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.
Highlights
Before dental implants became popular, patients with complete edentulism could only receive conventional removable complete dentures for oral reconstruction
Two of the four implants are planted in the incisor zone, and another two implants are embedded in the molar region at angles from 18◦ to 45◦ to avoid the maxillary sinus [5] or the inferior alveolar nerve [6], which is the small branch of the third trigeminal nerve below the posterior jawbone area
Simulations, the peak bone stresses were higher when loading with a cantilever extension (CE) than when loading without a CE by 53–97% in the cortical bone (Tables 2 and 3)
Summary
Before dental implants became popular, patients with complete edentulism could only receive conventional removable complete dentures for oral reconstruction. Some functional problems can be experienced by elderly patients [1], such as needing more time for chewing and experiencing pain when chewing [2]. These aspects result in such patients only being able to masticate soft food, which impairs the quality of their daily living in terms of diet. According to the statistical study of Babbush et al [7], the All-on-Four treatment costs less, reduces the complexity of the treatment, and increases patient comfort relative to conventional implant treatment modalities
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