Stress Concentration In Bone Research Articles

Comparison of Stress Distribution in Fixed Partial Prosthesis Restored with Different Combination of Support: A Finite Element Study.

This study was conducted to evaluate the distribution of stress in the bone around the natural tooth, endodontically treated tooth having post and core, and implant as an abutment in different combinations in fixed partial prosthesis using two-dimensional finite element analysis (FEA). Six models were simulated using ANSYS Modeller19. All six models were divided into 12 zones and 4 lines, and stress values were calculated and compared. The study combinations were - tooth supported fixed partial prosthesis, fixed partial prosthesis having the combination of tooth and post- and core-treated tooth, fixed partial prosthesis with the combination of tooth and implant, fixed partial prosthesis having the combination of implant and post- and core-treated tooth, fixed partial prosthesis with the combination of post- and core-treated tooth on both sides, and fixed partial prosthesis having the combination of implant on both sides. On comparing the stress values, the maximum stress value was observed in fixed partial prosthesis having the combination of implant on both sides (306.2434 MPa) followed by Model 4 (223.1255 MPa), Model 3 (154.3952 MPa), Model 5 (136.9041 MPa), Model 2 (116.2034 MPa), and least stress seen in Model 1 (99.6209 MPa), and minimum in tooth supported fixed partial prosthesis (99.6209 MPa). This study concluded that stress concentration in bone was maximum when the implant was used as an abutment in fixed partial prosthesis. The least stress was seen in bone around the natural tooth due to the dampening effect of the periodontal ligament. Further, the modulus of elasticity of a post acts as a vital parameter in the distribution of stress in post- and core-treated tooth. The stress concentration in the bone around the abutments affects the longevity of the prosthesis, hence, the clinically appropriate combination of the abutments should be considered for a fixed partial prosthesis.

A three-dimensional finite element analysis of permanent maxillary central incisors in different stages of root development and trauma settings

Background and objectivesDifferences in dental maturation may affect the prognosis and clinical management of traumatized teeth. However, evaluation of the outcomes of dental trauma to the tooth and support structures in an in vivo model involves major methodological and ethical implications. Thus, the aim of the present study was to perform a three-dimensional finite element analysis of permanent maxillary central incisors in different stages of root development under different trauma settings. MethodsThe study factors included two trauma conditions (B, buccal; I, incisal) on upper permanent central incisors showing three different stages of root development (CR, complete rhizogenesis; IRA; incomplete rhizogenesis in the apical third of the root; and IRM, incomplete rhizogenesis in the middle third of the root) to yield six models. The complete rhizogenesis model was obtained with a cone-beam computed tomography examination of an extracted tooth. The two incomplete rhizogenesis models were modeled on the basis of similar examinations of patients. Trauma was simulated by applying a 300 N static surface to surface load on the incisal edge or perpendicular to the buccal surface of the tooth. The displacement and equivalent von Mises (σvM) stress values were obtained for alveolar bone, periodontal ligament, apical papilla, and dentin for the quantitative analysis. A σvM color-coded scale was used for qualitative analysis. ResultsThe force direction had a greater influence on the stress than the root-formation stage. Buccal forces resulted in higher stress concentration in the bone and periodontal ligament, especially in B-CR. Lower stress was found on the periodontal ligament as the root formation progressed (decrease of 8% from B-IRA to B-CR and 11% from B-IRM to B-CR). The incomplete rhizogenesis models showed higher σvM stress peak values in dentin in comparison with complete rhizogenesis (increase of 52% from B-CR to B-IRA and 56% from B-CR to B-IRM). ConclusionsBuccal forces yielded greater stress values regardless of the stage of rhizogenesis. Teeth with fully formed roots showed a higher stress concentration in the alveolar bone and periodontal ligament in comparison with immature teeth, with the latter presenting high stresses in the tooth crown.

Stress distribution around different abutments on titanium and CFR-PEEK implant with different prosthetic crowns under parafunctional loading: A 3D FEA study

Aim & objectivesClinical trials had concluded a significant relationship between implant failure and bruxism. A three-dimensional (3D) finite element analysis (FEA) was done to evaluate the stress distribution in straight and angled abutments around titanium and carbon fiber-reinforced polyetheretherketone (CFR-PEEK) implant with 2 different prosthetic crowns under parafunctional loading. Materials and methodTwelve 3D models of bone block were created representing the maxillary right premolar area with osseointegrated implants. The models were divided in two group; CFR-PEEK implant (n ​= ​6) and group titanium implant (n ​= ​6).Each group was subdivided based on implants with three different abutments (straight, 15°, 25° angled abutments) and having two different prosthetic crowns: porcelain fused to metal (PFM) and polyetheretherketone (PEEK). A vertical load of 1000 ​N was applied to the central fossa and an oblique load of 500 ​N (30°) was applied to the buccal incline of the palatal cusp. The von Mises stresses and principal stresses were analyzed using ANSYS software. ResultsCFR-PEEK and titanium implants produced similar stress in bone under vertical and oblique loading. Straight abutment showed better results than 15° and 25° angled abutments in all the groups. PEEK crown produced lesser stress than PFM crown under vertical and oblique loading. ConclusionThe study concluded that straight abutment along with PEEK crown could be given in patients with bruxism to reduce the stress concentration in bone, thus preventing possible implant failure. Titanium and CFR-PEEK implants with straight abutments if given, then it should be provided with an occlusal splint.

