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In Vitro Examination of Polyethylen-Fiber-Reinforced-Composite-Bridges.C. KOLBECK*, M. ROSENTRITT, M. BEHR, R. LANG, G. HANDEL(Department of Prosthetic Dentistry, University of Regensburg, Germany)

#1572

Connect/belleGlass: buccal Vectris/Targis: buccal

Vectris/Targis: occlusalConnect/belleGlass: occlusalConnect/belleGlass Vectris/Targis

Introduction: In order to avoid unsatisfactory shine through or other negative effects caused by metal restorations, tooth-colored and translucent materials for dentalrestorations are looked for. In posterior teeth areas these materials have to withstand high mechanical loading. In vitro tests as well as clinical experiences made onthe fibreglass-reinforced-composite-system Vectris/Targis (Ivoclar) encourage further investigation and clinical use of fibre-reinforced-composite-systems in anterior as well as in posterior teeth. The aim of this in vitro study was to examine the fracture strength of adhesively luted three-unit posterior bridges made of the new polyethy-len-fibre-reinforced-composite-system ConnectTM/belleGlassTMHP. This tooth-colored material combination developed by Belle de St. Claire, USA consists of the poly-ethylen-fibre-material ConnectTM and the veneer material belle GlassTMHP, a microhybrid composite.

Materials and Methods: The roots offreshly extracted human third molars werecovered with a 1 mm thick polyether layer(Impregum, ESPE) for simulation of thehuman periodontium. The teeth then werepositioned in PMMA resin (Palapress, Kul-zer) at a distance of 10 mm to represent amolar gap. Preparation was performed re-sulting in a 1mm deep shoulder preparationwith one finishing line in dentin the other inenamel. 8 three-unit posterior bridges weremade of the Vectris/Targis-system, 8 of theConnectTM/belleGlassTMHP-system followingmanufacturers instructions. The bridgeswere adhesively luted using the systemSyntac/Variolink II (Vivadent, Liechten-stein). After thermal cycling and mechani-cal loading (TCML) in an artificial oral en-vironment the bridges were loaded to frac-ture in the universal test machine (Zwick,Germany). The bridges were examined ra-diologically and optically before and afterfailure to describe the different forms offracture. Median and percentiles (25/75%)were calculated. Statistical analysis wasperformed using Mann-Whitney-U- andKruskal-Wallis-Test. Significance was setto a level of p = 0.05.

Results:

Conclusion: Assuming maximum chewing forces of 300 - 500 N on posterior teeth, both systems showed sufficient fracture strength. Themedian (25/75% percentiles) fracture force of the ConnectTM/belleGlassTMHP-system was found to be 830 (640/980) N. The results for theVectris/Targis-system of 1470 (1620/1440) N showed this fracture force to be significantly higher (p=0.0108) then the one of the testedpolyethylen-fibre-reinforced-composite-system. Optical and radiological examination represented no discernible damage at the ConnectTM-respectively Vectris-framework. Failure probably can be attributed to fractures of the facing material off the frameworks. The resultsencourage further investigation and clinical use of both tested systems.

Base Mould Preparation Adhesive Luting TCML Universal Test Machine

1.2 x 106 x 50 N

6000x5°C55°C2min each

Manufacture of ConnectTM/belleGlassTM-bridges Manufacture of Vectris/Targis-bridges

Vectris-single 45°

Vectris-pontic 0°

Vectris-frame 90°

third molars10mm gap

1 mm shoulder1 in dentin1 in enamel

Syntac/Variolink II

1mm/min

12.5 mmtin foil

p = 0.0108