Influence of implant-abutment angulations and crown material on stress distribution on central incisor: a 3D FEA

Abstract

Aim: To investigate the effect of implant-abutment angulation and crown material on stress distribution of central incisors. Finite element method was used to simulate the clinical situation of a maxillary right central incisor restored by two different implant-abutment angulations, 15° and 25°, using two different crown materials (IPS E-Max CAD and zirconia). Methods: Two 3D finite element models were specially prepared for this research simulating the abutment angulations. Commercial engineering CAD/CAM package was used to model crown, implant abutment complex and bone (cortical and spongy) in 3D. Linear static analysis was performed by applying a 178 N oblique load. The obtained results were compared with former experimental results. Results: Implant Von Mises stress level was negligibly changed with increasing abutment angulation. The abutment with higher angulation is mechanically weaker and expected to fail at lower loading in comparison with the steeper one. Similarly, screw used with abutment angulation of 25° will fail at lower (about one-third) load value the failure load of similar screw used with abutment angulated by 15°. Conclusions: Bone (cortical and spongy) is insensitive to crown material. Increasing abutment angulation from 15° to 25°, increases stress on cortical bone by about 20% and reduces it by about 12% on spongy bone. Crown fracture resistance is dramatically reduced by increasing abutment angulation. Zirconia crown showed better performance than E-Max one.

Angulated Dental Implants in Posterior Maxilla FEA and Experimental Verification

“…Finally, the results of this study were in agreement with the literature [ 9 , 10 , 13 , 17 ] when abutments with 0, 15°, and 25° angulations were evaluated in the maxilla by 3D FEA, that the implants were recommended to be vertically aligned with axial loads.…”

“…That was reflected in cortical bone stress. Vertical implant transferred less - load to cortical bone (of order 22 MPa) by about 66% in comparison to angulated one (of order 67 MPa), while both cases showed stress levels within the physiological limits [ 9 ][ 10 ].…”

“…In previous studies [ 9 ][ 10 ][ 13 ] influence of implant - abutment angulations on stress distribution on central incisor were investigated. The conclusion of these studies was; cortical and spongy bone were insensitive to the crown material, and increasing abutment angulation from 15° to 25°, increases stress on cortical bone by about 20% and reduces it by about 12% on spongy bone.…”

“…Majority of finite element models in dental researchers [ 9 ][ 14 ] assumed perfect bond between assembled model components to simulate natural condition, in addition to assuming linear, static and isotropic material properties. The trend of the presence of higher Von Mises stresses in the bone around the angulated implant than bone around the straight implant did not differ by the bone levels [ 9 ][ 14 ]. Prominently, the highest level of stress was exhibited in the stepped area of the bones.…”

Correlation between abutment angulation and off-axial stresses on biomechanical behavior of titanium and zirconium implants in the anterior maxilla: A three-dimensional finite element analysis study

“…[ 17 ] Cone beam computed tomography-guided implant placement in the anterior maxilla will overcome the possibility of an angulated abutments, yet expensive; hence, its use can be restricted to place multiple implants in the same region. [ 35 36 37 38 ] Therefore, further studies can be carried out with improvements made to finite element models with respect to geometry of implants with regard to thread pitch, thread shape, and thread depth, applying dynamic loading conditions depending on the clinical situation.…”