Design Of Dental Implants Research Articles

Zirconia Dental Implant Designs and Surface Modifications: A Narrative Review.

Titanium currently has a well-established position as the gold standard for manufacturing dental implants; however, it is not free of flaws. Mentions of possible soft-tissue discoloration, corrosion, and possible allergic reactions have led to the development of zirconia dental implants. Various techniques for the surface modification of titanium have been applied to increase titanium implants' ability to osseointegrate. Similarly, to achieve the best possible results, zirconia dental implants have also had their surface modified to promote proper healing and satisfactory long-term results. Despite zirconium oxide being a ceramic material, not simply a metal, there have been mentions of it being susceptible to corrosion too. In this article, we aim to review the literature available on zirconia implants, the available techniques for the surface modification of zirconia, and the effects of these techniques on zirconia's biological properties. Zirconia's biocompatibility and ability to osseointegrate appears unquestionably good. Despite some of its mechanical properties being, factually, inferior to those of titanium, the benefits seem to outweigh the drawbacks. Zirconia implants show very good success rates in clinical research. This is partially due to available methods of surface treatment, including nanotopography alterations, which allow for improved wettability, bone-to-implant contact, and osteointegration in general.

Homogenized finite element simulations can predict the primary stability of dental implants in human jawbone

Adequate primary stability is a pre-requisite for the osseointegration and long-term success of dental implants. Primary stability depends essentially on the bone mechanical integrity at the implantation site. Clinically, a qualitative evaluation can be made on medical images, but finite element (FE) simulations can assess the primary stability of a bone-implant construct quantitatively based on high-resolution CT images. However, FE models lack experimental validation on clinically relevant bone anatomy. The aim of this study is to validate such an FE model on human jawbones. Forty-seven bone biopsies were extracted from human cadaveric jawbones. Dental implants of two sizes (Ø3.5 mm and Ø4.0 mm) were inserted and the constructs were subjected to a quasi-static bending-compression loading protocol. