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Effect of Misfit at Implant-Level Framework and Supporting Bone on Internal Connection Implants: Mechanical and Finite Element Analysis
Malmö University, Faculty of Odontology (OD).ORCID iD: 0000-0002-2893-3676
Malmö University, Faculty of Odontology (OD).ORCID iD: 0000-0002-9144-3442
Malmö University, Faculty of Odontology (OD).
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2019 (English)In: International Journal of Oral & Maxillofacial Implants, ISSN 0882-2786, E-ISSN 1942-4434, Vol. 34, no 2, p. 320-328Article in journal (Refereed) Published
Abstract [en]

Purpose: To evaluate the effect of misfit at implant-level fixed partial dentures (ILFPDs) and marginal bone support on the generation of implant cracks. Materials and Methods: This in vitro study included a mechanical fatigue test and finite element analysis. A mechanical cycling loading test was performed using 16 experimental models, each consisting of two parallel implants subdivided into four groups based on the misfit and the supporting bone condition. The framework, firmly seated at implants, was dynamically loaded vertically with a force of 1,600/160 N and 15 Hz for 1 × 106 cycles. Optical microscope, scanning electron microscope (SEM), and computed tomography three-dimensional (CT-3D) analyses were performed to detect impairments. Finite element models, representing the setups in the mechanical fatigue test, were used to represent the fatigue life. Results: None of the mechanical components presented distortion or fracture at the macroscopic level during the test. In a microscopy evaluation, the fatigue test revealed scratches visible in the inner part of the conical portion of the implants regardless of the groups. SEM and CT-3D analysis revealed one implant from the misfit/no bone loss group with a microfracture in the inner part of the conical interface. The simulated effective stress levels in the coronal body were higher in the misfit groups compared with the no misfit groups. The misfit groups presented effective stress levels, above 375 MPa, that penetrated the entire wall thickness. The no bone loss group presented an effective stress level above 375 MPa along its axial direction. In the no misfit group, the area presenting effective stress levels above 375 MPa in the conical connection was larger for the bone loss group compared with the no bone loss group. Conclusion: This study confirmed that implant fracture is an unlikely adverse event. A clear pattern of effective distribution greater than fatigue limit stresses could be noticed when the misfit was present. The dynamic load simulation demonstrated that the crack is more likely to occur when implants are fully supported by marginal bone compared with a bone loss scenario. Within the limitations of this study, it is speculated that marginal bone loss might follow the appearance of an undetected crack. Further research is needed to develop safe clinical protocols with regard to ILFPD.

Place, publisher, year, edition, pages
Quintessence , 2019. Vol. 34, no 2, p. 320-328
Keywords [en]
Alveolar Bone Loss, Biomechanical Phenomena, Dental Implants, Dental Prosthesis, Implant-Supported, Dental Stress Analysis, Denture, Partial, Fixed, Finite Element Analysis, Humans, Prosthesis Failure, Prosthesis Fitting, Stress, Mechanical
National Category
Dentistry
Identifiers
URN: urn:nbn:se:mau:diva-6640DOI: 10.11607/jomi.6965ISI: 000506575300006PubMedID: 30883615Scopus ID: 2-s2.0-85063279606Local ID: 30471OAI: oai:DiVA.org:mau-6640DiVA, id: diva2:1403585
Available from: 2020-02-28 Created: 2020-02-28 Last updated: 2024-02-05Bibliographically approved
In thesis
1. On Clinical and Mechanical Aspects in Implant Supported Screw Retained Multi-unit CAD-CAM Metal Framework
Open this publication in new window or tab >>On Clinical and Mechanical Aspects in Implant Supported Screw Retained Multi-unit CAD-CAM Metal Framework
2020 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Conventionally casted frameworks have been considered the preferredsolutions for complete and partial restorations since the beginningof implantology. However, following technological development, thecomputer aided design/computer aided manufacturing (CAD-CAM)with milling the frameworks has been introduced as an alternativeoption with the potential of minimising inaccuracies, reducing theoperator dependence and offering a homogeneous structure with highmechanical properties. The CAD-CAM multi-unit reconstructionvaries with fixation type, implant framework connection, andprostheses material. However, the materials developed for theuse of CAD-CAM, may have different technical and biologicalcomplications with time.The present thesis aims to provide insights into the risk ofcomplications in screw-retained multi-unit frameworks manufacturedusing the CAD-CAM technique. An in vitro test (Study I) was performed to assess the effectsof misfit at implant-level FPDs and supporting bone levels on thegeneration of implant cracks. Three clinical studies were conducted:in Study II, partially edentulous patients were rehabilitated with eitheran abutment or implant level multi-unit Cobalt-Chromium metalceramicframework; in Study III, patients, edentulous in the maxilla,were treated with either four or six implants and rehabilitated witha fixed titanium metal-acrylic framework; in Study IV edentulouspatients were treated with removable overdentures retained bytitanium milled bars. In Study III and IV, Oral Health Related Qualityof Life was evaluated.The marginal bone level change was clinically not significantregardless of fixation type (Study II), retention (Study III-IV), andmaterial used (Study II-III-IV). No framework complications wereregistered. Patients reported a high level of satisfaction after thetreatment (Study III-IV).

Based on the studies included in this thesis, the followingconclusions can be made: (i) the risk of implant cracks in screwretainedImplant Level (IL) Fixed Partial Denture (FPD) is low, evenwith a misfit; (ii) according to the 1-year data presented in Study II,abutment level (AL) retention is recommended for FPDs; (iii) the costeffectivefor a maxillary Fixed Complete Denture (FCD) supported byfour implants can be considered predictable and comparable to siximplants; (iv) implant-supported FCDs and Implant supported Over-Dentures (IOD) are associated with high rates of patient satisfaction,related to aesthetics and mastication function mainly resulting fromthe high stability of the prostheses; (v) the technical and biologicalcomplications reported in FPDs, FCDs and IODs were limited.However, a considerable percentage of prosthetic fractures andchippings were reported for FCDs at 1-year and 3-year follow-ups.Clinicians have to be aware that additional visits may be required formaintaining the prostheses.

Place, publisher, year, edition, pages
Malmö: Malmö universitet, 2020. p. 239
Series
Doctoral Dissertation in Odontology
National Category
Dentistry
Identifiers
urn:nbn:se:mau:diva-17386 (URN)10.24834/isbn.9789178770816 (DOI)9789178770809 (ISBN)9789178770816 (ISBN)
Available from: 2020-05-29 Created: 2020-05-29 Last updated: 2023-11-01Bibliographically approved

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Toia, MarcoStocchero, MicheleJinno, YoheiWennerberg, AnnBecktor, Jonas PJimbo, Ryo

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