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Çelik T, Taş ZC. Biomechanical Evaluation of a Newly Developed Functional-Grade Composite Material for Pedicle Screws. World Neurosurg 2024; 187:e525-e533. [PMID: 38677644 DOI: 10.1016/j.wneu.2024.04.120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 04/18/2024] [Indexed: 04/29/2024]
Abstract
OBJECTIVE Pedicle screw and rod systems are widely employed in spine surgeries and loosening due to insufficient mechanical stimulation on the bone is frequently encountered in pedicle screws. This mechanical stimulation problem also arises due to the high rigidity of the implant material. This study aimed to develop new pedicle screws with composite material to solve the pedicle screw loosening problem. METHODS The vertebrae and vertebral disk were modeled in three dimension using computerized tomography images obtained from a patient. A commercially available pedicle screw was modeled using Fusion software, and all models were assembled in accordance with the surgical procedure. Pedicle screw models were also divided radially and longitudinally to resemble functionally graded materials, which are composite materials. The load was applied to the top of the T12 vertebra and the screw-vertebral system was fixed to the bottom of the L1 vertebra. RESULTS The strain results on the vertebrae were examined according to the mechanostat theorem. According to the results, functionally graded material (FGM) pedicle screw decreased the strain on the vertebral bones, and the positive effects on the bone were determined when using the radially functionally graded screws. The maximum stress values were also examined to determine the strengths of all the models. CONCLUSION In conclusion, FGM pedicle screw decreased the strain on the bone which is an important parameter for the loosening failure according to the study. The other important conclusion is that FGM pedicle screw can be the solution to the loosening of the screw but not in all vertebrae.
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Affiliation(s)
- Talip Çelik
- Faculty of Technology, Biomedical Engineering Department, Kocaeli University, Kocaeli, Turkey.
| | - Zeliha Coşkun Taş
- Faculty of Technology, Biomedical Engineering Department, Kocaeli University, Kocaeli, Turkey
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2
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Smotrova E, Li S, Silberschmidt VV. Trabecula-level mechanoadaptation: Numerical analysis of morphological changes. Comput Biol Med 2024; 168:107720. [PMID: 38006828 DOI: 10.1016/j.compbiomed.2023.107720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 09/22/2023] [Accepted: 11/15/2023] [Indexed: 11/27/2023]
Abstract
BACKGROUND Bone is a living material that, unlike man-made ones, demonstrates continuous adaptation of its structure and mechanical properties to resist the imposed mechanical loading. Adaptation in trabecular bone is characterised by improvement of its stiffness in the loading direction and respective realignment of trabecular load-bearing architecture. Considerable experimental and simulation evidence of trabecular bone adaptation to its mechanical environment at the tissue- and organ-levels was obtained, while little attention was given to the trabecula-level of this process. This study aims to describe and classify load-driven morphological changes at the level of individual trabeculae and to propose their drivers. METHOD For this purpose, a well-established mechanoregulation-based numerical model of bone adaptation was implemented in a user-defined subroutine that changed the structural and mechanical properties of trabeculae based on the magnitude of a mechanical stimulus. This subroutine was used in conjunction with finite-element models of variously shaped structures representing trabeculae loaded in compression or shear. RESULTS In all analysed cases, trabeculae underwent morphological evolution under applied compressive or shear loading. Among twelve cases analysed, six main mechanisms of morphological evolution were established: reorientation, splitting, merging, full resorption, thinning, and thickening. Moreover, all simulated cases presented the ability to reduce the mean value of von Mises stress while increasing their ability to resist compressive/shear loading during adaptation. CONCLUSION This study evaluated morphological and mechanical changes in trabeculae of different shapes in response to compressive or shear loadings and compared them based on the analysis of von Mises stress distribution as well as profiles of normal and shear stresses in the trabeculae at different stages of their adaptation.
