Tilted and Short Implants Supporting Fixed Prosthesis in an Atrophic Maxilla: A 3D-FEA Biomechanical Evaluation

Purpose: This study compared the biomechanical behavior of tilted long implant and vertical short implants to support fixed prosthesis in an atrophic maxilla. Materials and Methods: The maxilla model was built based on a tomographic image of the patient. Implant models were based on micro-computer tomography imaging of implants. The different configurations considered were M4S, four vertical anterior implants; M4T, two mesial vertical implants and two distal tilted (45°) implants in the anterior region of the maxilla; and M6S, four vertical anterior implants and two vertical posterior implants. Numerical simulation was carried out under bilateral 150N loads applied in the cantilever region in axial (L1) and oblique (45°) (L2) direction. Bone was analyzed using the maximum and minimum principal stress (σmax and σmin), and von Mises stress (σvM) assessments. Implants were analyzed using the σvM. Results: The higher σmax was observed at: M4T, followed by M6S/L1, M6S/L2, M4S/L2, and M4S/L1 and the higher σvM: M4T/L1, M4T/L2 and M4S/L2, M6S/L2, M4S/L1, and M6S/L1. Conclusions: The presence of distal tilted (all-on-four) and distal short implants (all-on-six) resulted in higher stresses in both situations in the maxillary bone in comparison to the presence of vertical implants (all-on-four). © 2013 Wiley Periodicals, Inc.

Avaliação da influência da força de mordida na prótese parcial removível classe I mandibular associada ao implante osseointegrado, pelo método dos elementos finitos

Pós-graduação em Odontologia - FOA

Análise da influência dos sistemas de retenção para overdentures implanto-retidas e da espessura e resiliência da fibromucosa na distribuição interna das tensões, através do método de elementos finitos bidimensional

Pós-graduação em Odontologia - FOA

Influence of Platform and Abutment Angulation on Peri-Implant Bone. A Three-Dimensional Finite Element Stress Analysis

The aim of this study was to evaluate stress distribution on the pen-implant bone, simulating the influence of Nobel Select implants with straight or angulated abutments on regular and switching platform in the anterior maxilla, by means of 3-dimensional finite element analysis. Four mathematical models of a central incisor supported by external hexagon implant (13 mm x 5 mm) were created varying the platform (R, regular or S. switching) and the abutments (S, straight or A, angulated 15 degrees). The models were created by using Mimics 13 and Solid Works 2010 software programs. The numerical analysis was performed using ANSYS Workbench 10.0. Oblique forces (100 N) were applied to the palatine surface of the central incisor. The bone/implant interface was considered perfectly integrated. Maximum (sigma(max)) and minimum (sigma(min)) principal stress values were obtained. For the cortical bone the highest stress values (sigma(max)) were observed in the RA (regular platform and angulated abutment, 51 MPa), followed by SA (platform switching and angulated abutment, 44.8 MPa), RS (regular platform and straight abutment, 38.6 MPa) and SS (platform switching and straight abutment, 36.5 MPa). For the trabecular bone, the highest stress values (sigma(max)) were observed in the RA (6.55 MPa), followed by RS (5.88 MPa), SA (5.60 MPa), and SS (4.82 MPa). The regular platform generated higher stress in the cervical periimplant region on the cortical and trabecular bone than the platform switching, irrespective of the abutment used (straight or angulated).

Eight-Year Follow-Up of a Fixed-Detachable Maxillary Prosthesis Utilizing an Attachment System: Clinical Protocol for Individuals With Skeletal Class III Malocclusions

The aim of this article is to describe a successful clinical protocol for prosthodontic rehabilitation of a patient with a skeletal Class III malocclusion using a fixed-detachable maxillary prosthesis supported by 6 implants and the MK1 attachment system. The patient was followed up for 8 years. A 46-year-old edentulous woman with a skeletal Class III malocclusion expressed dissatisfaction with her old existing maxillary denture from an esthetic point of view and frustration regarding its function. A fixed-detachable maxillary prosthesis using the MK1 attachment system was made. The patient was followed up clinically and radiographically for 8 years. No bone loss, fracture of prosthetic components, or fracture of the prosthesis was detected in that period. A fixed detachable maxillary prosthesis using the MK1 attachment system is a treatment option for patients with Class III malocclusions who opt not to undergo orthognathic surgery.

Análise das tensões em próteses implantossuportadas esplintadas, variando a localização dos implantes, pôntico e cantilever: estudo pelo método dos elementos finitos tridimensionais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Bone-implant contact around crestal and subcrestal dental implants submitted to immediate and conventional loading

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

The effect of offset implant configuration on bone stress distribution: a systematic review

Purpose: The aim of this systematic review was to compare straight-line and offset implant configurations for three-element implant-retained prostheses. Materials and Methods: Two independent reviewers conducted a review on PubMed/Medline, EMBASE, and Cochrane Library for studies published in English, from January 1, 1995 to January 17, 2014. A systematic review was conducted following the PRISMA statement. All relevant titles were selected according to inclusion/exclusion criteria. From this pool of titles, abstracts and full texts were reviewed. Results: A total of 6080 titles were identified with the initial search. Twenty-one were selected based on title and abstract. Of these, after discussion and complete reading, 12 studies were selected according to the inclusion and exclusion criteria, all of which were in vitro studies. Conclusions: A systematic review of the current literature showed only in vitro evidence that there is no consensus on the advantage of using an offset configuration implant compared to those in straight-line configuration, even though some studies present a slight improvement of bone stress distribution when an offset implant is under oblique loading (PICO).

