Effect of implant connection and restoration design (screwed vs. cemented) in reliability and failure modes of anterior crowns

Abstract

The mechanical performance of cemented or screw-retained implant-supported crowns with an internal or external configuration is yet to be understood. This in vitro study evaluated the effect of screw-retained and cement-retained prostheses on internal and external implant-abutment connections. Thereby, the reliability and failure modes of crowns were investigated. Eighty-four implants (Emfils; Colosso Evolution system) were divided into four groups (n=21 each): screw-retained and internal connection (Si), screw-retained and external connection (Se), cement-retained and internal connection (Ci), and cement-retained and external connection (Ce). Ti-6Al-4V abutments were torqued (30 Ncm) to the implants, and maxillary central incisor metal crowns were torqued (30 Ncm) or cemented (Rely X Unicem; 3M-ESPE) and subjected to accelerated life-testing in water. Use-level probability Weibull curves and reliability for 50,000 cycles at 150 N were calculated. The β values for Si (1.72), Se (1.50), Ci (1.34), and Ce (1.77) groups indicated that fatigue/damage accumulation accelerated their failure. The Ci group presented the highest reliability, the Se group presented the lowest reliability, and Si and Ce groups presented intermediate reliability. Screw-retained restorations presented mainly abutment fracture. Cement-retained restorations resulted in failures of the screw in the Ce group, but implant/screw fracture in the Ci group.

Reliability evaluation of alumina-blasted/acid-etched versus laser-sintered dental implants

“…Similar findings were reported when accelerated life tests were used in implant-borne reconstructions [19]. Considering the unknown mechanical performance of direct laser metal sintering as a process for implant fabrication, the aim of this study was to evaluate the reliability and failure modes of anatomically correct maxillary central incisor crowns as a function of supporting titanium implant structure (laser sintered vs alumina blasted/acid etched).…”

“…The prescribed fatigue method was step-stress accelerated life-testing under water at 9 Hz with a servo-all-electric system (TestResources 800L, Shakopee, MN, USA) where the indenter contacted the incisal edge, applied the prescribed load within the step profile and lifted off the incisal edge. Fatigue testing was performed until failure (bending or fracture of the fixation screw, and/or bending, partial fracture, or total fracture of the abutment) or survival (no failure occurred at the end of step-stress profiles, where maximum loads were up to 600 N) [19].…”

“…Several testing methods have been described for the mechanical evaluation of implant systems, such as single load to fracture [15], the use fatigue followed by the application of a static load until fracture [16,17], the staircase method [18], fatigue limit (ISO 14801:2007), step-stress accelerated life testing [19], and others. While the ISO 14801:2007 was created with the aim to standardize the testing procedures and data presentation in fatigue of dental implants, it has been shown that results produced by such method should be interpreted with caution.…”

Is the internal connection more efficient than external connection in mechanical, biological, and esthetical point of views? A systematic review

“…Weng et al [43]; Weng et al [44] Evaluation of different surgical approaches (submerged and/or nonsubmerged implants) Steinebrunner et al [45] Evaluation of fatigue and fracture strength of different implant-abutment connections Bernardes et al [46] Comparison of two types of vertical compressive load from different implant-abutment interfaces Novaes Jr et al [47]; Barros et al [48] Evaluation of different interimplant distances and placement depth of implants restored with platform switch Rodríguez-Ciurana et al [49] Evaluation of biologic width of abutments with different diameters Nishioka et al [50] Comparison between machined and plastic copings Jesus Tavarez et al [51] Evaluation of vertical misfit alterations of the implant/abutment interface when subjected to cyclic loading Nishioka et al [52] Evaluation of different abutment designs and fixture alignments Pieri et al [53] Comparison between implants restored with platform switch or conventional abutments Freitas Jr et al [54] Evaluation of screw-retained and cement-retained prostheses Pessoa et al [55] Comparison between different commercially available designs of one connection type of immediately placed implants Oliva et al [56] Evaluation of full-arch rehabilitation with three implants (all on three) Diez et al [57] Evaluation of the implant-abutment interface with diamond-like carbon-coated screws Arnhart et al [58] Evaluation of a variable thread dental implant design Freitas Jr et al [59] Evaluation of reliability and failure modes of different abutments used for anterior restorations Tang et al [60] Investigation of mechanical characteristics of different implant-abutment interface designs Rack et al [61] Evaluation of the effect of cyclic loading at implants and abutment deformation Kopp et al [62] Did not report the type of connection used Gehrke [63] Evaluation of the resistance to static fatigue implants with various connections at different crown heights Teixeira et al [64] Evaluation of different profiles of implants submitted to torsion test…”

Avaliação da capacidade de selamento de intermediários UCLA em um sistema de implante de hexágono externo

“…Portanto, parece ocorrer menos micromovimentos nos implantes com conexões internas e, consequentemente, com maior probabilidade de longevidade quando submetidos à cargas do tipo fadiga oclusal (FREITAS et al, 2011).…”