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Influence of abutment fabrication method and fixation mode on the three-dimensional fit and reliability of implant-supported prostheses

Ramalho, Ilana Santos

Biblioteca Digital de Teses e Dissertações da USP; Universidade de São Paulo; Faculdade de Odontologia de Bauru 2019-08-20

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  • Título:
    Influence of abutment fabrication method and fixation mode on the three-dimensional fit and reliability of implant-supported prostheses
  • Autor: Ramalho, Ilana Santos
  • Orientador: Bonfante, Estevam Augusto; Magalhães, Ana Carolina
  • Assuntos: Implantes Dentários; Confiabilidade; Projeto Auxiliado Por Computador; Microct; Computer-Aided Design; Dental Implants; Dental Implant-Abutment Interface; Dental Implant-Abutment Designs; Reliability
  • Notas: Tese (Doutorado)
  • Descrição: Objectives. To evaluate the effect of abutment fabrication method on the threedimensional fit at the implant-abutment interface and its correlation with stress at fatigue failure of prostheses. Probability of survival (reliability) and fractography to characterize failure modes were also performed for cemented and screw-retained prostheses. Methods. Central incisor crowns were milled to restore implants and divided in 3 cemented and 3 screwed-retained groups, as follows (n=21/group): [Digital-Sc]: milled one-piece monolithic abutment/crown; [TiB-Sc]: milled crowns cemented onto Ti-base abutments; [UCLA]: screw-retained crown using UCLA abutments; [Digital- Ce]: milled two-piece assembly comprised by screwed monolithic abutment and a cemented crown; [TiB-Ce]: milled coping cemented onto Ti-base abutments to receive a cemented crown; [UCLA-Ce]: UCLA abutments that received an overcast coping and a cemented crown. Volume measurements were performed to assess the internal misfit using silicone replica of the implant/abutment interface area threedimensionally reconstructed after microcomputed tomography (CT). Implant/crown systems were subjected to step-stress accelerated life testing (SSALT) in water. The use-level probability Weibull curves and reliability for a mission of 50,000 cycles at calculated stress at failure of 2,300, 3,300 and 4,300 MPa were plotted. Fractographic analysis was performed with scanning electron microscopy. Internal misfit was analyzed through one-way ANOVA following post-hoc comparisons by Tukey test (P<0.05). Correlation between misfit volume and the stress at fatigue failure was assessed by Pearson test. Results. Similar misfit volumes were observed for TiB-Sc (0.458 mm3), TiB-Ce (0.461 mm3), UCLA (0.471 mm3) and UCLA-Ce (0.480 mm3), which were significantly lower than Digital-Sc (0.676 mm3) and Digital-Ce (0.633 mm3). The mean values were: 1.68, 1.39, 1.48, 2.41, 2.27 and 0.71 for Digital-Sc, TiB-Sc, UCLA, Digital-Ce, TiB-Ce and UCLA-Ce, respectively, indicating that fatigue was an accelerating factor for failure of all groups, except for UCLA-Ce. Higher stress at failure decreased the reliability of all groups, more significantly for screw compared to cement-retained groups, especially for Digital-Sc that demonstrated the lowest reliability. The failure mode was restricted to abutment screw fracture. A negative correlation was observed between misfit values and stress at failure (r = -0.302, P=0.01). Conclusions. Ti-Base and UCLA abutments exhibited better internal fit at the implant/abutment interfaces compared to full commercial lab fabrication process (CAD-CAM custom abutments). An impairment of the mechanical resistance according to different levels of internal misfit was observed, since the higher the volume of misfit, the lower the stress at failure during fatigue. Probability of survival decreased at higher stress, especially for screw compared to cement-retained groups, and failures were confined to abutment screws
  • DOI: 10.11606/T.25.2019.tde-05102021-142059
  • Editor: Biblioteca Digital de Teses e Dissertações da USP; Universidade de São Paulo; Faculdade de Odontologia de Bauru
  • Data de criação/publicação: 2019-08-20
  • Formato: Adobe PDF
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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