Effect of variations in mini-screw diameter, length, tapering, and thread depth on stress-strain distribution and displacement in alveolar bone: A three-dimensional finite element analysis.

Aim: The aim of this study was to examine the effects of materials used and the depth of extension into the pulp chamber on stress distribution in mandibular molar endodontically treated teeth with endocrown restoration using three-dimensional (3D) finite element analysis (FEA). Methodology: Three-dimensional finite element analysis models were obtained at two different pulp chamber extension depths by taking a tomography of a root canal-treated mandibular molar tooth extracted for periodontal reasons: 2.5 mm (Model A) and 3.5 mm (Model B). Models were divided into the following three groups according to material type used: Vita Enamic (VE), Lava Ultimate (LU), and IPS e.max CAD (EMX). The aforementioned model groups were further divided into the following two subgroups according to the types of cement used: NX3 and MaxCem Elite Chroma (MX). Maximum principal stress (MPa) values under 600 N vertical load were investigated to evaluate the effect of restoration design, material type, and cements used on stress distribution. Results: The maximum stress on the restoration was observed in the EMX material type (13.000 MPa) in the MX cement group in Model A, while the lowest was observed in the LU material (5.932 MPa) in the NX3 cement group in Model A. The areas of highest stress for both Models A and B were observed in the restoration areas corresponding to the enamel margins. Conclusion: Materials with a higher elastic modulus show a higher stress area on the restoration surface, while the stress values they transmit are lower. Materials with the elastic modulus close to dentin have more homogeneous stress distributions within the restoration. How to cite this article: Güntekin N, Mohammadi R, Tunçdemir MT. The effect of the material used and the pulp chamber extension depth on stress distribution of endocrowns: A three-dimensional finite element analysis. Int Dent Res 2022;12(Suppl.1):1-9. https://doi.org/10.5577/intdentres.436 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Success/failure of dental implants depends on stress transfer and distribution at the bone-implant interface. This study aimed to assess the stress distribution pattern in all-on-four maxillary restorations supported by porous tantalum and solid titanium implants using three-dimensional (3D) finite element analysis (FEA). In this FEA, a geometric model of an edentulous maxilla, Zimmer screw-vent tantalum and solid titanium implants were modelled. Four models with the all-on-four concept were designed. The fifth model had 6 vertical implants (all-on-six). Two different implant types (porous tantalum and solid titanium) were modelled to yield a total of 10 models, and subjected to 200 N bilateral vertical load. Pattern of stress distribution and maximum von Mises stress values in cancellous and cortical bones around implants were analysed. In tantalum models, the effect of increasing the distal tilting of posterior implants was comparable to the effect of increasing the number of implants to 6 on von Mises stress values in cortical bone. However, in cancellous bone, the effect of increasing the tilting of posterior implants on stress was slightly greater than the effect of increasing the number of implants to 6. In solid titanium models, the effect of both of the abovementioned parameters was comparable on stress in cancellous bone; but in cortical bone, the effect of increasing the implant number was slightly greater on stress reduction. Despite similar pattern of stress distribution in bone around implants, higher maximum von Mises stress values around tantalum implants indicate higher stress transfer capacity of this type of implant to the adjacent bone, compared with solid titanium implants.

Statement of Problem: Treatment with dental implants owes much of its success to the development and maintenance of an osseointegrated bone-implant interface. The development of this interface is influenced by various factors, of which implant thread design plays a dominant role. Purpose: The purpose of this study is to analyze the effect of thread depth in four different thread designs on the stress distribution at the implant-bone interface using three-dimensional finite element analysis. Materials and Methods: Four implant models with different thread shapes, namely V thread, square thread, buttress thread, and reverse buttress thread with an uniform thread depth of 0.4 mm were designed. These models were then placed in the mandibular first molar region. Force of 100 N was applied axially and at 45°angle to the implant. Von Mises stress was measured at the implant – Bone interface area and compared for the different designs. Results: The color plots obtained were studied and the maximum Von Mises stress was noted and tabulated for each condition. Stress distribution in the finite element models comes in the numerical values and in color coding. Maximum values of Von Mises stress are denoted by red color and minimum value by blue color. In between, the values are represented by bluish green, green, greenish yellow, and yellowish red in the ascending order of stress distribution. Conclusion: Thread design plays an important role in stress distribution in implant and bone. Varying Von Mises stress is seen at the cortical bone-implant and cancellous bone-implant interface. Clinical Implication: Successful osseointegration is necessary for implant success and thread design plays a very important role in osseointegration. Therefore, the selection of implants with proper thread design contributes greatly to the success of an implant-retained prosthesis.