Effects of implant neck design on primary stability and overload in a type IV mandibular bone.

This study investigates the effect of implant neck design on primary stability and overload using 3D finite element analysis. Four commercial dental implants and mandibular segments are created. Various parameters including the osseointegration condition (non-osseointegration and full osseointegration), force direction (vertical and horizontal), and cortical bone thickness (Tc = 0.3, 0.5, and 1 mm) are considered. The vertical and horizontal forces, 500 N and 250 N, are statically applied at the top of the platform, respectively. Micromotion and von Mises stress are employed to evaluate the risk of osseointegration and bone fatigue before osseointegration condition. After osseointegration, the principal stress is used to analyze the bone overload. Maximal von Mises stress and micromotion of the peri-implant bone decreased as cortical bone thickness increased. Horizontal force induces stress concentration in the bone around the implant neck easier than that of vertical force, and it may result in crestal bone loss. Thinner cortical bone should avoid dental implantation because it causes a noteworthy larger micromotion and stress concentration in cortical bone in particular Tc less than 0.3 mm.

Analysis of stress concentration in bone–implant interface using different shapes of the implant: Porous Ti and ultra-fine grained Ti

Background/aimsThe effect of materials that are used to make an implant is an essential factor and should be considered to predict the damage of the bone and implant. Different materials have different Young's modulus and they produce different stress concentration in bone. MethodsThree-dimensional finite element models of different implants were analyzed using Ansys workbench 12. In this study we compared porous titanium and ultra-fine grained titanium covered by Hydroxyapatite. We used 180 μm thickness of Hydroxyapatite for the ultra-fine grained titanium according to the former studies. Different shapes of the implant have been modeled and all of them showed that the ultra-fine grained titanium has lower stress concentration near bone. Results and conclusionResults show that ultra-fine grained titanium has better distribution of the interface stress, so it shows better compatibility to the bone. The effect of Hydroxyapatite as an important factor is considered. Non-linear analysis was used to evaluate the results that show that models I and III are the best models when ultra-fine grained-Ti is used.

Finite element analysis of an ultra-fine grained Titanium dental implant covered by different thicknesses of hydroxyapatite layer

Background/AimsCoating dental implants with hydroxyapatite (HA) layer has been widely used in last decades due to its numerous advantages. Stress concentration in the implant is an essential factor as it can cause the fracture of the implant. MethodsWe compared the effect of different thicknesses of hydroxyapatite layer on stress concentration in a nano-Titanium dental implant with finite element method (FEM) software under 200 N axial chewing load applied on the top of the implant in order to see which one has the lowest stress concentration and is best for dental applications. Results and conclusionThe results show that the best thickness of the hydroxyapatite layer is 180 μm which minimizes the stress concentration in bone and maximizes the life of the implant.

Finite element modelling of implant designs and cortical bone thickness on stress distribution in maxillary type IV bone

The aims of this study were to examine the effect of implant neck design and cortical bone thickness using 3D finite element analysis and to analyse the stability of clinical evidence based on micromotion and principal stress. Four commercial dental implants for a type IV bone and maxillary segments were created. Various parameters were considered, including the osseointegration condition, loading direction and cortical bone thickness. Micromotion and principal stresses were used to evaluate the failure of osseointegration and bone overloading, respectively. It was found that the maximum stress of the peri-implant bone decreased as cortical bone thickness increased. The micromotion level in full osseointegration is less than that in non-osseointegration and it also decreases as cortical bone thickness increases. The cortical bone thickness should be measured before surgery to help select a proper implant. In the early stage of implantation, the horizontal loading component induces stress concentration in bone around the implant neck more easily than does the vertical loading component, and this may result in crestal bone loss.

Measurement of partition of stress between mineral and collagen phases in bone using X-ray diffraction techniques

The aim of this study was to present clear evidence of a stress concentration in bone as a two-phase composite of a collagen matrix reinforced by hydroxyapatite (HAP) mineral particles. X-ray diffractometry was performed on cortical bone from a bovine femur in order to measure strain in HAP along the c-axis as a response to a macroscopically applied force. From the obtained strain of HAP, the stress applied to HAP particles was determined by using Young's modulus value of HAP in the literature. Dividing the stress of HAP by that macroscopically applied to a bone specimen, the stress concentration coefficient, χ H, was estimated. Using the Hirsch equation with the estimated χ H value, mineral content of bone was estimated, which accords with the mineral content values of bone in the literature.