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.
Highlights
Received for publication: November 15, 2015 Accepted: December 13, 2015Correspondence to: Mohamed I
Spongy bone Von Mises stress distribution with different abutment angulation is in Figure 4, where the spongy bone showed lower values with increasing abutment angulation
In a recent clinical report[18], elimination of veneered porcelain on posterior zirconia crowns and fixed dental prostheses was performed for a clinical trial and presented an acceptable esthetic result
Summary
Received for publication: November 15, 2015 Accepted: December 13, 2015. Dental implant restoration has been widely accepted as one of the treatment modalities to replace missing teeth and restore human masticatory function. The biomechanical properties of the bone–implant interface determine the implant stability. The bone–implant interface properties depend on amount of implant surface in contact with mineralized bone tissue and bone tissue quality around the interface[1]. The interface has a complex biomechanical nature due to (i) its roughness, (ii) the fact that bone is in partial contact with the implant, (iii) adhesion phenomena between bone and the implant and (iv) the time-evolving nature of the interface properties. Remodeling phenomena of bone tissue around the interface are difficult and highly complicated
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