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Affiliation(s)
- Ekaterina Smotrova
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, UK; Laboratory of Mechanics of Biocompatible Materials and Devices, Perm National Research Polytechnic University, Komsomolsky Ave., 29, Perm, 614000, Russia.
| | - Simin Li
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, UK
| | - Vadim V Silberschmidt
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough, UK
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Hijazi KM, Dixon SJ, Armstrong JE, Rizkalla AS. Titanium Alloy Implants with Lattice Structures for Mandibular Reconstruction. MATERIALS (BASEL, SWITZERLAND) 2023; 17:140. [PMID: 38203994 PMCID: PMC10779528 DOI: 10.3390/ma17010140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 11/30/2023] [Accepted: 12/19/2023] [Indexed: 01/12/2024]
Abstract
In recent years, the field of mandibular reconstruction has made great strides in terms of hardware innovations and their clinical applications. There has been considerable interest in using computer-aided design, finite element modelling, and additive manufacturing techniques to build patient-specific surgical implants. Moreover, lattice implants can mimic mandibular bone's mechanical and structural properties. This article reviews current approaches for mandibular reconstruction, their applications, and their drawbacks. Then, we discuss the potential of mandibular devices with lattice structures, their development and applications, and the challenges for their use in clinical settings.
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Affiliation(s)
- Khaled M. Hijazi
- School of Biomedical Engineering, Faculty of Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada
- Bone and Joint Institute, The University of Western Ontario, London, ON N6G 2V4, Canada
| | - S. Jeffrey Dixon
- Bone and Joint Institute, The University of Western Ontario, London, ON N6G 2V4, Canada
- Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
| | - Jerrold E. Armstrong
- Division of Oral and Maxillofacial Surgery, Department of Otolaryngology Head and Neck Surgery, Henry Ford Hospital, Detroit, MI 48202, USA
| | - Amin S. Rizkalla
- School of Biomedical Engineering, Faculty of Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada
- Bone and Joint Institute, The University of Western Ontario, London, ON N6G 2V4, Canada
- Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada
- Chemical and Biochemical Engineering, Faculty of Engineering, The University of Western Ontario, London, ON N6A 5B9, Canada
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De Stefano M, Lanza A, Sbordone L, Ruggiero A. Stress-strain and fatigue life numerical evaluation of two different dental implants considering isotropic and anisotropic human jaw. Proc Inst Mech Eng H 2023; 237:1190-1201. [PMID: 37667892 DOI: 10.1177/09544119231193879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Dental prostheses are currently a valid solution for replacing potential missing tooth or edentulism clinical condition. Nevertheless, the oral cavity is a dynamic and complex system: occlusal loads, external agents, or other unpleasant events can impact on implants functionality and stability causing a future revision surgery. One of the failure origins is certainly the dynamic loading originated from daily oral activities like eating, chewing, and so on. The aim of this paper was to evaluate, by a numerical analysis based on Finite Elements Method (FEM), and to discuss in a comparative way, firstly, the stress-strain of two different adopted dental implants and, subsequently, their fatigue life according to common standard of calculations. For this investigation, the jawbone was modeled accounting for either isotropic or anisotropic behavior. It was composed of cortical and cancellous regions, considering it completely osseointegrated with the implants. The impact of implants' fixture design, loading conditions, and their effect on the mandible bone was finally investigated, on the basis of the achieved numerical results. Lastly, the life cycle of the investigated implants was estimated according to the well-established theories of Goodman, Soderberg, and Gerber by exploiting the outcomes obtained by the numerical simulations, providing interesting conclusions useful in the dental practice.
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Affiliation(s)
- Marco De Stefano
- Department of Industrial Engineering, University of Salerno, Fisciano, Italy
| | - Antonio Lanza
- Department of Medicine, Surgery and Dentistry "Schola Medica Salernitana," University of Salerno, Baronissi, Italy
| | - Ludovico Sbordone
- Department of Medicine and Health Sciences, University of Molise, V Campobasso, Italy
| | - Alessandro Ruggiero
- Department of Industrial Engineering, University of Salerno, Fisciano, Italy
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Ouldyerou A, Mehboob H, Merdji A, Aminallah L, Mehboob A, Mukdadi OM. Biomechanical analysis of printable functionally graded material (FGM) dental implants for different bone densities. Comput Biol Med 2022; 150:106111. [PMID: 36195043 DOI: 10.1016/j.compbiomed.2022.106111] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 08/18/2022] [Accepted: 09/17/2022] [Indexed: 11/24/2022]
Abstract
The long-term success of a dental implant is related to the material and design of the implant, and bone density. Conventional implants cause stress-shielding due to a mismatch between the implant and bone stiffness. Functionally graded porous materials and designs are a great choice for the design of implants to control the local stiffness at a certain location to meet the biomechanical requirements. The purpose of this study is to analyze five designs of axial and radial functionally graded materials (FGM) implants besides the conventional implant and conical and cylindrical shapes that were simulated with five different bone densities. The results showed that strain in bone increased with a decrease in cancellous bone density. The shape of the implant did not play an important role in strain/stress distribution. Conventional implants showed optimal strain (1000-2240 με) in low-density (0.7-0.8 g/cm3) bone, however, FGM implants produced optimal strain (990-1280 με) in the high-density bone (0.9-1 g/cm3) as compared to conventional implants. The proposed designs of FGM implants have the potential to address the complications of conventional implants in high-density bone.
