@article{oai:mdu.repo.nii.ac.jp:00001819,
 author = {竹内, 賢 and 河瀬, 雄治 and 永沢, 栄},
 issue = {2},
 journal = {松本歯学},
 month = {Dec},
 note = {application/pdf, Strain due to slight misfit between an implant and superstructure increases the risk of implant fracture and resorption of supporting bone. Therefore, the accuracy of the fit of superstructures should be high. The fit accuracy of superstructures fabricated by casting is markedly affected by investment procedures and conditions. Therefore, it is extremely important to clarify changes in the setting and thermal expansion of investments with changes in the conditions of their use. We investigated the relationship between the time course of the water content of quick− heating gypsum−bonded investments after investment and the fit accuracy of castings, evaluated improvement in the casting accuracy, and obtained the following results : 1. The water content of quick−heating gypsum−bonded investments decreases with time after investment. 2. A decrease in the water content of investments reduces the fit accuracy of castings. 3. Water absorption by investments a long time after investment can improve the fit accuracy of castings. 4. The decrease in the fit accuracy of castings due to a reduction in the water content of investment materials is due to the early arrival of the investment temperature at the critical temperature for setting expansion. 5. The setting expansion of investments becomes maximal at a temperature of about 55°C. 6. When castings are preheated for 20 minutes in a hot water tank (55°C), practical application and a very accurate fit can be achieved.},
 pages = {93--99},
 title = {石膏系急速加熱型埋没材の埋没後経過時間と加熱温度コントロールによる鋳造精度の向上},
 volume = {39},
 year = {2013}
}