Analysis of stress distribution in ceramic and titanium implants in alveolar sockets of the anterior region of the maxilla.

BACKGROUND: In the routine of dentistry, knowing the biomechanical properties of implant systems and their inherent stress distribution under force loading is an essential step to predict structural damage and biological responses. This study aimed to investigate stress distribution in zirconia and titanium implants and their biomechanical response in alveolar sockets of the anterior region of the maxilla through tridimensional finite element analysis. MATERIAL AND METHODS: From computed tomography scans of a reference patient, three models of the maxillary dental arch were designed with Rhinoceros 5.0 software (McNeel Europe™, Barcelona, Spain). In each model, a dental implant replaced the maxillary left central incisor. The implants consisted of M1) Zirconia Pure Ceramic Implant Monotype; M2) Zirconia Pure Ceramic ZLA; and M3) Titanium Bone Level - Roxolid SLA. Ceramic crowns were installed in all the implants. Implants and prostheses were loaded with 50N oblique and axial forces. Von-Mises and Mohr Coulomb criteria were used to assess stress distribution in the implant systems and perimplantar bone, respectively. RESULTS: Traction was detected in the cervical region of the palatal bone surface of all the models. Oppositely, compression was found in the cervical region of the vestibular bone surfaces. CONCLUSIONS: Zirconia Pure Ceramic Implant Monotype had the best response under oblique force loading. Ceramic implants may be an alternative to replace titanium implants in fresh alveolar sockets in the anterior region of the maxilla. Key words:Finite elements, implants, stress, ceramic, titanium.

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 peri-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 × 5 mm) were created varying the platform (R, regular or S, switching) and the abutments (S, straight or A, angulated 15°). 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 (σmax) and minimum (σmin) principal stress values were obtained. For the cortical bone the highest stress values (σmax) 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 (σmax) 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).

Influence of microthreads and platform switching on stress distribution in bone using angled abutments.

PURPOSE: To evaluate the stress distribution in peri-implant bone by simulating the effect of an implant with microthreads and platform switching on angled abutments through tridimensional finite element analysis. The postulated hypothesis was that the presence of microthreads and platform switching would reduce the stress concentration in the cortical bone. METHODS: Four mathematical models of a central incisor supported by an implant (5.0 mm × 13 mm) were created in which the type of thread surface in the neck portion (microthreaded or smooth) and the diameter of the angled abutment connection (5.0 and 4.1mm) were varied. These models included the RM (regular platform and microthreads), the RS (regular platform and smooth neck surface), the SM (platform switching and microthreads), and the SS (platform switching and smooth neck). The analysis was performed using ANSYS Workbench 10.0 (Swanson Analysis System). An oblique load (100N) was applied to the palatine surface of the central incisor. The bone/implant interface was considered to be perfectly integrated. Values for the maximum (σ(max)) and minimum (σ(min)) principal stress, the equivalent von Mises stress (σ(vM)), and the maximum principal elastic strain (ɛ(max)) for cortical and trabecular bone were obtained. RESULTS: For the cortical bone, the highest σ(max) (MPa) were observed for the RM (55.1), the RS (51.0), the SM (49.5), and the SS (44.8) models. The highest σ(vM) (MPa) were found for the RM (45.4), the SM (42.1), the RS (38.7), and the SS models (37). The highest values for σ(min) were found for the RM, SM, RS and SS models. For the trabecular bone, the highest σ(max) values (MPa) were observed in the RS model (6.55), followed by the RM (6.37), SS (5.6), and SM (5.2) models. CONCLUSION: The hypothesis that the presence of microthreads and a switching platform would reduce the stress concentration in the cortical bone was partially rejected, mainly because the microthreads increased the stress concentration in cortical bone. Only platform switching reduced the stress in cortical bone.