The fitness of copings constructed over UCLA abutments and the implant, constructed by different techniques: casting and casting with laser welding

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A 3-D finite element study of the influence of crown-implant ratio on stress distribution

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Photoelastic stress analysis in prosthetic implants of different diameters: mini, narrow, standard or wide

This study investigated the biomechanical behavior of screwed partial fixed prosthesis supported by implants with different diameters (2.5 mm; 3.3 mm and 3.75 mm) by using a photoelastic analysis. Six photoelastic models were fabricated in PL-2 resin as single crowns or splinted 3-unit piece. Models were positioned in a circular polariscope and 100-N axial and oblique (45 degrees) loads were applied in the occlusal surface of the crowns by using a universal testing machine (EMIC). The stresses were photographically recorded and qualitatively analyzed using a software (Adobe Photoshop). Under axial loading, the number of fringes was inversely proportional to the diameter of the implants in the single crown models. In the splinted 3-unit piece, the 3.75-mm implant promoted lower number of fringes regardless of loading area application. Under oblique loading, a slight increase of fringes number was observed for all groups. The standard implant diameter promoted better stress distribution than the narrow and mini diameter implants. Additionally, the splinted crowns showed a more uniform stress distribution.

Dynamic UCLA for single tilted implant in an aesthetic region

The aim of this paper was to present a rehabilitation of a patient with a dynamic universal castable long abutment (UCLA) for a single tilted implant in the anterior maxillary area. A 57-year-old male patient attended the dentistry college clinic complaining of a vertical fracture of a residual root of the dental element 22. The tooth extraction was indicated for the implant installation. Due to the socket buccal wall thickness, the implant was installed with an inclination to the palate. It was done in a two-stage surgical protocol, and an external hexagon implant (3.75×11.5mm) was placed. After a six-month healing period to correct the implant position, a dynamic UCLA was set in place, rectifying the implant emergence profile at 20°. The ceramic structure fitting was performed and, after the patient's consent, the prosthesis was finalized and installed. After a follow-up period of twenty months, no complications were observed. The installation of tilted implants with a dynamic UCLA may be a viable option, faster and less invasive than bone grafts.

Segmental osteotomy for the correction of a malpositioned single implant: an 8-year follow-up

This case report is an 8-year follow-up of a malpositioned single implant, which was treated with segmental osteotomy, to confirm the treatment's characteristics, indications, and advantages. Deep buccal positioning of an endosseous implant placed in the maxillary left central incisor area did not permit acceptable prosthetic rehabilitation, despite its favorable bone insertion with no significant marginal bone loss. The surgical procedure included osteotomy and block movement performed toward the lingual and cervical position, fixed with a provisional prosthesis and miniplates and mini-implants. A connective tissue graft was necessary for esthetics optimization and was performed in a second stage. Advantages including the prevention of alveolar ridge damage, the improvement of gingival contour, and the use of an already integrated implant are presented. Clinically satisfactory hard and soft tissue stability permitted us to consider segmental surgery as a reliable alternative for malpositioned osseointegrated implants.

Influence of crown-to-implant ratio, retention system, restorative material, and occlusal loading on stress concentrations in single short implants

Purpose: The aim of this study was to assess the contributions of some prosthetic parameters such as crown-to-implant (C/I) ratio, retention system, restorative material, and occlusal loading on stress concentrations within a single posterior crown supported by a short implant. Materials and Methods: Computer-aided design software was used to create 32 finite element models of an atrophic posterior partially edentulous mandible with a single external-hexagon implant (5 mm wide × 7 mm long) in the first molar region. Finite element analysis software with a convergence analysis of 5% to mesh refinement was used to evaluate the effects of C/I ratio (1:1; 1.5:1; 2:1, or 2.5:1), prosthetic retention system (cemented or screwed), and restorative material (metal-ceramic or all ceramic). The crowns were loaded with simulated normal or traumatic occlusal forces. The maximum principal stress (σmax) for cortical and cancellous bone and von Mises stress (σvM) for the implant and abutment screw were computed and analyzed. The percent contribution of each variable to the stress concentration was calculated from the sum of squares analysis. Results: Traumatic occlusion and a high C/I ratio increased stress concentrations. The C/I ratio was responsible for 11.45% of the total stress in the cortical bone, whereas occlusal loading contributed 70.92% to the total stress in the implant. The retention system contributed 0.91% of the total stress in the cortical bone. The restorative material was responsible for only 0.09% of the total stress in the cancellous bone. Conclusion: Occlusal loading was the most important stress concentration factor in the finite element model of a single posterior crown supported by a short implant.

Dental implant fractures: aetiology, treatment and case report

Purpose: This study aimed to investigate the etiology, clinical manifestations, and treatment options of dental implants fractures through a literature review and to relate a clinical report. Methods: A literature review was performed using the Medline database and this paper describes a case demonstrating the management of implant fracture. Twenty two articles were selected in the present literature review. Results: Nowadays the use of dental implants to rehabilitate completely and partially edentulous patients became the best treatment option; however, this treatment is suitable to failure. The fracture of implant body is a possible complication. The fracture of implant body is a late complication and is related to the failure in implant design or material, non-passive fitting of the prosthetic crown and overloading. Clinically, prosthesis instability and spontaneous bleeding are observed. Three options of treatment have been indicated: complete removal of implant fragment, maintenance of implant fragment, and surface preparation of the fragment with insertion of a new abutment. Conclusion: The literature indicates the complete removal of the fragment as the best treatment option.