The mode of failure analyzed by scanning electron microscope was found to be adhesive failure between the adhesive and adherent. G-CEM LinkAce showed highest shear bond strength even before and after thermal cycling. Reduction in shear bond strength is more in RelyX Unicem (52.2%) than G-CEM LinKace (20.9%). Shear bond strengths was obtained by dividing the failure load with the bonding area in conformity with the study done by S.T. The maximum load at failure was recorded by the system's software. Load was applied parallel to the long axis of the specimen through a wedge at the PEEK resin cement interface. Specimens were held in a metal holder in a UTM. ISO TR 11405 (1994) – Number of cycles: 500 cycles Temperature: 5–55° Dwell time ≥20 s. Each half from group (A&B) was subjected to thermocycling for 20 s at 5☌ and 55☌ with a 5-s interval between each cycle. (2015), is adopted in our study to ensure a precise fit of the resin cements to PEEK sample. The technique, as described by Darius Raudy et al. Cylindrical putty mold index of 5 mm in diameter and 4 mm in height was used to guide the application of resin cements in accordance with Jung lee et al. Samples were divided into two groups with Group I cemented with RelyX Unicem (20 samples were divided into each half control and test groups) and Group II cemented with G-CEM LinkAce (20 samples were divided into each half control and test groups). RelyX Unicem and GC G-CEM LinkAce used in this study are dual-cure self-adhesive universal resin cements. To enhance the mechanical bond strength, sandblasting is an effective method to change surface morphology of materials. In this study, CAD CAM technique was used for the fabrication of PEEK samples, in which a steel die of dimensions 1 cm × 3 mm was sprayed with titanium dioxide and scanned, which is in conformity with the study done by Merk et al. (2013) reported the advantages of CAD-CAM technique such as decreased number of appointments, decreased duration of prosthesis manipulation, easy manufacturing of trial dentures using stored digital data, and highly precise, shape, or quality. (2005) stated that the tensile strength of PEEK is equivalent to bone, enamel, and dentin, which makes it more acceptable.ĬAD CAM milling is used for fabrication of PEEK prosthesis, injection molding, or pressing. Thermal cycling is an in-vitro method to increase the aging of restorative materials Amaral et al. Shear bond strength test is a evaluation procedure which is used to test the adhesion of the dental cement. SEM images of RelyXUnicem and G-CEM LinkAce specimens showed adhesive type of failure. Graphical bar representation depicts that RelyX test showed a maximum loss of SBS and G-CEM test group showing minimum loss of SBS. G-CEM linkage showed maximum SBS after thermocycling and RelyX unicem showed minimum. Comparison of shear bond strength between RelyX and G-CEM after thermocycling represent a significant difference in shear bond strength ( P < 0.005). Comparison of shear bond strength between G-CEM control and G-CEM test was done using paired t test in which the mean bond strength and standard deviation of G-CEM control and G-CEM test was found to be 5.07, 0.95 and 4.01, 0.68, respectively. There was significant difference in mean shear bond strength of RelyX group ( P < 0.0001). The mean of the test group was 1.87 and standard deviation was 0.43. Comparison of shear bond strength between RelyX control and RelyX test was done using paired t test in which the mean of the control group was 3.91 and standard deviation was 0.38. All P values ( P < 0.05) were considered as statistically significant. The paired t-test was used for comparison between two groups.
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