Abstract
Statement of problem
The loss in the retentive capability of implant-supported overdenture attachments
has been related to the wear of the retentive inserts. Wear of the abutment coating
material when following the replacement period for the retentive inserts requires
investigation.
Purpose
The purpose of this in vitro study was to compare the changes in retentive force of
3 polyamide and a polyetheretherketone denture attachments under repeated insertion
and removal cycles in wet conditions while following their manufacturers’ replacement
time recommendations.
Material and methods
Four different denture attachments (LOCKiT, OT-Equator, Ball attachment, and Novaloc)
with their retentive inserts were tested. Four implants were embedded into individual
acrylic resin blocks, and 10 abutments for each attachment were used. Forty metal
housings with their retentive inserts were attached to polyamide screws with autopolymerizing
acrylic resin. A customized universal testing machine was used to simulate insertion
and removal cycles. The specimens were mounted on a second universal testing machine
at 0, 540, 2700, and 5400 cycles, and the maximum retentive force was recorded. The
retentive inserts for LOCKiT (light retention), OT-Equator (soft retention), and Ball
attachment (soft retention) were replaced every 540 cycles, while the Novaloc (medium
retention) attachments were never replaced. All the abutments were weighed with a
precision scale at 0, 2700, and 5400 cycles. The surface of every abutment was examined
under a stereomicroscope at ×10 magnification. Data were analyzed with descriptive
statistics. Two-way repeated measures ANOVA was used to compare the mean retentive
force and mean abutment mass of all groups and time evaluation points. Bonferroni
corrections were made to adjust for multiple tests (α=.05).
Results
The mean retention loss for LOCKiT was 12.6% after 6 months and 45.0% after 5 years
of simulated use. The mean retention loss for OT-Equator was 16.0% after 6 months
and 50.1% after 5 years of simulated use. The mean retention loss for Ball attachment
was 15.3% after 6 months and 39.1% after 5 years of simulated use. The mean retention
loss for Novaloc was 31.0% after 6 months and 59.1% after 5 years of simulated use.
The mean abutment mass difference was statistically significant (P<.05) for LOCKiT and Ball attachment but not statistically significant (P>.05) for OT-Equator and Novaloc at baseline, 2.5 years, and 5 years.
Conclusions
All tested attachments recorded retention loss under the experimental conditions,
even when their manufacturers’ recommendations for replacement time for the retentive
inserts were followed. Patients should be aware that implant abutments should be replaced
after a recommended period since their surfaces also change over time.
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Article info
Publication history
Published online: May 25, 2023
Publication stage
In Press Corrected ProofFootnotes
Funding: Supported by MIS Implants Technologies Ltd and Denco Dental.
Conflicts of Interest: Prof Argirios Pissiotis reports that equipment, drugs, or supplies was provided by MIS Implants Technologies Ltd and Denco Dental.
Identification
Copyright
© 2023 by the Editorial Council for The Journal of Prosthetic Dentistry.
