Biomechanical performance on narrow-diameter implants supports splinted and non-splinted prosthesis used in atrophic posterior maxilla in aging patient: a finite element analysis

The aim of this experimental study was to evaluate the stress distribution in periimplantcrestal bone on three implant models of category 2 (diameter 2.5 to 3.3 mm)and category 3 (diameter 2.5 to 3.3 mm) narrow diameters implant with splinted andnon-splinted crown in atrophic posterior maxilla in aging patients using the finiteelement analysis method (FEA).Materials and methodsTwo dental implants of category 3 narrow diameter (3.3 mm) restored with nonsplintedcrown (Regimen group; R group), two dental implants of category 2 narrowdiameter implants (3.0 mm) restored with non-splinted crown (Experimental 1; E1group) and two dental implants of category 2 narrow diameter (3.0 mm) restored withsplinted crown (Experimental 2; E2 group). A three-dimensional model was designed2022with cortical and cancellous bone, a crown and an implant/abutment set of eachgroup. Axial, oblique (30 ̊), and lateral (90 ̊) loads of 56.9 N was applied. The equivalentvon Mises stress was used for the implants and peri-implant bone microstrain wereevaluated by Frost’s mechanostat theory.ResultsIn the axial load, the von Mises stress value of NDIs for all groups were comparable.The lateral load showed highest von Mises stress value in R-10 group with 9.78-foldhigher than axial load, and 1.66 to 2.16-fold higher than that the oblique direction.However, there are no groups of study showed a value higher than the Ti-Zr materialyield strength limit.The stress analysis of elastic strain in axial load direction of all groups were within theadapted window (physiologic window) of Frost’s mechanostat theory, while the resultof oblique load was range in mild overload window, and lateral load result was rangein pathologic overload window. The elastic strain of axial load result was comparablein stress distribution of all group. However, in oblique load and lateral load, thesplinted crown group show the better result of elastic strain than non-splinted crowngroup, and this result was smaller than of the regimen group.Conclusionsthe narrow-diameter implant can be used to rehabilitation in upper posteriorarea of aging patients. The category 3 narrow-diameter implant (3.3 to 3.5 mm) andcategory 2 narrow-diameter implant (2.5 to <3.3 mm) can be used successfully inposterior maxilla area in meaning of axial load transmitted. However, the angle loadin narrow-diameter implants should be carefully considered together with otherbiomechanics relative factors. Additionally, the splinted crown can be helpful inconditions of angle load for better load sharing effect