ObjectivesThis study aimed to optimize the thread depth and pitch of a recently designed dental implant to provide uniform stress distribution by means of a response surface optimization method available in finite element (FE) software. The sensitivity of simulation to different mechanical parameters was also evaluated.Materials and MethodsA three-dimensional model of a tapered dental implant with micro-threads in the upper area and V-shaped threads in the rest of the body was modeled and analyzed using finite element analysis (FEA). An axial load of 100 N was applied to the top of the implants. The model was optimized for thread depth and pitch to determine the optimal stress distribution. In this analysis, micro-threads had 0.25 to 0.3 mm depth and 0.27 to 0.33 mm pitch, and V-shaped threads had 0.405 to 0.495 mm depth and 0.66 to 0.8 mm pitch.ResultsThe optimized depth and pitch were 0.307 and 0.286 mm for micro-threads and 0.405 and 0.808 mm for V-shaped threads, respectively. In this design, the most effective parameters on stress distribution were the depth and pitch of the micro-threads based on sensitivity analysis results.ConclusionBased on the results of this study, the optimal implant design has micro-threads with 0.307 and 0.286 mm depth and pitch, respectively, in the upper area and V-shaped threads with 0.405 and 0.808 mm depth and pitch in the rest of the body. These results indicate that micro-thread parameters have a greater effect on stress and strain values.

Introduction: Radicular rehabilitation in cases of flared canals presents a challenge and is influenced by the type of post and the ferrule design. Use of anatomic posts has been advocated in such cases to allow for homogenous stress distribution. Hence, the aim of the present study was to evaluate and compare the effect of ferrule height, configuration, and post and core approaches on stress distribution of endodontically treated teeth with flared root canal by three-dimensional (3D) finite element analysis. Materials and Methods: Thirteen 3D models of single rooted maxillary second premolar were made using the solid works 2014 software. These were divided into four Groups I, II, III, and IV restored with no post, glass fiber, anatomic, and cast post and core, respectively. Group II, III, and IV were further subdivided into four subgroups a – no ferrule, b – 3 mm circumferential, c – incomplete ferrule of 2.5 mm on buccal and 1.5 mm on palatal side, and d – incomplete ferrule of 1.5 mm on buccal and 2.5 mm on palatal side. Load of 200 N at an angle of 45° was applied to buccal and palatal cusps. ANSYS/ABACUS standard solver with Microsoft Windows 10 Professional was used to analyze model data and perform stress analysis around various elements when subjected to occlusal loading in three dimensions. The maximum von Mises stresses were calculated within post, core, cervical, and radicular dentin and distribution at dentin and cement interface and cement and post interface. Results: The minimum stresses were seen in model restored with 3 mm circumferential ferrule with anatomic post and minimal stress was observed with no ferrule and rehabilitation with cast post. The presence of ferrule reduces the stress distribution in all the models. Incomplete ferrule design is associated with high stresses than partial ferrule. Conclusion: Ferrule allows for a uniform stress distribution and also reduces the stresses at the cervical region of the tooth. Palatal ferrule is more important to provide a fracture resistance to tooth as compared to buccal ferrule.

Determining the distal cantilever length in All-on-Four (All-on-4) implant-supported prostheses is a major factor in the long-term success of these prostheses. The difference in mechanical properties of materials used in the fabrication of these prostheses, such as polyether ether ketone (PEEK), may have an impact on the determination of the cantilever length that best distributes stress. To study the distribution of stress in All-on-4 mandibular prostheses in the bone, implants, and framework according to difference cantilever length in PEEKprosthetic framework using three-dimensional finite element analysis. A three-dimensional (3D) model of an edentulous mandible was constructed, implants and abutments models were designed by the All-on-4 concept, and two frameworks were constructed from PEEK with different cantilever lengths of 10 and 15 mm. Two study groups were created. Occlusal oblique forces of 600N were applied from the right side at a 45-degree angle, and finite element analysis was performed to obtain the stress distribution in the bone, implants, and framework. At cantilever length of 10 mm, in the PEEK model, this study found an increase in stress compared to PEEK model at cantilever length of 15 mm in the cortical bone and implants and framework, but PEEK models showed a similar distribution of stress in the spongy bone. Decreasing the cantilever length in the PEEK model will increase the stress.PEEK models showed deformation of the structure material.

