramics (POR, LDC), smaller in resin composite (CRH, CRN) and BTE, and no wear in translucent TZP. Microstructures of the esthetic dental material may play a crucial role for wear behavior against translucent TZP.

No abstract

We examined chemical etching of the Ge surface assisted by single sheets of chemically modified graphene in O2-containing water. Three types of graphene sheets were used: graphene oxide (GO), hydrazine-reduced GO (hyd-rGO), and hydrothermally treated GO in an ammonia solution (amm-rGO). amm-rGO possessing pyridinic-N atoms produced the highest etching rates of the graphene used for all water temperatures tested. We propose that graphene sheets catalyze Ge oxidation underneath the sheets and that this phenomenon probably originates from the enhanced adsorption of O2 molecules in water at local defects, such as graphene edges and carbon atoms next to pyridinic-N, in the sheets. Because O2 adsorption is the initial step of either the oxygen reduction reaction or direct oxidation, it results in the formation of soluble GeO2 at the graphene/Ge interface, leaving etched hollows under the sheets. In addition, we combined graphene-assisted chemical etching with lithography by using photoresist to fabricate a trench pattern on Ge.

Here, we report a case of dental implant treatment involving computer-assisted surgery for bilateral agenesis of the maxillary lateral incisors. The patient was a 39-year-old woman with the chief complaint of functional and esthetic disturbance due to maxillary and mandibular malocclusion. The treatment plan comprised non-extraction comprehensive orthodontic treatment and prosthodontic treatment for space due to the absence of bilateral maxillary lateral incisors. A preliminary examination revealed that the mesiodistal spaces left by the absent bilateral maxillary lateral incisors were too narrow for implant placement (right, 5.49 mm; left, 5.51 mm). Additional orthodontic treatment increased these spaces to approximately 6 mm, the minimum required for implant placement if risk of damage to the adjacent teeth due to inaccuracies in directionality of drilling is to be avoided. For dental implant treatment with computer-assisted surgery, preoperative planning/simulation was performed using Simplant ver.12 software and a toothsupported surgical template fabricated using stereolithography. Two narrow-diameter implants were placed in a two-stage procedure. It was confirmed that there was sufficient distance between the implant fixtures and the roots of the adjacent teeth, together with no exposure of alveolar bone. Following a 4-month non-loading period, second-stage surgery and provisional restoration with a temporary screw-retained implant crown were performed. Cement-retained superstructures made of customized zirconia abutment and a zirconia-bonded ceramic crown were fitted as the final restoration. At 5 years after implant surgery, there were no complications, including inflammation of the peri-implant soft tissue and resorption of peri-implant bone. Computer-assisted implant surgery is useful in avoiding complications in bilateral agenesis of the maxillary lateral incisors when only a narrow mesiodistal space is available for implant placement.