Aim: The objective of this investigation was to assess and compare the retention
of two implants that maintained complete mandibular overdentures with telescopic
attachments made entirely of zirconia (ZrO2), entirely of polyether-ether-ketone
(PEEK), and ZrO2-PEEK ,Subjects and methods: Three acrylic edentulous mandibular
overdenture models were separated into three main groups based on their telescoping
attachment systems: group ZZ was made up entirely of ZrO2; PP group was made
entirely of PEEK; and ZP group was made up entirely of ZrO2 (primary crown)-PEEK
(secondary crown). The acrylic models were scanned with a laboratory scanner to gain
a three‐dimensional (3D) virtual image and the primary crowns were CAD designed
to ensure a similar insertion route and then milled from ZrO2 and PEEK blanks. Each
primary crown was then scanned separately and the secondary crown was created with
mechanical projections and then milled. After that, mandibular acrylic overdenture with
a metal framework and the metallic lingual bar were fabricated. For measuring the
retention forces of each telescopic crown type, a universal testing machine (UTM) was
utilized to employ 400, 600, 1200, 1500, and 1800 cycles of removal and insertion to
the metal bar during the retention test. Results: The outcomes revealed that the ZZ
group possessed significantly greater mean retentive forces followed by PP and then
the ZP group. However, the retentive forces decreased respectively with an increase
in the number of cycles. Conclusion: Despite the loss of retention over time, PEEK
remains suitable for use as a secondary telescopic crown in substitution of zirconia or
PEEK main crowns