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Affiliation(s)
- Abdelhak Ouldyerou
- Department of Mechanical Engineering, Faculty of Science and Technology, University of Mascara, Mascara, Algeria.
| | - Hassan Mehboob
- Department of Engineering Management, College of Engineering, Prince Sultan University, Riyadh, 11586, Saudi Arabia.
| | - Ali Merdji
- Department of Mechanical Engineering, Faculty of Science and Technology, University of Mascara, Mascara, Algeria; Laboratory of Mechanics Physics of Materials (LMPM), Faculty of Technology, Djillali Liabes University, Sidi Bel-Abbes, 22000, Algeria.
| | - Laid Aminallah
- Department of Mechanical Engineering, Faculty of Science and Technology, University of Mascara, Mascara, Algeria.
| | - Ali Mehboob
- Department of Textile Engineering, School of Engineering and Technology, National Textile University, Faisalabad, Pakistan.
| | - Osama M Mukdadi
- Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV, 26506, USA.
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Mirulla AI, Pinelli S, Zaffagnini S, Nigrelli V, Ingrassia T, Paolo SD, Bragonzoni L. Numerical simulations on periprosthetic bone remodeling: a systematic review. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2021; 204:106072. [PMID: 33819822 DOI: 10.1016/j.cmpb.2021.106072] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND OBJECTIVE The aim of the present study was to review the literature concerning the analysis of periprosthetic bone remodeling through finite element (FE) simulation. METHODS A systematic review was conducted on 9 databases, taking into account a ten-year time period (from 2009 until 2020). The inclusion criteria were: articles published in English, publication date after 2009, full text articles, articles containing the keywords both in the abstract and in the title. The articles were classified through the following parameters: dimensionality of the simulation, modelling of the bone-prosthesis interface, output parameters, type of simulated prosthesis, bone remodeling algorithm. RESULTS Sixty-seven articles were included in the study. Femur and tooth were the most evaluated bone segment (respectively 41.8% and 29.9%). The 55.2% of the evaluated articles used a bonded bone-prosthesis interface, 73% used 3D simulations, 67.2% of the articles (45 articles) evaluate the bone remodeling by the bone density variation. At last, 59.7% of the articles employed algorithms based on a specific remodeling function. CONCLUSIONS Increasing interest in the bone remodeling FE analysis in different bone segments emerged from the review, and heterogeneous solutions were adopted. An optimal balance between computational cost and accuracy is needed to accurately simulate the bone remodeling phenomenon in the post-operative period.
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Affiliation(s)
- Agostino Igor Mirulla
- Department of Engineering, University of Palermo, Viale delle Scienze Ed.8, 90128 Palermo, Italy; Department of Biomedical and Neurmotor Sciences, University of Bologna, Via G. Pupilli 1, 40136 Bologna, Italy.
