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Stress distribution on different bar materials in implant-retained palatal obturator.

ABSTRACT: Implant-retained custom-milled framework enhances the stability of palatal obturator prostheses. Therefore, to evaluate the mechanical response of implant-retained obturator prostheses with bar-clip attachment and milled bars, in three different materials under two load incidences were simulated. A maxilla model which Type IIb maxillary defect received five external hexagon implants (4.1 x 10 mm). An implant-supported palatal obturator prosthesis was simulated in three different materials: polyetheretherketone (PEEK), titanium (Ti:90%, Al:6%, V:4%) and Co-Cr (Co:60.6%, Cr:31.5%, Mo:6%) alloys. The model was imported into the analysis software and divided into a mesh composed of nodes and tetrahedral elements. Each material was assumed isotropic, elastic and homogeneous and all contacts were considered ideal. The bone was fixed and the load was applied in two different regions for each material: at the palatal face (cingulum area) of the central incisors (100 N magnitude at 45°); and at the occlusal surface of the first left molar (150 N magnitude normal to the surface). The microstrain and von-Mises stress were selected as criteria for analysis. The posterior load showed a higher strain concentration in the posterior peri-implant tissue, near the load application side for cortical and cancellous bone, regardless the simulated material. The anterior load showed a lower strain concentration with reduced magnitude and more implants involving in the load dissipation. The stress peak was calculated during posterior loading, which 77.7 MPa in the prosthetic screws and 2,686 ?? microstrain in the cortical bone. For bone tissue and bar, the material stiffness was inversely proportional to the calculated microstrain and stress. However, for the prosthetic screws and implants the PEEK showed higher stress concentration than the other materials. PEEK showed a promising behavior for the bone tissue and for the integrity of the bar and bar-clip attachments. However, the stress concentration in the prosthetic screws may represent an increase in failure risk. The use of Co-Cr alloy can reduce the stress in the prosthetic screw; however, it increases the bone strain; while the Titanium showed an intermediate behavior.

SUBMITTER: Villefort RF

PROVIDER: S-EPMC7598468 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Stress distribution on different bar materials in implant-retained palatal obturator.

Villefort Regina Furbino RF Tribst João Paulo Mendes JPM Dal Piva Amanda Maria de Oliveira AMO Borges Alexandre Luiz AL Binda Nívia Castro NC Ferreira Carlos Eduardo de Almeida CEA Bottino Marco Antonio MA von Zeidler Sandra Lúcia Ventorim SLV

PloS one 20201030 10

Implant-retained custom-milled framework enhances the stability of palatal obturator prostheses. Therefore, to evaluate the mechanical response of implant-retained obturator prostheses with bar-clip attachment and milled bars, in three different materials under two load incidences were simulated. A maxilla model which Type IIb maxillary defect received five external hexagon implants (4.1 x 10 mm). An implant-supported palatal obturator prosthesis was simulated in three different materials: polye ...[more]

PMID: 33125441

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Project description:BackgroundLong-term success of implant restoration depends on many factors one of them is the sufficient implant stability which is lowered in compromised bone density sites such as the maxilla as it is categorized as type III & IV bone, so searching for a new innovation and updates in implant material and features is very mandatory. So, the aim of this study was to compare between two implant materials (roxolid and traditional titanium) on the primary and secondary stability of implant retained maxillary overdenture.MethodsEighteen completely edentulous patients were selected. All patients received maxillary implant-retained overdentures and lower complete dentures; patients were divided equally into two groups according to the type of implant materials. Group A received a total number of 36 implants made of roxolid material and Group B received a total number of 36 implants made of traditional titanium alloys. Implant stability was assessed using ostell device, the primary implant stability was measured at the day of implant installation however, secondary implant stability was measured after six weeks of implant placement. Paired t-test was used to compare between primary and secondary stability in the same group and an independent t-test was used to compare between the two groups with a significant level < 0.05.ResultsIndependent t-test revealed a significant difference between the two groups with p -value = 0.0141 regarding primary stability and p-value < 0.001 regarding secondary stability, as roxolid implant group was statistically higher stability than titanium group in both. Paired t- test showed a statistically significant difference in roxolid implant group with p-value = 0.0122 however, there was non-statistically significant difference in titanium group with p-value = 0.636. Mann Whitney test showed a significant difference between the two groups regarding amount of change in stability with p value = 0.191. roxolid implant group showed a higher amount of change in stability than the titanium implant group.ConclusionWithin the limitation of this study, it could be concluded that: Roxolid implants showed promising results regarding primary and secondary stability compared to conventional Titanium implants and can be a better alternative in implant retained maxillary overdentures.Trial registrationRetrospectively NCT06334770 at 26-3-2024.

Project description:Background/objectiveUntil 2010, adults underwent surgical treatment for maxillary expansion; however, with the advent of micro-implant-assisted rapid maxillary expansion (MARME), the availability of less invasive treatment options has increased. Nevertheless, individuals with severe transverse maxillary deficiency do not benefit from this therapy. This has aroused interest in creating a new device that allows the benefit of maxillary expansion for these individuals. The aim of this study was to evaluate the efficacy of three MARME models according to tension points, force distribution, and areas of concentration in the craniofacial complex when transverse forces are applied using finite element analysis.Materials and methodsDigital modeling of the three MARME models was performed. Model A comprised five components: one body screw expander and four adjustable arms with rings for mini-implant insertion. These arms have an individualized height adjustment that allows MARME positioning according to the patient's palatal anatomy, thereby preventing body screw expander collision with the lateral mucosa in severe cases of maxillary deficiency. Model B was a maxillary expander with screw rings joined to the body, and model C was similar to model B, except that model C had open rings for the insertion of the mini-implants. Through the MEF (Ansys software), the stresses, distribution, and area of concentration of the stresses were evaluated when transverse forces of 7.85 N were applied.ResultsThe three models maintained the following pattern: model C presented weak stress peaks with limited distribution and lower concentration area, model B obtained median stress peaks with better distribution when compared to that of model C, and model A showed better stress distribution and larger concentration area. In model A, tensions were located in the lateral lamina of the pterygoid process, which is an important site for maxillary expansion. The limitation of the present study was that it did not include the periodontal tissues and muscles in the finite element method evaluation.ConclusionsModel A showed the best stress distribution conditions. In cases of severe atresia, model A seems to be an excellent option.

Dataset Information

Stress distribution on different bar materials in implant-retained palatal obturator.

Publications

Stress distribution on different bar materials in implant-retained palatal obturator.

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