Effect of water storage on the shear strength and fatigue limit of the reline resin bond to denture base resins.
OBJECTIVE
This study evaluated the effect of water storage (WS) on the shear bond strength (SBS) and shear bond fatigue limit (SBFL) between denture base and reline resins. In addition, a possible correlation between SBS and SBFL was evaluated.


METHODS
Two denture base (Lucitone 550-L and Acron MC-AC) and two reline resins (Ufi Gel Hard- UGH and Tokuso Rebase Fast-TR) were selected. Cylinders (20 x 20 mm) of each denture base resin were processed, and the reline resins were packed on the bonding surfaces using a split mold (3.5 x 5.0 mm). Specimens of each denture base-reline resin combination were subjected to shear forces (0.5 mm/min) until fracture. A staircase approach was used to determine the SBFL. Specimens were submitted to either 10,000 cycles (5.0 Hz) or until fracture. For both SBS and SBFL, specimens were tested after relining (control) and after 30 days of WS. Data (MPa) were analyzed with 2-way ANOVA and Tukey's tests (α = 0.05). To test for a possible correlation between the SBS and SBFL, a linear regression analysis was performed.


RESULTS
WS significantly increased (p < 0.05) the SBS of AC-TR and AC-UGH and the SBFL of AC-TR, AC-UGH and LUGH. After WS, UGH produced higher (p < 0.05) SBS than TR, regardless of the denture base resin used. Regardless of the experimental groups and the denture base resins used, UGH produced higher (p < 0.05) SBFL than TR specimens. A strong positive linear correlation (r(2) = 0.949) was observed between the SBS and SBFL.


CONCLUSIONS
Overall, UGH promoted the highest SBS and SBFL. WS increased the SBS and SBFL of the AC relined specimens. A positive correlation was observed between the two variables.
Vergani
Carlos Eduardo
CE
Department of Dental Materials and Prosthodontics, São Paulo State University-UNESP, Araraquara Dental School, SP, Brazil. vergani@foar.unesp.br
Seó
Rosangela Seiko
RS
Reis
José Maurício
JM
Giampaolo
Eunice Teresinha
ET
Pavarina
Ana Cláudia
AC
Machado
Ana Lucia
AL
D000180:Acrylic Resins; D000704:Analysis of Variance; D001840:Dental Bonding; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D003819:Denture Bases; D003822:Denture Liners; D003823:Denture Rebasing; D016014:Linear Models; D008422:Materials Testing; D008689:Methacrylates; D033081:Shear Strength; D012826:Silicone Elastomers; D018709:Statistics, Nonparametric; D014867:Water
D000180:Acrylic Resins; D008689:Methacrylates; D012826:Silicone Elastomers; C503430:Tokuso Rebase Fast; C483158:Ufi gel; D014867:Water; C075051:Acron MC; C040291:Lucitone