Dynamic and static strength of an implant-supported overdenture model reinforced with metal and nonmetal strengtheners.
BACKGROUND
Fractures of overdentures occur in the denture base through the abutments.


OBJECTIVE
The purpose of this study was to evaluate the effect of reinforcements and the space available for their placement on the dynamic and static loading capacity of a simulated implant-supported overdenture model.


METHODS
Rhomboidal (6 × 6 × 25 mm) test specimens (n=8), made with an acrylic resin and containing 2 metal O-ring capsules, were reinforced with braided stainless steel bar (BS), stainless steel mesh (SM), unidirectional E-glass fiber (GF), E-glass mesh (GM), woven polyethylene braids (PE), or polyaramid fibers (PA). Two distinct spaces for reinforcement placement were investigated: a 2.5 mm and a 1 mm space. Control groups consisted of nonreinforced specimens. Specimens were thermocycled (5°C and 55°C, 5,000 cycles) and then subjected to a 100,000 cyclic load regime. Unbroken specimens were then loaded until failure. The number of failures under fatigue (f) and static load (s) were compared with the Chi-Square test, while static load means were compared with the Kruskal-Wallis test (α=.05).


RESULTS
The number of failures (f:s) of GF (0:16), PE (0:16), and PA (0:16) differed significantly from the control group (8:8) and SM (4:12) (P=.037 and P=.025, respectively). For the 2.5 mm space group, these same reinforcements also exhibited higher static load means than the control (P=.016, P=.003, and P=.003, respectively); under static load, no significant differences were detected between the reinforced groups and the control for the 1.0 mm space group (P=1.0).


CONCLUSIONS
E-glass fibers, woven polyethylene braids, and polyaramid fibers withstood the fatigue regime and increased the flexural strength of the implant-supported overdenture model. The spaces available for reinforcement did not affect the dynamic strength or the static loading capacity of the implant-supported overdenture model.
Pontifical Catholic University of Parana, Curitiba, Parana, Brazil. r.rached@pucpr.br
Rodrigo Nunes
RN
Rached
Evelise Machado
EM
de Souza
Scott R
SR
Dyer
Jack Liborio
JL
Ferracane
D000180:Acrylic Resins / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003722:Dental Alloys / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D003779:Denture Design; D003828:Denture, Overlay; D055119:Elastic Modulus; D005898:Glass / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D009757:Nylons / Q000737:chemistry; D018583:Pliability; D020959:Polyethylene / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors; D014867:Water
D000180:Acrylic Resins; D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; D009757:Nylons; D011108:Polymers; C485628:Stick resin; C009753:fiberglass; C111780:polyaramide; D014867:Water; C078906:Herculite Condensable; D013193:Stainless Steel; C058852:Kevlar 49; C040291:Lucitone; D020959:Polyethylene; D019904:Polymethyl Methacrylate