Influence of framework design on fracture strength of mandibular anterior all-ceramic resin-bonded fixed partial dentures.
OBJECTIVE
The purpose of this in vitro study was to evaluate the influence of the framework design on the fracture strength of all-ceramic resin-bonded fixed partial dentures (RBFPD) in the mandibular incisor region.


METHODS
Twenty-four aluminum oxide ceramic frameworks were copy milled with the Celay system, glass infiltrated, and veneered with feldspathic porcelain to replace a mandibular incisor. Forty-eight extracted human incisors were used as abutments by embedding them in a polyester resin. The master casts were fabricated according to a typical clinical case. The sandblasted restorations were bonded to the acid-etched abutment teeth with a composite resin. Twelve RBFPDs had a conventional two-retainer design, and 12 had a cantilevered single-retainer design. Subgroups of eight specimens were subjected to a quasistatic load in the direction of the long axis of the abutment teeth in a universal testing machine. Additional subgroups of four specimens were subjected under 0 degrees to dynamic loading of 25 N in a dual-axis chewing simulator.


RESULTS
The mean fracture strengths under quasistatic loading were 313 N (SD 42) for the two-retainer design and 291 N (SD 100) for the single-retainer design. The mean cycles sustained by specimens subjected to dynamic loading at 25 N were 50,081 (SD 42,705) for the two-retainer design and 297,099 (SD 508,439) for the single-retainer design. There was no statistically significant influence of the framework design on the fracture strength of the restorations under quasistatic or dynamic loading.


CONCLUSIONS
The clinical application of cantilevered all-ceramic RBFPDs in the mandible may be an alternative to all-ceramic RBFPDs with two retainers.
Koutayas
Spiridon Oumvertos
SO
Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University, Kiel, Germany.
Kern
Matthias
M
Ferraresso
Franco
F
Strub
Jörg Rudolf
JR
D000134:Acid Etching, Dental; D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000704:Analysis of Variance; D001732:Bite Force; D002516:Ceramics / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry; D017076:Computer-Aided Design; D000044:Dental Abutments; D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003801:Dental Veneers; D003779:Denture Design; D016379:Denture, Partial, Fixed, Resin-Bonded; D005898:Glass / Q000737:chemistry; D006801:Humans; D007180:Incisor; D008334:Mandible; D008409:Mastication / Q000502:physiology; D008422:Materials Testing; D017680:Potassium Compounds / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
D000538:Aluminum Silicates; D003188:Composite Resins; D017680:Potassium Compounds; D003776:Dental Porcelain; C016447:feldspar; D000537:Aluminum Oxide