| | - Salvatore Pinelli
- Department of Information Engineering, University of Pisa, Pisa, Via G. Caruso 16, 56122 Pisa, Italy
| | - Stefano Zaffagnini
- Department of Biomedical and Neurmotor Sciences, University of Bologna, Via G. Pupilli 1, 40136 Bologna, Italy; 2nd Orthopaedic and Traumatologic Clinic, IRCCS Istituto Ortopedico Rizzoli, Via G. Pupilli 1, 40136 Bologna, Italy
| | - Vincenzo Nigrelli
- Department of Engineering, University of Palermo, Viale delle Scienze Ed.8, 90128 Palermo, Italy
| | - Tommaso Ingrassia
- Department of Engineering, University of Palermo, Viale delle Scienze Ed.8, 90128 Palermo, Italy
| | - Stefano Di Paolo
- Department of Biomedical and Neurmotor Sciences, University of Bologna, Via G. Pupilli 1, 40136 Bologna, Italy
| | - Laura Bragonzoni
- Department for Life Quality Studies, University of Bologna, Corso d'Augusto 237, 47921 Rimini, Italy
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Bartolomeu F, Dourado N, Pereira F, Alves N, Miranda G, Silva F. Additive manufactured porous biomaterials targeting orthopedic implants: A suitable combination of mechanical, physical and topological properties. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 107:110342. [DOI: 10.1016/j.msec.2019.110342] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 10/08/2019] [Accepted: 10/19/2019] [Indexed: 01/09/2023]
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Experimental Validation of an ITAP Numerical Model and the Effect of Implant Stem Stiffness on Bone Strain Energy. Ann Biomed Eng 2020; 48:1382-1395. [PMID: 31974868 PMCID: PMC7089889 DOI: 10.1007/s10439-020-02456-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 01/10/2020] [Indexed: 11/27/2022]
Abstract
The Intraosseous Transcutaneous Amputation Prosthesis (ITAP) offers transfemoral amputees an ambulatory method potentially reducing soft tissue complications seen with socket and stump devices. This study validated a finite element (in silico) model based on an ITAP design and investigated implant stem stiffness influence on periprosthetic femoral bone strain. Results showed good agreement in the validation of the in silico model against the in vitro results using uniaxial strain gauges and Digital Image Correlation (DIC). Using Strain Energy Density (SED) thresholds as the stimulus for adaptive bone remodelling, the validated model illustrated that: (a) bone apposition increased and resorption decreased with increasing implant stem flexibility in early stance; (b) bone apposition decreased (mean change = − 9.8%) and resorption increased (mean change = 20.3%) from distal to proximal in most stem stiffness models in early stance. By engineering the flow of force through the implant/bone (e.g. by changing material properties) these results demonstrate how periprosthetic bone remodelling, thus aseptic loosening, can be managed. This paper finds that future implant designs should be optimised for bone strain under a variety of relevant loading conditions using finite element models to maximise the chances of clinical success.
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Virtual Bone Augmentation in Atrophic Mandible to Assess Optimal Implant-Prosthetic Rehabilitation—A Finite Element Study. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10010401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The scope of our study was to analyze the impact of implant prosthetic rehabilitation, in bilateral terminal partial edentulism with mandibular bone atrophy, and potential benefits of mandibular bone augmentation through finite element analysis. A 3D mandible model was made using patient-derived cone-beam computed tomography (CBCT) images, presenting a bilateral terminal edentation and mandibular atrophy. A virtual simulation of bone augmentation was then made. Implant-supported restorations were modeled for each edentulous area. Forces corresponding to the pterygoid and the masseter muscles, as well as mastication conditions for each quadrant, were applied. The resorbed mandible presented high values of strain and stress. A considerable variation between strain values among the two implant sites in each quadrant was found. In the augmented model, values of strain and stress showed a uniformization in both quadrants. Virtually increasing bone mass in the resorbed areas of the mandible showed that enabling larger implants drastically reduces strain and stress values in the implant sites. Also, although ridge height difference between the two quadrants was kept even after bone augmentation, there is a uniformization of the strain values between the two implant sites in each of the augmented mandible quadrants.
