Evaluation of stress and strain on mandible caused using “All-on-Four” system from PEEK in hybrid prosthesis: finite-element analysis

Abstract

Hybrid prostheses have recently been used as suitable treatment alternatives for edentulous individuals to restore the mastication mechanism. These prostheses utilize “All on four” concept, in which four implants are inserted into the jaw bone, and supported by a bar. Titanium is usually used in the fabrication of “All on four” parts due to its good mechanical properties. However, it has many drawbacks including esthetic impairment, casting issues, hypersensitivity reactions, stress shielding, and incompatibility with imaging techniques. These drawbacks have prompted researchers to find alternative materials (e.g., polymers). Recently, the new polymeric material PEEK has a major role in dentistry, due to its biocompatibility, shock-absorbing ability, and good mechanical properties. This work used the finite-element method to conduct stress–strain analysis on mandible rehabilitated with a hybrid prosthesis, using PEEK in the fabrication of “All on four” parts instead of titanium, using different densities of spongy bone. As the density of spongy bone is expected to influence the choice of “All on four” fabrication material. A 300 N vertical force was applied unilaterally, bilaterally, and anteriorly to stimulate the different mastication mechanisms. The results illustrated that PEEK material reduced the stresses and strains on bone tissues and increased the mucosal stress, compared to titanium. Consequently, this material was recommended to be used in the fabrication of “All on four” parts, especially in the low-density model. However, further research on PEEK implants and abutments is required in near future.

Investigating the Ability of the Tooth and Surrounding Support Tissues to Absorb and Dissipate Orthodontic Loads during Periodontal Breakdown—Finite Elements Analysis

“…Merdji et al [44] (lower third molar, intact periodontium, single model, sample size of one, Von Mises criteria, intrusion: 10 N, tipping/translation: 3 N, bone: 142,305 elements, global element size: 0.25-1 mm), reported similar qualitative results (cervical third alveolar bone socket stress), but with an extension on both vestibular and lingual sides (due to the three rooted anatomical reconstructions that are closer to bone-implant models [19][20][21][22][23][24][25][26][27] than tooth models). By following anatomical correctness, we addressed this issue in the herein models.…”

“…The acknowledged dental components' physical properties are: cortical bone-16.7 GPa of compressive modulus and 157 MPa of compressive strength; trabecular/cancellous bone-0.155 GPa of compressive modulus and 6 MPa of compressive strength [19][20][21][22][23][24][25][26][27]; enamel-62.2 MPa of compressive stress [1], 11.5-42.1 MPa of maximum tensile strength [11], and 53.9-104 MPa of maximum shear stress [13]; dentine-29-73.1 MPa of maximum shear stress; enamel-dentine-53.9-104 MPa of maximum shear stress [13].…”

“…The bone-implant [19][20][21][22][23][24][25][26]44] and bone-tooth [29,43,44] FEA studies employed S1-S3 (brittle-like) and Von Mises (ductile-like) failure criterion but without any discussion about the above-mentioned issues. Most of the above FEA studies employed included boundary conditions isotropy, linear elasticity, and homogeneity, despite the anatomical tissues being none of these, without addressing their suitability, adequacy, and influence over the results accuracy issues.…”

Effects of Increasing the Orthodontic Forces over Cortical and Trabecular Bone during Periodontal Breakdown—A Finite Elements Analysis

“…The circulatory disturbances trigger the orthodontic movements and remodeling of support tissues with limited effects in the intact periodontium (i.e., if light orthodontic forces are applied) [17][18][19], but variable and with unpredictable effects in the reduced periodontium (i.e., even under small loads) [17,18]. Despite numerous FEA (Finite Elements Method) studies regarding the effect of loads over the bone (bone-tooth [1,15,16,[20][21][22] and bone-implant [3,7,9,[23][24][25][26][27][28]) in the intact periodontium, no studies regarding the biomechanical behavior of bone subjected to a periodontal-breakdown process were found (except our team's previous studies [2,10,[12][13][14]17,18]).…”

“…In dental fields there are numerous FEA studies [1,3,7,9,15,16,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], but without any correlation with the type of analyzed material or with a maximum physiological hydrostatic pressure (MHP) of 16 KP (that if exceeded triggers ischemic and resorptive internal microarchitectural changes). These studies [1,3,7,9,15,16,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]…”