Effects of Positions and Angulations of Titanium Dental Implants in Biomechanical Performances in the All-on-Four Treatment: 3D Numerical and Strain Gauge Methods

Abstract

In finite element (FE) simulations, the peak bone stresses were higher when loading with a cantilever extension (CE) than when loading without a CE by 33–49% in the cortical bone. In the in vitro experiments, the highest values of principal strain were all within the range of the minimum principal strain, and those peak bone strains were 40–58% greater when loading with a CE than when loading without a CE (p < 0.001). This study investigated how varying the implanted position and angulation of anterior implants in the All-on-Four treatment influenced the biomechanical environment in the alveolar bone around the dental implants. Ten numerical simulations of FE models and three in vitro samples of All-on-Four treatment of dental implants were created to investigate the effects of altering the implanted position and angulation type of anterior implants. A single load of 100 N was applied in the molar region in the presence or absence of a CE of the denture. The 3D FE simulations analyzed the von-Mises stresses in the surrounding cortical bone and trabecular bone. For the in vitro tests, the principal bone strains were recorded by rosette strain gauges and statistically evaluated using the Mann–Whitney U test and the Kruskal–Wallis test. Loading in the presence of a CE of the denture induced the highest bone stress and strain, which were 53–97% greater in the FE simulation and 68–140% in the in vitro experiments (p < 0.008) than when loading without a CE. The bone stresses in the FE models of various implanted positions and angulation types of anterior implants were similar to those in the model of a typical All-on-Four treatment. In vitro tests revealed that the bone strains were significantly higher in the samples with various angulation types of anterior implants (p < 0.008). In the All-on-Four treatment of dental implants, the bone stress and strain were higher when the load was applied to the CE of dentures. Altering the position or angulation of the anterior dental implant in the All-on-Four treatment has no benefit in relieving the stress and strain of the bone around the dental implant.

Influence of Framework Material and Posterior Implant Angulation in Full-Arch All-on-4 Implant-Supported Prosthesis Stress Concentration

“…Higher stress magnitude was observed in the mesial screws, agreeing with other studies [ 10 , 17 , 18 , 20 ] and showing similarity to the result found in the bone where tensile stress was higher in the region of the mesial implants. This can be justified because it is a more distant position of the cantilever that undergoes movement during the application of load in this region, functioning as a lever system.…”

“…During the distal implant installation, different angulation can be used according to surgical planning. However, the literature is not concise regarding the benefits of 30° and 45° angulation for reducing stress concentration [ 16 , 17 ]. It is important to note that the surgeon inserted inclined distal implants to reduce the cantilever length, and this variable should be considered when analyzing prosthetic modality.…”

Biomechanical Analysis of Titanium Dental Implants in the All-on-4 Treatment with Different Implant–Abutment Connections: A Three-Dimensional Finite Element Study

“…From a bioengineering perspective, a critical concern with this treatment is minimizing peak bone stress resulting from occlusal loading [22]. Many studies have focused on the effects of the cantilever length [23,24], position, and angulation of posterior implants [25,26]. However, the biomechanical performance of different implant-abutment connections in the mandibular all-on-4 treatment remains unclear.…”

The effect of different bone level and prosthetic connection on the biomechanical response of unitary implants: Strain gauge and finite element analyses

“…Associated with the strain gauge analysis, they allow the evaluation of complex situations with a valid model. [23][24][25] In view of the above, the present study aimed to evaluate, in silico and in vitro, the stress distribution and strain of unitary implants with different prosthetic connections and bone height. The hypothesis of the study consisted that prosthetic connection and bone height would not influence the mechanical response under axial load.…”