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. 2022 Feb 20;15(4):1582.
doi: 10.3390/ma15041582.

Assessment of Preload Loss after Cyclic Loading in the OT Bridge System in an "All-on-Four" Rehabilitation Model in the Absence of One and Two Prosthesis Screws

Mario Cesare Pozzan  1 , Francesco Grande  1   2 , Edoardo Mochi Zamperoli  1 , Fabio Tesini  1 , Massimo Carossa  2 , Santo Catapano  1
Affiliations

Assessment of Preload Loss after Cyclic Loading in the OT Bridge System in an "All-on-Four" Rehabilitation Model in the Absence of One and Two Prosthesis Screws

Mario Cesare Pozzan et al. Materials (Basel). .

Abstract

The aim of this study was to evaluate the stability of prosthetic screws after applying cyclic loadings in an "all-on-four" rehabilitation model with the OT Bridge system. The model was tested both with and without anterior screws. Four implant analogues following the "all-on-four" concept were inserted in an edentulous mandibular resin model. An OT Bridge system with a Cr-Co prosthetic framework was fabricated. Depending on the presence or absence of one or two anterior screws on the implant analogues, three groups were created, i.e., Gr.1: three tightening screws, Gr.2: two tightening screws, Control Group: four tightening screws. Each single group underwent subsequent 400,000 cyclic loads, simulating approximately a year of chewing by using a dynamometer machine. This cycle was repeated five times for each group, and preload loss values were evaluated on each prosthetic screw after each cycle. All the data obtained were analyzed by one-way ANOVA and Student's t-test. No statistically significant differences after intragroup analysis were found. A statistically significant difference within the Gr.1 between the screws in positions 33 and 36, equal to 15.2% (p-value = 0.0176), was found. The OT Bridge seems a useful system to maintain the retention of a prosthesis during mechanical stress conditions even in the absence of one screw in an "all-on-four" rehabilitation. This could represent a good solution to solve the esthetic problem of the screw buccal access hole for fixed solutions.

Keywords: OT bridge; all-on-four; implant-supported prosthesis; loosening torque; preload loss; prosthetic connection.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Lateral (a) and frontal views (b) of the model used.
Figure 2
Figure 2
Representative images of the screws’ placement in the three different groups. From the left to the right: Gr.1 (a), Gr.2 (b), and Gr.CTR (c).
Figure 3
Figure 3
Representative image of the model placement under the MTS Acumen.
Figure 4
Figure 4
Image of the model during a cyclic load in the water bath.
See this image and copyright information in PMC

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