Retention and wear assessment of novel PolyEtherKetoneKetone versus traditional cobalt chromium material used in digital double crown retained removable partial dentures

Abstract

BACKGROUND: Conventional removable partial dentures (RPDs) involve a process that is often susceptible to errors and demands a significant investment of time. The introduction of computer-aided design and computer-aided manufacturing (CAD/CAM) technology and materials witnessed significant advancements in recent years to produce accurate removable partial dentures. This study evaluated the retention and wear of PolyEtherKetoneKetone (PEKK) compared to Cobalt-Chromium (CoCr) in digitally fabricated double crown removable partial dentures for lower Kennedy Class I cases. METHODS: The study was performed on 3D digital models of mandibular Kennedy Class I with prepared premolars bilaterally. The double crown RPDs were designed and fabricated digitally to get 14 copies of RPDs. Two groups were defined (n = 7); the first group were milled from Co-Cr discs, and the other's from PEKK blanks. Initial retention was measured using a universal testing machine. RPDs were then subjected to dynamic loading in a chewing simulator over 100,000 cycles followed by 540 manual insertion and removal cycles and were remounted on the testing machine to measure final retention simulating six months. Wear was assessed using Geomagic Control X software, where negative deviations highlighted areas of degradation. Data was collected and analyzed for statistical analysis. Two Sample t-test was used to compare between the two groups and Paired t test to study the changes within each group. The significance level was set at P ≤ 0.05. RESULTS: PEKK group showed a statistically significantly higher final retentive values after 6 months (11.6 N) than Co-Cr (2 N). Moreover, results showed higher retention loss in Co-Cr group (16.9 N) compared to PEKK (3.7 N). Additionally, wear assessment of primary copings indicated a higher deviation in the Co-Cr group (-0.25 mm) compared to PEKK (-0.096 mm), with a notable correlation (0.651, P-value = 0.011) between retention loss and wear. CONCLUSIONS: Within the limitation of this study, it could be concluded that PEKK provided digitally fabricated double crown RPDs with higher retention values and less wear than Co-Cr after simulation of 6 months of RPD use.