Biomechanical stress and microgap analysis of bone-level and tissue-level implant abutment structure according to the five different directions of occlusal loads

Abstract

PURPOSE The stress distribution and microgap formation on an implant abutment structure was evaluated to determine the relationship between the direction of the load and the stress value. MATERIALS AND METHODS Two types of three-dimensional models for the mandibular first molar were designed: bone-level implant and tissue-level implant. Each group consisted of an implant, surrounding bone, abutment, screw, and crown. Static finite element analysis was simulated through 200 N of occlusal load and preload at five different load directions: 0, 15, 30, 45, and 60°. The von Mises stress of the abutment and implant was evaluated. Microgap formation on the implant-abutment interface was also analyzed. RESULTS The stress values in the implant were as follows: 525, 322, 561, 778, and 1150 MPa in a bone level implant, and 254, 182, 259, 364, and 436 MPa in a tissue level implant at a load direction of 0, 15, 30, 45, and 60°, respectively. For microgap formation between the implant and abutment interface, three to seven-micron gaps were observed in the bone level implant under a load at 45 and 60°. In contrast, a three-micron gap was observed in the tissue level implant under a load at only 60°. CONCLUSION The mean stress of bone-level implant showed 2.2 times higher than that of tissue-level implant. When considering the loading point of occlusal surface and the direction of load, higher stress was noted when the vector was from the center of rotation in the implant prostheses.

Fractal Dimension as a Tool for Assessment of Dental Implant Stability—A Scoping Review

“…One of the factors which determines the stress distribution around the implants is whether it’s a tissue level or a bone level implant. Various studies have shown that bone level implants have higher stress distribution around them as compared with tissue level implants [ 41 , 42 ] reducing early failure risks. The prosthetic design also has a bearing on implant stability.…”

Influence of Implant-Abutment Contact Surfaces and Prosthetic Screw Tightening on the Stress Concentration, Fatigue Life and Microgap Formation: A Finite Element Analysis

“…As reported in the literature, the use of an external hexagon implant may be considered as a failure-prone prosthetic solution, due to the higher vertical misfit, stress concentration, microgap formation and increased torque loss during long-term usage [2,4,7,15,31]. Several studies have used the finite element analysis (FEA) as a method to access the biomechanical response of a unitary implant-supported restoration [4,7,15,18,19,21,25,[31][32][33][34]. Despite the limitations of this investigation, the FEA may provide important information regarding simulated clinical performance, which could be of value to both clinicians and patients [9].…”

“…In addition, implant systems with higher amounts of contacting surfaces, between the implant and abutment, could present a more optimal connection [6]. As the stresses generated on implants in the posterior region are higher at the implantabutment interface [6], the masticatory forces could affect the settling of the abutment into the implant and a preload loss may occur with the incidence of occlusal loading [7,8]. Therefore, maximizing the amount of contacting surfaces at the implant-abutment interface can contribute to better stress distribution.…”

“…Therefore, maximizing the amount of contacting surfaces at the implant-abutment interface can contribute to better stress distribution. Nevertheless, other factors can also affect the stress distribution of an implant-supported restoration, such as crown height, implant connection, load direction, cusp inclination, occlusal anatomy, and implant position [7].…”

“…To assess both stress and microgap formation, the finite element analysis can be applied as a biomechanical tool to study the implant-supported restoration [7,14]. According to the literature, there is a valid comparison between the in vitro measurements of the implantabutment microgaps and the in-silico simulations when considering similar boundary conditions [14][15][16].…”