M. BEHR *, M. ROSENTRITT, C. KOLBECK, R. LANG, G. HANDEL.
(Department of Prosthetic Dentistry, University of Regensburg, Germany)
The damage of composite crowns may cause the replacement of a fixed partial denture (FPD), but intraoral repair methods can help to provide this loss. The aim of this in vitro study was to examine the fracture strength of an intraoral repair method of an adhesively luted glass-fiber-reinforced composite crown (Conquest Sculpture/FibreKor, Jeneric Pentron). Shear bond strengths (SBS) of the veneering composite (Conquest Sculpture) to the reinforced composite (FirbeKor) material were determined on 5 samples of each series after 24h and thermal cycling (TC: 6000 thermal cycles [5°C/55°C]) using different mechanical surface treatments (T1-T5). The system providing the most reliable bond strength values (CoJet, Espe) was used as a pre-treatment for the repair of 8 premolar FPDs. Fracture strengths (Zwick testing maschine; v=1mm/min) of the FPDs were determined after thermocycling and mechanical loading (TCML) (A), after first repair and TCML (B) and second repair and TCML (C). TCML was performed to simulate an intraoral wearing period of 5 years before and of 2 years after the repair. (6000 thermal cycles [5°C/55°C], 1.2x 106 mastication cycles [50N]= 5 years wearing period). Median and percentiles (25%/75%) were calculated. Statistical analysis was performed using Mann-Whitney-U- and Kruskal-Wallis-Test (p=0.05).
The repair of the glass-fiber-reinforced FPD with air abrading/silanisation pre-treatment and a light curing composite provides a confident fracture strength. If intraoral damage of FPD is caused only by splittering or fracture of the veneer without fibre injury, a replacement of the restoration can be avoided in some cases.