Biomechanical Analyses of Porous Designs of 3D-Printed Titanium Implant for Mandibular Segmental Osteotomy Defects

Abstract

Clinically, a reconstruction plate can be used for the facial repair of patients with mandibular segmental defects, but it cannot restore their chewing function. The main purpose of this research is to design a new three-dimensionally (3D) printed porous titanium mandibular implant with both facial restoration and oral chewing function reconstruction. Its biomechanical properties were examined using both finite element analysis (FEA) and in vitro experiments. Cone beam computed tomography images of the mandible of a patient with oral cancer were selected as a reference to create 3D computational models of the bone and of the 3D-printed porous implant. The pores of the porous implant were circles or hexagons of 1 or 2 mm in size. A nonporous implant was fabricated as a control model. For the FEA, two chewing modes, namely right unilateral molar clench and right group function, were set as loading conditions. Regarding the boundary condition, the displacement of both condyles was fixed in all directions. For the in vitro experiments, an occlusal force (100 N) was applied to the abutment of the 3D-printed mandibular implants with and without porous designs as the loading condition. The porous mandibular implants withstood higher stress and strain than the nonporous mandibular implant, but all stress values were lower than the yield strength of Ti-6Al-4V (800 MPa). The strain value of the bone surrounding the mandibular implant was affected not only by the shape and size of the pores but also by the chewing mode. According to Frost’s mechanostat theory of bone, higher bone strain under the porous implants might help maintain or improve bone quality and bone strength. The findings of this study serve as a biomechanical reference for the design of 3D-printed titanium mandibular implants and require confirmation through clinical investigations.

Additive Manufacturing of Bioceramic Implants for Restoration Bone Engineering: Technologies, Advances, and Future Perspectives

“…The results showed that the pore size of the implant did affect the initial stage of bone regeneration and that a larger pore size (1.2 mm) was indeed more favorable for bone regeneration (compared to pore sizes of 0.8 and 1.0 mm). Fuh et al 133 used finite element analysis (FEA) to investigate the mechanical behavior of mandibular implants and found that implants with holes exhibited higher strains, which could be attributed to the presence of porosity makes the stress distribution uniform and preventing stress concentration and stresses compared to those without holes and that the strain values around the mandible were influenced by the shape and size of the holes.…”

Computational Models and Their Applications in Biomechanical Analysis of Mandibular Reconstruction Surgery

“…Nevertheless, bone is a highly complex structure with different types of tissue (e.g., cortical or cancellous) and specific characteristics such as viscoelasticity and anisotropy [22,97], and simple modeling assumptions may not fully capture the intricate complexity of bone [95]. To account for this complexity, some studies [21] 2006 -✓ ---Tie et al [29] 2006 ✓ ----Schuller-Götzburg et al [30] 2009 ✓ ✓ --HA Wu et al (a) [31] 2012 ✓ ✓ ---Wong et al [23] 2012 --✓ --Jedrusik-Pawłowska et al [32] 2013 [33] 2013 -✓ --CI & PF Chang et al [34] 2013 [36] 2014 -✓ --CI & PF Bujtár et al [37] 2014 -✓ ---Narra et al [38] 2014 -✓ -CoT -Pinheiro and Alves [39] 2015 --✓ --Al-Ahmari et al [40] 2015 -✓ ---Jahadakbar et al [41] 2016 ✓ ✓ -CoT -Mehle et al [42] 2016 -✓ ---Park et al (a) [43] 2016 ✓ ✓ ---Dahake et al [44] 2017 --✓ --Nasr et al [45] 2017 -✓ ---Moiduddin et al (a) [46] 2017 [47] 2017 ✓ ✓ -FT -Luo et al [48] 2017 -✓ --RA Sanal et al [49] 2017 -✓ ---Seebach et al [24] 2017 ✓ ✓ ---Gutwald et al [50] 2017 -✓ -FT -Yoda et al [18] 2018 [52] 2018 ✓ ✓ ---Hoefert and Taier [53] 2018 -✓ ---Gao et al [ [64] 2021 ✓ ✓ ✓ --Koper et al [25] 2021 -✓ -CoT -Lang et al [22] 2021 ✓ ✓ -CoT & FT CA Kang et al [65] 2021 [74] 2022 --✓ --Shen et al [27] 2022 --✓ CoT -Jung et al [75] 2022 have adopted more sophisticated modeling techniques. Some of th...…”

“…Underloading resorption, equilibrium, apposition, and overloading resorption are the four phases of bone remodeling, [31] 2012 -✓ -----Ti Jedrusik-Pawłowska et al [32] 2013 [36] 2014 -✓ ----✓ Ti Bujtár et al [37] 2014 ------✓ Ti Narra et al [38] 2014 -✓ -----Ti6Al4V ELI Al-Ahmari et al [40] 2015 -✓ -----Ti6Al4V ELI Jahadakbar et al [41] 2016 [67] 2021 In conclusion, while using bony implants, especially fibular flaps, is regarded as the gold standard in larger reconstructions, there is some general dissatisfaction amongst patient populations in terms of functionality and aesthetics [62]. Therefore, alternative solutions such as prosthetic implants have been proposed [27,74]. Furthermore, autogenous grafts impact the patient even more since there are two points of surgical intervention.…”

“…Although the stemmed prosthesis body performed within comparable stress ranges to the native mandible, they seem to be limited by the insertion into the medullary space. More recent papers take the design of winged prostheses a step further by optimizing other parameters such as material, length and porosity [27,55,61]. Considering the higher number of papers reviewing winged prostheses in comparison to stemmed, it seems as though this method has become more standard.…”

In Silico Investigation of Mandibular Reconstruction: Tissue Differentiation Dynamics with Particulate-Cancellous Bone Marrow Grafts under Varied Bite Forces and Implant Elastic Moduli

“…Over the past few decades, several studies have focused on implants' material (Kinoshita et al, 1997;Lee et al, 2020;Matsuo et al, 2012;Xiao et al, 2020) and geometry (Liu et al, 2022;Peng et al, 2021;Shen et al, 2022;van Kootwijk et al, 2022) to improve their performance. However, mechanical loading history also plays an important role in the bone healing process (Carter, 1987;Salisbury Palomares et al, 2009), while most research on implants currently evaluates it at a particular time point.…”