The load transfer between the implant-bone interface depends on various factors, including loading type; material properties of the implant and prosthesis; and implant geometry, length, diameter, and shape. The purpose of this study was to evaluate stress distribution in single tilted bone-level implants with different connections and peripheral bone under vertical and oblique loads using three-dimensional (3D) finite element analysis (FEA).METHOS.3D models of four different implant systems and their abutments were created from the data (computer-aided design) of original implants and abutments scanned with an optical scanner. The implants were placed in the bone block at degrees of 0°, 15°, and 30°. Then, a 3D model of the metal-ceramic crown was created and a 100-N total load was applied vertically and obliquely. Stress analyses showed variable results depending on the connection design and tilting angle; however, the tube in tube (TIT) connection type exhibited lower stress values in most loading and tilting simulations. Increase in tilting angle showed variable results in each connection design. The TIT connection design was found to be more successful in terms of stress distributions in the implant components and the peripheral bone.

The aim of this study was to evaluate the effect of implant inclination and cantilever length on the stress distribution in mandibular cortical bone, implant, abutment, prosthetic framework, and prosthetic screw via three-dimensional (3D) finite element analysis (FEA). Four different finite element models (0-0, 17-17, 30-30, 45-30) were designed according to the tilting angle (0, 17, 30, and 45 degrees) of the posterior implant and angle of multiunit abutments (0, 17, and 30 degrees). Screw-retained fixed prostheses with different cantilever lengths in accordance with implant inclination were modeled. A foodstuff was used for the 100-N load application. Maximum principal (Pmax) and minimum principal (Pmin) stresses were calculated for cortical bone, and von Mises stress values were calculated for the implant, abutment, metal framework, and prosthetic screw. The highest stress values were observed in the anterior implant, surrounding bone, and prosthetic components of the 0-0 configuration. Pmin stress values in bone were gradually decreased with the increasing inclination of both anterior and posterior implants. Peak Pmax stress values were detected in the 0-0 group. For the cortical bone around the posterior implant, the 30-30 group showed the lowest Pmax value. The highest von Mises stress on implants was found at the posterior implant of the 30-30 group. The stress values on abutments gradually decreased with the increase of the angulation of the posterior implants. For prosthetic screws, the 30-30 and 45-30 groups exhibited lower stress values, and for the metal framework, the 30-30 group exhibited lower stress values. Biomechanical comparison via 3D FEA revealed that decreasing the cantilever length by tilting the posterior implants resulted in a reduction in stress values in the peri-implant bone, abutment, prosthetic screw, and metal framework. The groups with 30- and 45-degree tilted posterior implants and shorter cantilever lengths showed better stress distributions in comparison to the straight and 17-degree tilted groups.

Background. This study aimed to evaluate the effect of an increase in fixture thread face angle on the amount and distribution of stresses in the surrounding bone of implants with four different thread shapes by three-dimensional finite element analysis. Methods. Eight different fixture designs, with v-shaped, buttress, reverse buttress, and trapezoid threads, and two face angles of 20 and 35 degrees, were modeled using a software program. Each model was affected by two static forces with different values and angles (200-N axial 0° force and 100-N 45° oblique force) to compare the distribution of stress in different fixture designs. Results. The maximum von Mises stress was detected in v-shaped threads. An increase in the angle of the threads to 35° significantly decreased maximum von Mises stress in cortical bone in v-shaped and reverse buttress threads; however, the von Mises stress in the trapezoid and buttress threads increased with an increase in the thread angle. Conclusion. Under the limitations of this study, although the shape of the thread and thread surface angle does not have a definite role in stress distribution in the bone surrounding the implant, they are effective in the amount and type of stress induced in the bone supporting the implant.

Three-dimensional finite element analysis in cylindrical coordinates for nonlinear solid mechanics problems

Background Splinting of teeth is performed for effective distribution of loads in mobile teeth and to lower the stress applied to compromised teeth. Biomechanics cannot adequately explain load distribution around natural teeth. This study aimed to compare the distribution pattern and magnitude of stress and strain around splinted and non-splinted teeth with compromised periodontium using three-dimensional (3D) finite element analysis (FEA). Methods Six mandibular anterior teeth were scanned and data were registered in CATIA® and then SolidWorks® software programs. The jawbone was also designed. In the second model, the teeth were splinted with fiber-reinforced composite (FRC). The models were then transferred to ANSYS® software program and after meshing and fixing, 100- and 200-N loads were applied at zero and 30° angles. The magnitude and distribution of stress and strain in the periodontal ligament (PDL) and the surrounding cortical bone were determined. Results A significant reduction in stress was noted in cortical bone around central and lateral incisors while an increase in stress was noted around the canine tooth after splinting. All these changes were more significant under 100-N load compared to 200-N load and greater differences were noted in response to the application of oblique loads compared to vertical loads. Conclusion Splinting decreased the magnitude of stress and strain in teeth close to the center of splint and increased the stress and strain in teeth far from the center of splint. Adequate bone support of canine teeth must be ensured prior to selection of splinting as the treatment plan for the anterior mandible since it increases the longevity of all the teeth.

