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      Effect of different angulations and collar lengths of conical hybrid implant abutment on screw loosening after dynamic cyclic loading


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          The purpose of this in vitro study was to evaluate the effect of different angulations and collar lengths of the implant abutment on screw loosening by measuring removal torque value (RTV) before and after dynamic cyclic loading using digital torque gauge.


          A total 90 sets of 4.5 mm diameter × 10 mm length bone level implants with conical hybrid connection were used. They were divided equally according to abutment angulation, into three groups: GI 0° abutment, GII 15° abutment, and GIII 25°. Each group was divided into two subgroups, 15 each, according to collar height: subgroup A (2 mm) and subgroup B (4 mm). Each implant and abutment assembly was positioned vertically in the center of the acrylic resin block using stainless steel cylindrical split mold. Initial analysis was made by abutment screw tightened with 30 Ncm torque twice with 10-min intervals using a digital torque gauge. RTV before and after cyclic loading of the abutment screws were measured in newton centimeter using digital torque gauge. One hundred thousand cycles of eccentric dynamic cyclic loading, at 130 N at a rate of 1 Hz, were applied 5 mm away from the central axis of the implant fixture. Percentage of removal torque loss (%RTL) before and after dynamic cyclic loading were calculated and statistically analyzed using the SPSS version 20.


          For GI, %initial RTL was 25.0 ± 1.5% and decreased significantly after loading (23.5 ± 2.3%). For GII, %initial RTL was 25.5 ± 1.4% and increased significantly after loading (33.4 ± 3.7%). For GIII, %initial RTL was 25.944 ± 1.2% and increased significantly after loading (40.1 ± 5.1%). There was significant effect on screw loosening for abutment angulations and collar lengths.


          Within the limitations of this study, results suggested that screw loosening increases with increasing abutment angulations and collar lengths after dynamic cyclic loading.

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          Most cited references34

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          Performance of conical abutment (Morse Taper) connection implants: a systematic review.

          In this systematic review, we aimed to compare conical versus nonconical implant-abutment connection systems in terms of their in vitro and in vivo performances. An electronic search was performed using PubMed, Embase, and Medline databases with the logical operators: "dental implant" AND "dental abutment" AND ("conical" OR "taper" OR "cone"). Names of the most common conical implant-abutment connection systems were used as additional key words to detect further data. The search was limited to articles published up to November 2012. Recent publications were also searched manually in order to find any relevant studies that might have been missed using the search criteria noted above. Fifty-two studies met the inclusion criteria and were included in this systematic review. As the data and methods, as well as types of implants used was so heterogeneous, this mitigated against the performance of meta-analysis. In vitro studies indicated that conical and nonconical abutments showed sufficient resistance to maximal bending forces and fatigue loading. However, conical abutments showed superiority in terms of seal performance, microgap formation, torque maintenance, and abutment stability. In vivo studies (human and animal) indicated that conical and nonconical systems are comparable in terms of implant success and survival rates with less marginal bone loss around conical connection implants in most cases. This review indicates that implant systems using a conical implant-abutment connection, provides better results in terms of abutment fit, stability, and seal performance. These design features could lead to improvements over time versus nonconical connection systems.
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            Timing of loading and effect of micromotion on bone-dental implant interface: Review of experimental literature

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              Mechanical complications of dental implants


                Author and article information

                Int J Implant Dent
                Int J Implant Dent
                International Journal of Implant Dentistry
                Springer Berlin Heidelberg (Berlin/Heidelberg )
                3 December 2018
                3 December 2018
                December 2018
                : 4
                : 39
                ISNI 0000 0000 9477 7793, GRID grid.412258.8, Prosthodontic Department, Faculty of Dentistry, , Tanta University, ; Elgeish St., Tanta, Egypt
                © The Author(s). 2018

                Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

                : 7 May 2018
                : 11 October 2018
                Custom metadata
                © The Author(s) 2018

                removal torque loss,abutment angulation,abutment collar height,dynamic cyclic loading,digital torque gauge,screw loosening


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