Heat cure acrylic resin is the most widely used material for the fabrication of removable dentures even today. But due to its low fatigue strength and fracture resistance, the dentures tend to flex and can also fracture. With the advancement in nanoscience, nano-sized fillers were found to exhibit improved fracture resistance. Hence in this study both ZrO 2 (5%) & TiO 2 (1%) nanoparticles and its hybrid combination (2%) were used to comparatively evaluate the impact and flexural strengths of high impact acrylic resin. A total of 45 specimens were subjected to impact strength testing in an impact tester and flexural strength testing using three point bending test in a Universal testing machine respectively. The present study shows that hybrid reinforcement can be considered a better reinforcement option for enhancing the impact and flexural strengths of acrylic resin.
Aim:The aim of this study was to evaluate and compare flexural strength of repaired heat polymerized acrylic resin with zirconia oxide and aluminium oxide nanoparticles incorporated autopolymerized acrylic resin and to evaluate effect of butt and bevel joint design of repair with and without chemical surface treatment. Materials and Method: A total of 165 heat cure acrylic resin specimens were fabricated and divided into 3 main groups. Group A had 15 intact specimens whereas group B and group C were further divided into 5 subgroups depending on repair material, repair design and chemical surface treatment used. Each subgroup had 15 specimens. 7wt% zirconia oxide and 2wt% aluminium oxide nanoparticles used as reinforcement material into autopolymerized acrylic resin and compared with unreinforced autopolymerized resin used for repair. Butt and bevel joint designs and ethyl acetate as a chemical surface treatment used for repair of acrylic specimens. The specimens were subjected to flexural strength in a universal testing machine until specimens fractured and load values were recorded. Flexural strength wascalculated in MPa (Megapascal) and analysed using Independent t test, One Way ANOVA and Post hoc Tukey's test. Results: The flexural strength values obtained were highly significant for nanoparticles reinforced groups than unreinforced autopolymerized resin. Also zirconia oxide nanoparticles showed higher values than aluminium oxide nanoparticles. Similarly, repair with bevel joint design and with chemical surface treatment with ethyl acetate proved to be better.
Conclusion:Under the conditions of this study, 7wt% zirconia oxide and 2wt% aluminium oxide reinforced autopolymerized resin with bevel joint design and chemical surface treatment with ethyl acetate can be recommended for acrylic repair.
Objective: To compare and evaluate the bond strength of a fiber post cemented to different post space diameters using two commercially available resin cement. Methodology: 60 freshly extracted maxillary central incisor teeth with similar dimensions were selected and sectioned horizontally from CEJ. Endodontic treatment was done on all specimens and divided into two groups Group 1 and 2 (n=30) based on the post space diameter (0.9mm and 1.1mm). Each group was subdivided into two 1A, 1B, 2A, 2B (n=15) according to the cement used. Following the post space preparations, the canals were rinsed and dried. The adhesive resin cement was applied and posts were seated to full depth and excess cement was removed. After 24 hours specimens underwent 10,000 thermal cycles and preserved in saline solution. Specimens were mounted into universal testing machine and tensile force at a crosshead speed of 1 mm/ min was applied to the posts until they debond from the root canals. Data was analyzed using ANOVA test, Independent t test and Tukey HSD test. Result: The result shows increased bond strength in snug fit than passive fit. ie; more bond strength was observed in Group 1A (mean =26.75 KgF) and Group 1B (mean =15.72 KgF) where post size and peeso reamer drill size were same. When comparing two cements RELYX shows more bond strength (1A=26.75, 2A=14.82) than PANAVIA cement (1B=15.72, 2B=10.51). Conclusion: A post with snug fit post space preparation shows better resistance to pull out test than over prepared post space preparation. Cement RELYX U-200 shows higher tensile bond strength than PANAVIA-F cement.
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