AimThe aim of this study was to evaluate the effect of impact stress on a primary central incisor with and without a strip crown and mouthguard using finite element analysis (FEA).MethodologyFour three-dimensional (3D) FEA models of a normal primary central incisor and strip crown with and without a 2 mm ethylene vinyl acetate (EVA) mouthguard were obtained from a cone-beam computed tomography (CBCT) scan of a 3-year-old child. Boundary conditions were defined. Impact analysis was carried out in Ansys Inc. software.ResultsResults were obtained through von Mises analysis. Such analyses involve the process of color mapping to determine the distribution of stress. Normal primary maxillary central incisors without mouthguards and primary central incisors with strip crowns reported higher stresses compared to models with mouthguards.ConclusionA 2 mm custom-fitted EVA mouthguard was effective in mitigating impact stress in the dentition of 3–5-year-old children. Therefore, the use of mouthguards should be encouraged in clinical practice, even for small children.How to cite this articleMridul M, Chaudhary K, Khanduri N, et al. Comparison of Effectiveness of 2 mm Thick Mouthguard on Primary Central Incisor with and without Strip Crown Restoration: A Three-dimensional Finite Element Analysis. Int J Clin Pediatr Dent 2025;18(4):363–367.

Objectives:This study sought to assess the effects of length and inclination of implants on stress distribution in an implant and terminal abutment teeth in an implant assisted-removable partial denture (RPD) using three-dimensional (3D) finite element analysis (FEA).Materials and Methods:In this in vitro study, a 3D finite element model of a partially dentate mandible with a distal extension RPD (DERPD) and dental implants was designed to analyze stress distribution in bone around terminal abutment teeth (first premolar) and implants with different lengths (7 and 10 mm) and angles (0°, 10° and 15°).Results:Stress in the periodontal ligament (PDL) of the first premolar teeth ranged between 0.133 MPa in 10mm implants with 15° angle and 0.248 MPa in 7mm implants with 0° angle. The minimum stress was noted in implants with 10mm length with 0° angle (19.33 MPa) while maximum stress (25.78 MPa) was found in implants with 10mm length and 15° angle. In implants with 7 mm length, with an increase in implant angle, the stress on implants gradually increased. In implants with 10 mm length, increasing the implant angle gradually increased the stress on implants.Conclusion:Not only the length of implant but also the angle of implantation are important to minimize stress on implants. The results showed that vertical implant placement results in lower stress on implants and by increasing the angle, distribution of stress gradually increases.

Occlusal trauma caused by improper bite forces owing to the lack of periodontal membrane may lead to bone resorption, which is still a problem for the success of dental implant. In our study, to avoid occlusal trauma, we put forward a hypothesis that a microelectromechanical system (MEMS) pressure sensor is settled on an implant abutment to track stress on the abutment and predict the stress on alveolar bone for controlling bite forces in real time. Loading forces of different magnitudes (0 N–100 N) and angles (0–90°) were applied to the crown of the dental implant of the left central incisor in a maxillary model. The stress distribution on the abutment and alveolar bone were analyzed using a three-dimensional finite element analysis (3D FEA). Then, the quantitative relation between them was derived using Origin 2017 software. The results show that the relation between the loading forces and the stresses on the alveolar bone and abutment could be described as 3D surface equations associated with the sine function. The appropriate range of stress on the implant abutment is 1.5 MPa–8.66 MPa, and the acceptable loading force range on the dental implant of the left maxillary central incisor is approximately 6 N–86 N. These results could be used as a reference for the layout of MEMS pressure sensors to maintain alveolar bone dynamic remodeling balance.

The aim of this study was to elucidate the association between the bone structure at implant insertion sites and stress distribution around the mandibular canal by means of three-dimensional finite element (3D FE) analysis. Four FE models were created with slice data using micro-computed tomography (micro-CT), and 3D FE analysis was performed. Mechanical analysis showed that the load reached the mandibular canal via the trabecular structure in all FE models. High levels of stress were generated around the mandibular canal when the distance between the mandibular canal and the implant decreased. High stress levels were also observed when cortical bone thickness and bone volume/total volume (BV/TV) were low. Our findings suggest that load is transmitted to the mandibular canal regardless of differences in the thickness of cortical bone or cancellous bone structure, but excessive load may be generated in bone with thin cortical and coarse cancellous structures.