著者

三嶋 直之 富田 達洋 松原 秀憲 簗瀬 武史 吉成 正雄

出版者

公益社団法人 日本口腔インプラント学会

雑誌

日本口腔インプラント学会誌 (ISSN:09146695)

巻号頁・発行日

vol.27, no.4, pp.541-548, 2014-12-31 (Released:2015-02-01)

参考文献数

25

---

The aim of this study was to examine the possibility of repeated heat-pressing of pressable glass-ceramic by evaluating the influence of repeated heat-pressing on mechanical properties, surface characteristics and dimensional accuracy. A commercially available pressable glass-ceramic system (IPS e.max Press, Ivoclar Vivadent, Liechtenstein) was selected in this study. Disc samples with 12.5 mm in diameter and 1.3 mm in thickness were heat-pressed and used as the first heat-pressing specimens. Sprue and button parts of the first heat-pressed specimens were retrieved, and they were used to construct the second heat-pressed specimens. The third heat-pressing groups were constructed in just the same way as the second heat-pressing groups. All the heat-pressing procedures were performed according to the manufacturers' instructions. After the arithmetic mean surface roughness (Ra) of pressed specimens was measured, a biaxial flexural strength (BFS) of disc specimens was measured using a universal testing machine. Surface hardness, optical microscopic and scanning electron microscopic observations were carried out. Surface characteristics were examined with X-ray diffractometry (XRD) and electron probe microanalysis (EPMA). The dimensional accuracy of a heat-pressed full crown was also evaluated. The Ra values ranged from 4.0-4.3 μm of all heat-pressing groups. The BFS values obtained were 346±29 MPa, 312±24 MPa and 305±20 MPa for the first, second and third heat-pressing group, respectively. The third heatpressing group showed a lower BFS mean than the first heat-pressing group (p=0.038). Surface hardness showed around 540 Hv in all heat-pressing groups. Microscopic observations revealed that small amounts of porosity were observed in all heat-pressing groups with no differences among the number of heat-pressings, and that the apparent lithium disilicate crystals were confirmed by XRD. A compositional change was not recognized in all heatpressing specimens by EPMA. The dimensional change of all heat-pressed full crowns ranged from +0.16-0.19% with no differences among the number of heat-pressings. These results demonstrated that the repeated heatpressing of pressable glass-ceramics used in this study was available with a slight decrease in strength and no differences in surface characteristics and dimensional accuracy.

著者

米澤 幸平 松原 秀憲 米澤 嘉朗

出版者

中部日本整形外科災害外科学会

雑誌

中部日本整形外科災害外科学会雑誌 (ISSN:00089443)

巻号頁・発行日

vol.61, no.1, pp.115-116, 2018