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10
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Bartolomeu F, Fonseca J, Peixinho N, Alves N, Gasik M, Silva F, Miranda G. Predicting the output dimensions, porosity and elastic modulus of additive manufactured biomaterial structures targeting orthopedic implants. J Mech Behav Biomed Mater 2019; 99:104-117. [DOI: 10.1016/j.jmbbm.2019.07.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 07/18/2019] [Accepted: 07/20/2019] [Indexed: 12/17/2022]
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Bertolini MM, Del Bel Cury AA, Pizzoloto L, Acapa IRH, Shibli JA, Bordin D. Does traumatic occlusal forces lead to peri-implant bone loss? A systematic review. Braz Oral Res 2019; 33:e069. [PMID: 31576953 DOI: 10.1590/1807-3107bor-2019.vol33.0069] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 06/13/2019] [Indexed: 11/22/2022] Open
Abstract
Observational studies have indicated that crestal bone level changes at implants are typically associated with clinical signs of inflammation, but still mechanical overload has been described as possible factor leading to hard-tissue deficiencies at implant sites without mucosal inflammation. The aim of this paper was systematically review the literature regarding the possible effect of traumatic occlusal forces on the peri-implant bone levels. Literature search was conducted using PubMed, Scielo and Lilacs, including the following terms: oral OR dental AND implant$ AND (load OR overload OR excessive load OR force$ OR bruxism) AND (bone loss OR bone resorption OR implant failure$). Databases were searched for the past 10 years of publications, including: clinical human studies, either randomized or not, cohort studies, case control studies, case series and animal research. Exclusion criteria were review articles, guidelines and in vitro and in silico (finite element analysis) research, as well as retrospective studies. The PICO questions formulated was: "does traumatic occlusal forces lead to peri-implant bone loss?" The database searches as well as additional hand searching, resulted in 807 potentially relevant titles. After inclusion/exclusion criteria assessment 2 clinical and 4 animal studies were considered relevant to the topic. The included animal studies did not reveal an association between overload and peri-implant bone loss when lower overloads were applied, whereas in the presence of excessive overload it seemed to generate peri-implant bone loss, even in the absence of inflammation. The effect of traumatic occlusal forces in peri-implant bone loss is poorly reported and provides little evidence to support a cause-and-effect relationship in humans, considering the strength of a clinically relevant traumatic occlusal force.
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Affiliation(s)
| | - Altair Antoninha Del Bel Cury
- Universidade Estadual de Campinas - Unicamp, Piracicaba Dental School, Department of Prosthodontics and Periodontology, Piracicaba, SP, Brazil
| | - Lucas Pizzoloto
- Universidade de Guarulhos - UNG, Department of Restorative Dentistry, Guarulhos, SP, Brazil
| | | | - Jamil Awad Shibli
- Universidade de Guarulhos - UNG, Department of Periodontology and Oral Implantology, Guarulhos, SP, Brazil
| | - Dimorvan Bordin
- Universidade de Guarulhos - UNG, Department of Restorative Dentistry, Guarulhos, SP, Brazil
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Skedros JG, Su SC, Knight AN, Bloebaum RD, Bachus KN. Advancing the deer calcaneus model for bone adaptation studies: ex vivo strains obtained after transecting the tension members suggest an unrecognized important role for shear strains. J Anat 2018; 234:66-82. [PMID: 30411344 DOI: 10.1111/joa.12905] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/10/2018] [Indexed: 12/15/2022] Open
Abstract
Sheep and deer calcanei are finding increased use as models for studies of bone adaptation, including advancing understanding of how the strain (deformation) environment influences the ontogenetic emergence of biomechanically relevant structural and material variations in cortical and trabecular bone. These artiodactyl calcanei seem ideal for these analyses because they function like simply loaded short-cantilevered beams with net compression and tension strains on the dorsal and plantar cortices, respectively. However, this habitual strain distribution requires more rigorous validation because it has been shown by limited in vivo and ex vivo strain measurements obtained during controlled ambulation (typically walking and trotting). The conception that these calcanei are relatively simply and habitually loaded 'tension/compression bones' could be invalid if infrequent, though biologically relevant, loads substantially change the location of the neutral axis (NA) that separates 'compression' and 'tension' regions. The effect on calcaneus strains of the tension members (plantar ligament and flexor tendon) is also not well understood and measuring strains after transecting them could reveal that they significantly modulate the strain distribution. We tested the hypothesis that the NA location previously described during simulated on-axis loads of deer calcanei would exhibit limited variations even when load perturbations are unusual (e.g. off-axis loads) or extreme (e.g. after transection of the tension members). We also examined regional differences in the predominance of the three strain modes (tension, compression, and shear) in these various load conditions in dorsal, plantar, medial, and lateral cortices. In addition to considering principal strains (tension and compression) and maximum shear strains, we also considered material-axis (M-A) shear strains. M-A shear strains are those that are aligned along the long axis of the bone and are considered to have greater biomechanical relevance than maximum shear strains because failure theories of composite materials and bone are often based on stresses or strains in the principal material directions. We used the same load apparatus from our prior study of mule deer calcanei. Results showed that although the NA rotated up to 8° medially and 15° laterally during these off-axis loads, it did not shift dramatically until after transection of all tension members. When comparing results based on maximum shear strain data vs. M-A shear strain data, the dominant strain mode changed only in the plantar cortex - as expected (in accordance with our a priori view) it was tension when M-A shear strains were considered (shear : tension = 0.2) but changed to dominant shear when maximum shear strain data were considered (shear : tension = 1.3). This difference leads to different conclusions and speculations regarding which specific strain modes and magnitudes most strongly influence the emergence of the marked mineralization and histomorphological differences in the dorsal vs. plantar cortices. Consequently, our prior simplification of the deer calcaneus model as a simply loaded 'tension/compression bone' (i.e. plantar/dorsal) might be incorrect. In vivo and in finite element analyses are needed to determine whether describing it as a 'shear-tension/compression' bone is more accurate. Addressing this question will help to advance the artiodactyl calcaneus as an experimental model for bone adaptation studies.
