ABSTRACT
PURPOSE: To investigate the void parameters within the resin cements used for fiber post cementation by micro-CT (µCT) and regional push-out bonding strength. MATERIALS AND METHODS: Twenty-one, single and round shaped roots were enlarged with a low-speed drill following by endodontic treatment. The roots were divided into three groups (n=7) and fiber posts were cemented with Maxcem Elite, Multilink N and Superbond C&B resin cements. Specimens were scanned using µCT scanner at resolution of 13.7 µm. The number, area, and volume of voids between dentin and post were evaluated. A method of analysis based on the post segmentation was used, and coronal, middle and apical thirds considered separately. After the µCT analysis, roots were embedded in epoxy resin and sectioned into 2 mm thick slices (63 sections in total). Push-out testing was performed with universal testing device at 0.5 mm/min cross-head speed. Data were analyzed with Kruskal–Wallis and Mann–Whitney U tests (α=.05). RESULTS: Overall, significant differences between the resin cements and the post level were observed in the void number, area, and volume (P.05). CONCLUSION: µCT proved to be a powerful non-destructive 3D analysis tool for visualizing the void parameters. Multilink N had the lowest void parameters. When efficiency of all cements was evaluated, direct relationship between the post region and push-out bonding strength was not observed.
Subject(s)
Cementation , Dentin , Resin CementsABSTRACT
PURPOSE: To evaluate the cytotoxicity of temporary luting cements on bovine dental pulp-derived cells (bDPCs). MATERIALS AND METHODS: Four different temporary cements were tested: Rely X Temp E (3M ESPE), Ultratemp (Ultradent), GC Fuji Temp (GC), and Rely X Temp NE (3M ESPE). The materials were prepared as discs and incubated in Dulbecco's modified eagle's culture medium (DMEM) for 72 hours according to ISO 10993-5. A real-time cell analyzer was used to determine cell vitality. After seeding 200 microL of the cell suspensions into the wells of a 96-well plate, the bDPCs were cured with bioactive components released by the test materials and observed every 15 minutes for 98 hours. One-way ANOVA and Tukey-Kramer tests were used to analyze the results of the proliferation experiments. RESULTS: All tested temporary cements showed significant decreases in the bDPCs index. Rely X Temp E, GC Fuji Temp, and Rely X Temp NE were severely toxic at both time points (24 and 72 hours) (P.05); however, the cell viability was significantly reduced at 72 hours (P<.001). Light and scanning electron microscopy examination confirmed these results. CONCLUSION: The cytotoxic effects of temporary cements on pulpal tissue should be evaluated when choosing cement for luting provisional restorations.
Subject(s)
Cell Survival , Microscopy, Electron, Scanning , SuspensionsABSTRACT
PURPOSE: The aim of this study was to evaluate the effects of repeated porcelain firing process on the corrosion rates of the dental alloys. MATERIALS AND METHODS: Cr-Co, Cr-Ni and Pd-Ag alloys were used for this study. Each metal supported porcelain consisted of 30 specimens of 10 for 7, 9 and 11 firing each. Disc-shaped specimens 10 mm diameter and 3 mm thickness were formed by melting alloys with a propane-oxygen flame and casted with a centrifuge casting machine and then with the porcelain veneer fired onto the metal alloys. Corrosion tests were performed in quintuplicate for each alloy (after repeated porcelain firing) in Fusayama artificial saliva solution (pH = 5) in a low thermal-expansion borosilicate glass cell. Tamhane and Sheffe test was used to compare corrosion differences in the results after repeated firings and among 7, 9 and 11 firing for each alloy. The probability level for statistical significance was set at alpha=0.05. RESULTS: The corrosion resistance was higher (30 mV), in case of 7 times firing (Commercial). On the other hand, it was lower in case of 11 times firing (5 mV) (P<.05). CONCLUSION: Repeated firings decreased corrosion resistance of Pd-Ag, Cr-Co and Cr-Ni alloys. The Pd-Ag alloy exhibited little corrosion in in vitro tests. The Cr-Ni alloy exhibited higher corrosion resistance than Cr-Co alloys in in vitro tests.