The Effect of Three Different Crown Heights and Two Different Bone Types on Implants Placed in the Posterior Maxilla: Three-Dimensional Finite Element Analysis

Abstract

The purpose of this study was to determine the amount and localization of functional stresses in implants placed in two different bone types (type 3 and type 4) with three different crown heights in the atrophic posterior maxilla using finite element analysis. Materials and Methods: A three-dimensional finite element model of the posterior maxilla was created from a computerized tomography image by using the Marc 2005 (MSC Software) program. Three different crown/implant ratios (1/1, 1.5/1, 2/1) in the first molar tooth zone were modeled. Type 3 and type 4 bone quality according to the classification system of Lekholm and Zarb was created. The total oblique force of 300 N with a 30-degree angle was applied from the locations of the mesiobuccal cusp (150 N) and the distobuccal cusp (150 N) of first molar teeth. Results: For the implants, the highest stresses were observed around the implant neck at the crown/implant ratio of 2/1 (430.57 MPa). As the crown/implant ratio increased two times, the von Mises stresses increased at a rate of 47%. The highest tensile values exceeded the ultimate tensile strength of the cortical bone for all the designs. Also, the highest compressive values exceeded the ultimate compressive strength of the cortical bone in the 2/1 design for type 3 bone, and in the 1.5/1 and 2/1 designs for type 4 bone. As the crown/implant ratio increased from 1/1 to 2/1, the highest tensile value and the highest compressive value increased 13%. For the spongious bone, as the crown/implant ratio increased, the highest tensile value increased 42% and 85%, respectively. Tensile stresses increased at a rate of 26% in the 1/1 ratio, 30% in the 1.5/1 ratio, and 32% in the 2/1 ratio when the density of spongious bone decreased. Compressionrelated values also increased 34% in the 1/1 ratio, 35% in the 1.5/1 ratio, and 36% in the 2/1 ratio when the density of spongious bone decreased. Conclusion: Compressive and tensile stresses formed mostly at the alveolar bone around the implant neck that was cortical bone. Thus, it had to be preserved during the surgical procedures. Deformation due to the stresses had great importance for the type IV spongious bone due to the increase caused by the higher crown height levels.

The Influence of the Crown-Implant Ratio on the Crestal Bone Level and Implant Secondary Stability: 36-Month Clinical Study

“…In contrast, when the cantilever was not used, the MBL is independent from the C / I ratio [ 28 ]. Using the finite element method, it was demonstrated that the stress concentration and stress distribution increase with the height of the crown [ 29 , 30 ]. As the C / I ratio increased twice, the von Mises stresses rose by about 47%.…”

“…As the C / I ratio increased twice, the von Mises stresses rose by about 47%. At the C / I ratio of 2/1, the highest stresses were observed around the implant neck [ 29 ].…”

Evaluation of The Stress Distribution on Four Different Peri Implant Bone Types When Loaded with Three Different Implant Lengths Subjected to Vertical and Oblique Forces in the Mandible: A Three-Dimensional Finite Element Analysis

“…However, published data on stress patterns around implants of different lengths on surrounding bone are few. Whenever an implant is loaded, the load is transferred to the abutment, which carries it to the fixture and through the implant abutment and implant bone connection to the surrounding peri-implant bone [3]. Therefore, in the present study we aim to examine the role of implant height on stress and strain distribution patterns within the implant system and surrounding peri-implant bone.…”

Biomechanical analysis of different implant-abutments interfaces in different bone types: An in silico analysis

“…Clinically, low-density bone is associated with reduced implant survival rates compared to those bone of normal-density [8]. With other biomechanical studies having found no correlation between bone density and stress distribution, however, consensus remains unresolved [3,9].…”