Abstract
BackgroundThe aim of this study was to evaluate the distribution of stress in complete fixed mandibular prostheses with infrastructures (IE) fabricated with different materials and techniques, under compressive force.Material and MethodsA model of an edentulous mandible, which received five 4x11 mm external hexagon implants between the mental foramens, was fabricated. The groups were divided into: Group I - IE in nickel-chromium with an acrylic resin occlusal coating; Group II – IE in nickel-chromium with a ceramic occlusal coating; Group III – IE milled in zirconia with a ceramic coating. For the photoelastic methodology, 70 N axial loads were applied in three regions. Photographic images were taken and analyzed according to the number of high-intensity fringes. For the strain gauge methodology, the measurement of stresses was performed in two distinct regions. The same compression tests described earlier were then performed. The registered stress values were grouped in tables and submitted to two-factor variance analysis (ANOVA) and the Tukey test with 5% significance.ResultsThe results of the two methodologies demonstrated smaller stress values for Group I, when compared to the other groups.ConclusionsIt was possible to conclude that the complete fixed prostheses, with infrastructures cast in metal and acrylic occlusal coating, demonstrated better biomechanical results. Key words:Dental implants, mandibular prosthesis implantation, biomechanics.
Highlights
Before the use of osseointegrated implants, the only available treatment option for fully edentulous patients was the complete muco-supported prosthesis.1 in some cases, even when executed well, the prosthesis does not totally restore the functional capacity of patients, due to the qualitative and quantitative reduction of masticatory efficiency [1]
The aim of this study was to evaluate the distribution of stress, by means of the photoelastic methodology and strain gauge, in complete fixed mandibular prostheses with infrastructures fabricated with different materials and techniques, submitted to the force of compression
It was observed that the prostheses with a metallic infrastructure and an aesthetic acrylic resin coating (GI) presented the smaller number of high intensity fringes, as demonstrated in Table 3 and in Figures 1 and 3
Summary
Before the use of osseointegrated implants, the only available treatment option for fully edentulous patients was the complete muco-supported prosthesis. in some cases, even when executed well, the prosthesis does not totally restore the functional capacity of patients, due to the qualitative and quantitative reduction of masticatory efficiency [1]. A Branemärk-type complete fixed mandibular prosthesis is a predictable and favorable treatment which restores functional capacity and presents a high rate of clinical success [4]. In this context, it could be considered the best form of rehabilitation for fully edentulous mandibles, based on patient satisfaction evaluations [5]. The frequent need to section and solder, to obtain a passive adaptation, is one of the disadvantages of this technique [6] To solve this problem, the great evolution in dental treatment is the use of the CAD/CAM (computer-aided design and computer-aided manufacturing) [7] principle of engineering, allowing milling of complete fixed prosthesis infrastructures in titanium, ceramic, and cobalt-chromium, aiming to provide the greatest adaptation possible [8]. The null hypothesis of this study is that there will be no difference in the distribution of stress between the conventional complete fixed prostheses and those milled in zirconia, and between the coating materials
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