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Affiliation(s)
- John G Skedros
- Department of Orthopedics, University of Utah, Salt Lake City, UT, USA.,Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Steven C Su
- Department of Orthopedics, University of Utah, Salt Lake City, UT, USA.,Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA.,Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Alex N Knight
- Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Roy D Bloebaum
- Rehabilitation Research and Development Service, VA Medical Center, Salt Lake City, UT, USA
| | - Kent N Bachus
- Department of Orthopedics, University of Utah, Salt Lake City, UT, USA.,Department of Veterans Affairs Medical Center, Salt Lake City, UT, USA
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13
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Rittel D, Dorogoy A, Shemtov-Yona K. Modeling the effect of osseointegration on dental implant pullout and torque removal tests. Clin Implant Dent Relat Res 2018; 20:683-691. [PMID: 30051951 DOI: 10.1111/cid.12645] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 05/01/2018] [Accepted: 05/06/2018] [Indexed: 12/31/2022]
Abstract
BACKGROUND Osseointegration of dental implants is a key factor for their success. It can be assessed either by destructive (eg, pullout or torque extraction), or nondestructive methods (eg, resonant frequency analysis). However, as of today there is a scarcity of models that can relate the outcome of destructive tests to the level of osseointegration. PURPOSE To study various percentages of bone to implant bonding (tie) using finite element simulations. While evolutions of the bone mechanical properties are not explicitly taken into account, emphasis is put on the 3-dimensional variable extent of the bone-implant bonding, its statistical distribution, and its influence on the measurable extraction and torque loads, seeking to obtain a quantitative relationship. MATERIALS AND METHODS We performed numerical simulations of randomly tied implants and calculated the evolution of the pullout force as well as that of the extraction torque. CONCLUSION Within simplifying assumptions for the osseointegration represented by a tie (as opposed to frictional) constraint, the results of this work indicate that the torque test is more discriminant than the extraction one, while both cannot really discriminate osseointegration levels below a relative variation of 20%.
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Affiliation(s)
- Daniel Rittel
- Technion, Faculty of Mechanical Engineering, 32000, Haifa, Israel
| | - Avraham Dorogoy
- Technion, Faculty of Mechanical Engineering, 32000, Haifa, Israel
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14
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Hingsammer L, Watzek G, Pommer B. The influence of crown-to-implant ratio on marginal bone levels around splinted short dental implants: A radiological and clincial short term analysis. Clin Implant Dent Relat Res 2017; 19:1090-1098. [PMID: 29024303 DOI: 10.1111/cid.12546] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 08/06/2017] [Accepted: 09/15/2017] [Indexed: 12/21/2022]
Abstract
BACKGROUND The amount of marginal bone resorption around dental implants is considered to have a significant impact on implant stability as well as implant survival rates. PURPOSE The aim of this prospective study was to investigate the influence of prosthetic as well as patient specific factors on marginal bone loss around short dental implants. MATERIALS AND METHODS Seventy-six implants, which supported splinted crowns were included for investigation. All implants were from the same type and had an intraosseous length of 6.5 mm and a diameter of 4.0 mm. Twenty implants were additionally splinted onto longer ones. Measurements of marginal bone loss were performed at a mean of 12.38 months after prosthetic loading and the mean follow-up for clinical evaluation was 20.52 months. RESULTS Overall two implant failures were recorded, revealing a survival rate of 97.3%. Marginal bone resorption around 72 short implants measured 0.71 mm (SD: 0.74 mm) and was found to have a strong correlation with calculated Crown-to-Implant ratio (r = .71; P < .001). Age, gender, insertion torque, implant surface area, location, position, bone quality, and insertion torque did not influence peri-implant bone loss after one year of loading. CONCLUSION Within the limitations of the study, it is suggested that Crown-to-Implant ratios should not exceed 1.7 to avoid increased early marginal bone loss.
