Biomechanical behavior of overdentures supported by different implant position and angulation using Micro ERA® system: a finite element analysis study

Aim: The aim of this study was to investigate the biomechanical behavior of implant-retained mandibular overdentures using Micro ERA® system with different implant position and angulation by finite element analysis (FEA). Methods: Four 3D finite element models of simplified mandibular overdentures were constructed, using one Bränemark implant with a Micro ERA® attachment. The implant was positioned on the canine or lateral incisor area with an angulation of either 0º (C-0º; LI-0º) or 17º (C-17º, LI-17º) to the vertical axis. A 100 N axial load was applied in one side simultaneously, from first premolar to second molar. In all models it was analyzed the overdenture displacement, compressive/tensile stress in the bone-implant interface, and also the von Mises equivalent stress for the nylon component of the housing. The stresses were obtained (numerically and color-coded) for further comparison among all the groups. Results: The displacement on the overdenture was higher at the posterior surface for all groups, especially in the C-17º group. When comparing the compressive/tensile stress in the bone-implant interface, the lateral-incisor groups (LI-0º and LI-17º) had the highest compressive and lowest tensile stress compared to the canine groups (C-0º and C-17º). The von Mises stress on the nylon component generated higher stress value for the LI-0º among all groups. Conclusions: The inclination and positioning of the implant in mandibular overdenture interferes directly in the stress distribution. The results showed that angulated implants had the highest displacement. While the implants placed in the lateral incisor position presented lower compressive and higher tensile stress respectively. For the attachment the canine groups had the lowest stress

Análise de dois métodos de desinfecção de condutos radiculares após preparo para pinos: proposta de protocolo protético: estudo in vitro / Analysis of two methods of root canal disinfection after preparation for pins: proposal of prosthetic protocol: in vitro study

Introdução: Quando existe perda de suporte coronário e ainda desgaste adicional devido a tratamento endodôntico, muitas vezes, é necessária a utilização de um retentor intrarradicular que devolva a retenção para a restauração, reestabelecendo estética e função às estruturas dentárias perdidas. A cadeia asséptica mantida durante a endodontia pode ser quebrada com alguns procedimentos clínicos. Objetivo: Testar um protocolo de desinfecção por E. faecalis dos condutos radiculares, nas etapas de confecção de um retentor intrarradicular, desmistificando que a quebra da cadeia asséptica e o surgimento de infecções radiculares sejam provenientes da reabilitação protética. Material e método: 50 dentes unirradiculares com endodontia concluída foram desobturados, tiveram seus condutos preparados para retentor intrarradicular e foram contaminados por Enterococcus faecalis. Os dentes foram separados em três grupos de acordo com a substância desinfectante: G1-solução fisiológica (n=10), G2- hipoclorito de sódio 2,5% (n=20), G3- clorexidina 2% (n=20). Em seguida, foi feita a desinfecção do conduto, secagem e análise da eficácia da solução. A avaliação da presença da bactéria foi feita através do cultivo em caldo Brain Heart Infusion, pelo método da turvação, e posterior identificação pelo meio Ágar Bílis-Esculina. A análise estatística foi feita pelo método do quiquadrado em tabulação cruzada, onde p<0,0001. Resultado: Observou-se a inibição bacteriana de 100% em G2 e G3 e crescimento bacteriano de 100% em G1. Conclusão: O emprego das substâncias avaliadas nas etapas protéticas de finalização de um retentor intrarradicular, como protocolado por esta pesquisa, é capaz de manter a cadeia asséptica sem interferir no sucesso da reabilitação protética.

Introduction: When there is loss of the coronary supports and still further wear due to endodontic treatment, very often, it is necessary to use a intraradical retainer to restore aesthetics and function of lost dental structures. Within this rehabilitation, the aseptic chain which was maintained during endodontics can be broken using some clinical procedures. Aim: Test a disinfection protocol by E. faecalis of root canals, in the steps of making an intraradicular retainer, demystifying that the fracture of the aseptic chain and the emergence of root infections are coming from prosthetic rehabilitation. Materials and method: 50 single-rooted teeth with complete endodontics were unfilled, they had their conduits prepared for an intraradical retainer and contaminated by Enterococcus. faecalis. The teeth were divided into 3 groups according to the disinfectant solution. G1- saline (n= 10), G2 2.5% sodium hypochlorite (n=20), G3- chlorhexidine 2% (n=20). Then, a disinfection of conduit, drying and analysis of the efficacy of the solution was made. The evaluation of the presence of Enterococcus faecalis was made by cultivating in Brain Heart Infusion broth by the method of turbidity, and subsequent identification by means Agar Bile-Esculin. Statistical analysis were performed using the chi-square method in cross-tabulation, where p <0.0001. Result: As a result, it was observed 100% bacteria inhibition in G2 and G3, and bacterial growth of 100% in G1. Conclusion: The use of substances assessed in the prosthetic stages of finalizing an intraradical retainer, as filed by this research, is able to maintain the aseptic chain without interfering with success of prosthetic rehabilitation.