• The Journal of Advanced Prosthodontics
• /
• v.10 no.2
• /
• pp.79-84
• /
• 2018

PURPOSE. All-ceramic restorations required extensive tooth preparation. The purpose of this in vitro study was to investigate a minimally invasive preparation and thickness of monolithic zirconia crowns, which would provide sufficient mechanical endurance and strength. MATERIALS AND METHODS. Crowns with thickness of 0.2 mm (group 0.2, n=32) or of 0.5 mm (group 0.5, n=32) were milled from zirconia and fixed with resin-based adhesives (groups 0.2A, 0.5A) or zinc phosphate cements (groups 0.2C, 0.5C). Half of the samples in each subgroup (n=8) underwent thermal cycling and mechanical loading (TCML)(TC: $5^{\circ}C$ and $55^{\circ}C$, $2{\times}3,000cycles$, 2 min/cycle; ML: 50 N, $1.2{\times}10^6cycles$), while the other samples were stored in water ($37^{\circ}C/24h$). Survival rates were compared (Kaplan-Maier). The specimens surviving TCML were loaded to fracture and the maximal fracture force was determined (ANOVA; Bonferroni; ${\alpha}=.05$). The fracture mode was analyzed. RESULTS. In both 0.5 groups, all crowns survived TCML, and the comparison of fracture strength among crowns with and without TCML showed no significant difference (P=.628). Four crowns in group 0.2A and all of the crowns in group 0.2C failed during TCML. The fracture strength after 24 hours of the cemented 0.2 mm-thick crowns was significantly lower than that of adhesive bonded crowns. All cemented crowns provided fracture in the crown, while about 80% of the adhesively bonded crowns fractured through crown and die. CONCLUSION. 0.5 mm thick monolithic crowns possessed sufficient strength to endure physiologic performance, regardless of the type of cementation. Fracture strength of the 0.2 mm cemented crowns was too low for clinical application.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.5
• /
• pp.1936-1942
• /
• 2010

To examine the effect of overdosed functional food in liver-injured patients, we tried to investigate the dose effect of Allium sativum L. (also called garlic) extract on rats with CCl4-induced liver damage, by comparatively examinating the hepatic function of each group. 42 male Sprague-Dawley rats were selected and divided equally (n=7) into normal, control, positive control, and three experimental subgroups (E1, E2 and E3), respectively. For each kg of body weight, hepatic injury was induced by intraperitoneal administration of $0.5\;m{\ell}$ (0.20 g/kg/day) $CCl_4$, which was diluted in equal amount of olive oil, once a day on every other day for total 5 times. Hot water extraction was performed using domestically cultivated organic garlics, and the obtained extract was injected by sonde, once daily during 4 weeks, to each experimental subgroups by different dosage of 0.35 g/kg(E1), 0.70 g/kg(E2), 1.40 g/kg(E3), respectively. Results showed that the injection of garlic extract positively influenced the physiological activation which lowered the oxidative stress, changed the toxicity, and functionally improved the hepatic condition. Comparing the dose effect between the three experimental subgroups (E1, E2, E3), results of the maximal-dosed subgroup (E3) showed less significance compared with the lower-dosed subgroups(E1 and E2), which seems to resulted from the (increased) toxicity of garlic.