engleski

Comparative Investigation of the Fracture Strengths of Crowns of Three Different Non-metal Materials

The demands of patients for high aesthetics during reconstructive prosthetic procedures accelerated the development of new materials and technology. Forces acting in the post-canine part of the dental arch amount to ≥ 500 N, and thus the material used for fabrication of the restoration must withstand such forces. The aim of this investigation was to study the resistance to fracture of three non- metal materials: 1. ceromer (Targis, Ivoclar-Vivadent), 2. ceromer reinforced with fibre reinforced composite (Targis/Vectris, Ivoclar- Vivadent), and 3. non-metal ceramic system (IPS Empress 2, Ivoclar- Vivadent). Eighteen identical crowns were fabricated from each type of material on a plaster model of a polished natural second lower premolar, according to the manufacturer’s instructions. The same tooth was used for fabrication of a metal model on which crowns were placed in the universal testing device ZWICK. The compressive plate was modified with a pin 7mm in diameter, which acted with force on the occlusal surface at an angle of 180˚. Force was applied up to the first sign of fracture, and the amount recorded. Half of the samples prior to the examination were thermocycled 1000x for 20 seconds at temperatures of 2˚C and 55˚C with 40 second intervals between immersion of the tempered sample. The mean value measured of the amount of force up to fracture for non-thermocycled samples amounted to 577.8 +/- 113.4 N for crowns of ceromer, 923.3+/- 229 N for crowns of ceromer and fibre reinforced composite, and 1208.9 +/- 161.8 N. for crowns of non-metal ceramic. Significant difference was determined by Mann-Whitney U test between all three materials (p < 0.05) for the amounts of loading up to fracture of the samples. Thermocycling did not significantly reduce the amount of force up to fracture of the sample. The investigation determined that all three materials are satisfactory for fabrication of permanent restorations in the area of the masticatory centre, as all withstand force greater than 500 N.

fracture strength, crowns, ceramic, fibre reinforced composites, ceromers.

nije evidentirano