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Affiliation(s)
- Lukas Hingsammer
- University Hsopital Zurich, Department of Oral and Maxillofacial Surgery, Frauenklinikstrasse 24, 8032 Zurich, Switzerland.,Oral Surgeon, Academy of Oral Implantology, Lazarettgasse 19/DG, 1090 Vienna, Austria
| | - Georg Watzek
- Oral Surgeon, Academy of Oral Implantology, Lazarettgasse 19/DG, 1090 Vienna, Austria
| | - Bernhard Pommer
- Oral Surgeon, Academy of Oral Implantology, Lazarettgasse 19/DG, 1090 Vienna, Austria
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Korabi R, Shemtov-Yona K, Rittel D. On stress/strain shielding and the material stiffness paradigm for dental implants. Clin Implant Dent Relat Res 2017; 19:935-943. [PMID: 28608498 DOI: 10.1111/cid.12509] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 05/22/2017] [Accepted: 05/22/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND Stress shielding considerations suggest that the dental implant material's compliance should be matched to that of the host bone. However, this belief has not been confirmed from a general perspective, either clinically or numerically. PURPOSE To characterize the influence of the implant stiffness on its functionality using the failure envelope concept that examines all possible combinations of mechanical load and application angle for selected stress, strain and displacement-based bone failure criteria. Those criteria represent bone yielding, remodeling, and implant primary stability, respectively MATERIALS AND METHODS: We performed numerical simulations to generate failure envelopes for all possible loading configurations of dental implants, with stiffness ranging from very low (polymer) to extremely high, through that of bone, titanium, and ceramics. RESULTS Irrespective of the failure criterion, stiffer implants allow for improved implant functionality. The latter reduces with increasing compliance, while the trabecular bone experiences higher strains, albeit of an overall small level. Micromotions remain quite small irrespective of the implant's stiffness. CONCLUSION The current paradigm favoring reduced implant material's stiffness out of concern for stress or strain shielding, or even excessive micromotions, is not supported by the present calculations, that point exactly to the opposite.
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Affiliation(s)
- Raoof Korabi
- Faculty of Mechanical Engineering, Technion, Haifa, 32000, Israel
| | | | - Daniel Rittel
- Faculty of Mechanical Engineering, Technion, Haifa, 32000, Israel
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The Failure Envelope Concept Applied To The Bone-Dental Implant System. Sci Rep 2017; 7:2051. [PMID: 28515495 PMCID: PMC5435678 DOI: 10.1038/s41598-017-02282-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 04/11/2017] [Indexed: 11/23/2022] Open
Abstract
Dental implants interact with the jawbone through their common interface. While the implant is an inert structure, the jawbone is a living one that reacts to mechanical stimuli. Setting aside mechanical failure considerations of the implant, the bone is the main component to be addressed. With most failure criteria being expressed in terms of stress or strain values, their fulfillment can mean structural flow or fracture. However, in addition to those effects, the bony structure is likely to react biologically to the applied loads by dissolution or remodeling, so that additional (strain-based) criteria must be taken into account. While the literature abounds in studies of particular loading configurations, e.g. angle and value of the applied load to the implant, a general study of the admissible implant loads is still missing. This paper introduces the concept of failure envelopes for the dental implant-jawbone system, thereby defining admissible combinations of vertical and lateral loads for various failure criteria of the jawbone. Those envelopes are compared in terms of conservatism, thereby providing a systematic comparison of the various failure criteria and their determination of the admissible loads.
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