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Fracture resistance of metal-free composite crowns-effects of fiber reinforcement, thermal cycling, and cementation technique.
J Prosthet Dent. 2004 Sep; 92(3):258-64.JP

Abstract

STATEMENT OF PROBLEM

The improved mechanical properties of contemporary composites have resulted in their extensive use for the restoration of posterior teeth. However, the influence of fiber reinforcement, cementation technique, and physical stress on the fracture resistance of metal-free crowns is unknown.

PURPOSE

This in vitro study evaluated the effect of fiber reinforcement, physical stress, and cementation methods on the fracture resistance of posterior metal-free Sinfony crowns.

MATERIAL AND METHODS

Ninety-six extracted human third molars received a standardized tooth preparation: 0.5-mm chamfer preparation and occlusal reduction of 1.3 to 1.5 mm. Sinfony (nonreinforced crowns, n=48) and Sinfony-Vectris (reinforced crowns, n=48) crowns restoring original tooth contour were prepared. Twenty-four specimens of each crown type were cemented, using either glass ionomer cement (GIC) or resin cement. Thirty-two crowns (one third) were stored in humidity for 48 hours. Another third was exposed to 10,000 thermal cycles (TC) between 5 degrees C and 55 degrees C. The remaining third was treated with thermal cycling and mechanical loading (TCML), consisting of 1.2 million axial loads of 50 N. The artificial crowns were then vertically loaded with a steel sphere until failure occurred. Significant differences in fracture resistance (N) between experimental groups were assessed by nonparametric Mann-Whitney U-test (alpha=.05).

RESULTS

Fifty percent of the Sinfony and Sinfony-Vectris crowns cemented with glass ionomer cement loosened after thermal cycling. Thermal cycling resulted in a significant reduction in the mean fracture resistance for Sinfony crowns cemented with GIC, from 2037 N to 1282 N (P=.004). Additional fatigue produced no further effects. Fiber reinforcement significantly increased fracture resistance, from 1555 N to 2326 N (P=.001). The minimal fracture resistance was above 600 N for all combinations of material, cement and loading.

CONCLUSION

Fracture resistance of metal-free Sinfony crowns was significantly increased by fiber reinforcement. Adhesive cementation may be recommended to avoid cementation failure.

Authors+Show Affiliations

Rupprecht-Karls University, Heidelberg, Germany. Franziska_Lehmann@med.uni-heidelberg.deNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

15343161

Citation

Lehmann, Franziska, et al. "Fracture Resistance of Metal-free Composite Crowns-effects of Fiber Reinforcement, Thermal Cycling, and Cementation Technique." The Journal of Prosthetic Dentistry, vol. 92, no. 3, 2004, pp. 258-64.
Lehmann F, Eickemeyer G, Rammelsberg P. Fracture resistance of metal-free composite crowns-effects of fiber reinforcement, thermal cycling, and cementation technique. J Prosthet Dent. 2004;92(3):258-64.
Lehmann, F., Eickemeyer, G., & Rammelsberg, P. (2004). Fracture resistance of metal-free composite crowns-effects of fiber reinforcement, thermal cycling, and cementation technique. The Journal of Prosthetic Dentistry, 92(3), 258-64.
Lehmann F, Eickemeyer G, Rammelsberg P. Fracture Resistance of Metal-free Composite Crowns-effects of Fiber Reinforcement, Thermal Cycling, and Cementation Technique. J Prosthet Dent. 2004;92(3):258-64. PubMed PMID: 15343161.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Fracture resistance of metal-free composite crowns-effects of fiber reinforcement, thermal cycling, and cementation technique. AU - Lehmann,Franziska, AU - Eickemeyer,Grit, AU - Rammelsberg,Peter, PY - 2004/9/3/pubmed PY - 2004/11/5/medline PY - 2004/9/3/entrez SP - 258 EP - 64 JF - The Journal of prosthetic dentistry JO - J Prosthet Dent VL - 92 IS - 3 N2 - STATEMENT OF PROBLEM: The improved mechanical properties of contemporary composites have resulted in their extensive use for the restoration of posterior teeth. However, the influence of fiber reinforcement, cementation technique, and physical stress on the fracture resistance of metal-free crowns is unknown. PURPOSE: This in vitro study evaluated the effect of fiber reinforcement, physical stress, and cementation methods on the fracture resistance of posterior metal-free Sinfony crowns. MATERIAL AND METHODS: Ninety-six extracted human third molars received a standardized tooth preparation: 0.5-mm chamfer preparation and occlusal reduction of 1.3 to 1.5 mm. Sinfony (nonreinforced crowns, n=48) and Sinfony-Vectris (reinforced crowns, n=48) crowns restoring original tooth contour were prepared. Twenty-four specimens of each crown type were cemented, using either glass ionomer cement (GIC) or resin cement. Thirty-two crowns (one third) were stored in humidity for 48 hours. Another third was exposed to 10,000 thermal cycles (TC) between 5 degrees C and 55 degrees C. The remaining third was treated with thermal cycling and mechanical loading (TCML), consisting of 1.2 million axial loads of 50 N. The artificial crowns were then vertically loaded with a steel sphere until failure occurred. Significant differences in fracture resistance (N) between experimental groups were assessed by nonparametric Mann-Whitney U-test (alpha=.05). RESULTS: Fifty percent of the Sinfony and Sinfony-Vectris crowns cemented with glass ionomer cement loosened after thermal cycling. Thermal cycling resulted in a significant reduction in the mean fracture resistance for Sinfony crowns cemented with GIC, from 2037 N to 1282 N (P=.004). Additional fatigue produced no further effects. Fiber reinforcement significantly increased fracture resistance, from 1555 N to 2326 N (P=.001). The minimal fracture resistance was above 600 N for all combinations of material, cement and loading. CONCLUSION: Fracture resistance of metal-free Sinfony crowns was significantly increased by fiber reinforcement. Adhesive cementation may be recommended to avoid cementation failure. SN - 0022-3913 UR - https://www.unboundmedicine.com/medline/citation/15343161/Fracture_resistance_of_metal_free_composite_crowns_effects_of_fiber_reinforcement_thermal_cycling_and_cementation_technique_ DB - PRIME DP - Unbound Medicine ER -