Naslov
Thickness of CAD-CAM composite resin overlays influences fatigue resistance of endodontically-treated premolars

Autori
Magne, Pascal ; Knežević, Alena

Izvornik
Dental materials (0109-5641) 25 (2009), 10; 1264-1268

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
composite resin overlays ; CAD/CAM ; fatigue

Sažetak
Evaluate the influence of composite resin CAD- CAM restoration thickness on the in-vitro fatigue resistance and failure mode of overlay- type restoration in endodontically treated premolars. Methods: Thirty extracted premolars received root canal treatment followed by a standardized tooth preparation (1.5, 2.5 or 3.5 mm cusp reduction, proximal gingival margins located 1.5 mm below the CEJ, glass-ionomer base and immediately sealed dentin with Optibond FL). Restorations were milled using Cerec3 and FiltekMZ100 composite resin blocks. The intaglio surfaces of the overlays were sandblasted and silanated. Tooth preparations were sandblasted and etched before insertion of the restoration. All restorations were luted with Optibond FL adhesive resin and preheated FiltekZ100. A closed-loop servo-hydraulic unit was used for simulating cyclic isometric chewing at 5 Hz, starting with a load of 200N (5, 000 cycles), followed by stages of 400, 600, 800, 1000, 1200 and 1, 400N at a maximum of 30, 000 cycles each. All samples were loaded until fracture or to a maximum of 185, 000 cycles. Groups were compared using the Kaplan- Meier survival curves. Results: None of the restored premolars with the 1.5mm cusp overlap restoration withstood all 185, 000 loading cycles (survival=0%). With 2.5mm and 3.5mm cusp overlap, the survival rate was 30% and 40%, respectively. The rate of fracture below the CEJ was 60%, 60% and 30% for 1.5, 2.5 and 3.5mm of cusp overlap, respectively. Survival of restored premolars with 2.5 and 3.5mm cusp coverage was not significantly different (p=.23). Conclusions: Thick FiltekMZ100 composite resin onlays (2.5 and 3.5mm cusp overlap) showed higher fatigue resistance than thin ones (1.5mm) and may be associated with fractures that are less subgingival. Clinical relevance: The results of this simulated fatigue study indicated the favorable behavior of thick CAD-CAM composite resin overlays on compromised endodontically-treated premolars, especially in high load situations. Immediate dentin sealing was an integral part of the bonding strategy. It cannot be concluded that thin CAD-CAM composite resin overlays are contra-indicated for endodontically-treated premolars because both thick and thin overlays withstood the normal range of bite forces simulated in the first part of the fatigue test.

Izvorni jezik
Engleski

Znanstvena područja
Dentalna medicina

POVEZANOST RADA