ABSTRACT
AIM: To evaluate microspace and microleakage between implant and abutments subjected to pre- and post-calibrated cyclic stress. MATERIALS AND METHODS: Twelve screw-retained implant prostheses with BioHPP polyetheretherketone (PEEK) abutment (Noris Dental Implant System Ltd., Nesher, Israel) (Group I) and 12 screw-retained implant prostheses with computer-assisted design/computer-assisted manufacturing (CAD/CAM) milled zirconia abutment (DentGallop, Houston, TX, USA) (Group II) were connected to their respective implant, and the prosthetic screw was torqued to 30N/cm (Noris). The microspace was evaluated using scanning electron microscopy (SEM; TeScan, Brno, Czech Republic). Twenty-four samples were then induced to cyclic stress (Lokesh Industries, Pune, India) simulating 180 days duration of oral stress. The microspaces (Group IA and Group IIB) were measured post-cyclic stress. Group I and II were again renamed into Group Ia and Group IIb for microbial study. Both implant assemblies were immersed in fresh soybean casein digest broth (SCDB) (Himedia, Mumbai, India) and subsequently inoculated with 1.0µL E. coli suspension (Himedia) at the open end and incubated at 37ºC for seven days. After the incubation period, cellular activity was determined by the spread plate method, and total colony-forming units (CFU) were calculated. The results were evaluated using independent T and Mann-Whitney tests. RESULT: Average and microspace at the implant-abutment junction of Group I samples in the front right was 12.98µm, center 13.76µm, front left 13.22µm, and in Group II samples, the front right was 18.52µm, center 17.84µm, front left 18.58µm.After being subjected to cyclic loading, the mean levels of the vertical microgap for Group IA samples were: in the front right region 10.37µm, in the center 9.34µm, in the front left 10.51µm and in Group IIB samples front right was 14.59µm, center 13.39µm, front left 13.8µm. Independent t-tests showed insignificant differences between the two groups. The median value of microbial leakage of Group Ia samples after cyclic loading was 30 x 103 CFU/ml, and Group IIb samples were 42 x 103 CFU/ml and were significant. CONCLUSION: There was minimal variation in the mean microspace between the BioHPP PEEK abutment and CAD/CAM milled zirconia abutment, and it was insignificant before and after cyclic stress. BioHPP PEEK abutment-titanium implant interfaces showed significantly decreased microbial leakage than CAD/CAM milled zirconia abutment-titanium implant interfaces after cyclic stress.
ABSTRACT
PURPOSE: To comparatively evaluate the wear resistance of two different implant abutment materials with titanium implants after cyclic loading. METHODOLOGY: Two groups utilizing 20 titanium implants secured in resin blocks, in which 10 titanium implants are connected with titanium abutments (Group I, n = 10) and the other 10 titanium implants are connected with Polyether ether Ketone (PEEK) abutments (Group II, n = 10). Abutments are cyclically loaded for 550,000 cycles. Surface profilometry, scanning electron microscopy (SEM), and energy-dispersive X-ray spectrometry (EDS) are carried out for all the abutment in both Group I and Group II before and after cyclic loading. The abutment surface at the implant-abutment interface is analyzed for wear. RESULTS: On comparison using independent "t"-test, it was found that the mean difference values of pre- and post-cyclic loading surface roughness (Ra value) of Group I (premachined titanium straight abutments) (-0.073 µm) was lower than the Group II test samples (premachined PEEK straight abutments) (-0.0004 µm), and this was found to be statistically insignificant (P = 0.272). SEM micrographs and EDS results also corroborate with the results of surface profilometry. CONCLUSION: The new concept in this study is Group II (PEEK abutments) are connected with titanium implants, to prove its compatibility and aesthetics. Within the limitations of the study, the surface roughness values before and after cyclic loading of two different abutment materials revealed that the wear resistance of titanium abutments is more than PEEK abutments, but the difference was found to be statistically insignificant.
