Photoelastic analysis of all-on-four concept using different implants angulations for maxilla

Abstract

Conventional tilted implants are used in oral rehabilitation for heavily absorbed maxilla to avoid bone grafts; however, few research studies evaluate the biomechanical behavior when different angulations of the implants are used. The aim of this study was evaluate, trough photoelastic method, two different angulations and length of the cantilever in fixed implant-supported maxillary complete dentures. Two groups were evaluated: G15 (distal tilted implants 15°) and G35 (distal tilted implants 35°) n = 6. For each model, 2 distal tilted implants (3.5 x 15 mm long cylindrical cone) and 2 parallel tilted implants in the anterior region (3.5 x 10 mm) were installed. Photoelastic models were submitted to three vertical load tests: in the end of cantilever, in the last pillar and in the all pillars at the same time. We obtained the shear stress by Fringes software and found values for total, cervical and apical stress. The quantitative analysis was performed using the Student tests and Mann-Whitney test; p ≥ 0.05. There is no difference between G15 and G35 for total stress regardless of load type. Analyzing the apical region, G35 reduced strain values considering the distal loads (in the cantilever p = 0.03 and in the last pillar p = 0.02), without increasing the stress level in the cervical region. Considering the load in all pillars, G35 showed higher stress concentration in the cervical region (p = 0.04). For distal loads, G15 showed increase of tension in the apical region, while for load in all pillars, G35 inclination increases stress values in the cervical region.

Previsibilidade de reabilitações de maxilas edêntulas com a técnica all-on-four: revisão de literatura

“…Os estudos in vitro de Bellini e Taschieri 19 (2009), Cidade et al 20 (2014), Saber et al 21 (2015), Gümrükçü et al 22 (2017) analisaram a previsibilidade de sucesso das reabilitações através das tensões encontradas em implantes e no tecido ósseo. Cidade et al 20 (2014), utilizando medidas fotoelásticas, avaliaram o comportamento biomecânico de implantes com diferentes angulações. Ao elevar a angulação de 15º para 35º em implantes distais, não houve diferença na tensão total, independentemente do tipo de carga recebida.…”

Implant and prosthesis survival rates of full‐arch immediate prostheses supported by implants with and without bicortical anchorage: Up to 2 years of follow‐up retrospective study

“…In comparison with implant rehabilitation without grafting, bone augmentation procedures carry a higher risk of patient morbidity and complications (e.g., infection, loss of graft material) as well as higher costs and longer treatment time and, thus, often present low patient acceptability (Agliardi et al, 2010;Cidade et al, 2014;Del Fabbro et al, 2004).…”

Mechanical properties of resin glass fiber-reinforced abutment in comparison to titanium abutment

“…The greater the angle of the force, relative to the axis of the implant body, the greater the resulting potential damage to the bony crest. [ 6 7 8 9 10 ]…”

“…The stress can be reduced by increasing the implant surface or decreasing the biomechanical forces that may be decreased in magnitude, duration, type, direction, and application. [ 6 12 ] Another possible method to reduce the stress at the crestal bone level is to use an abutment made of a flexible material that deforms within its elastic limit, absorbing a part of the load applied.…”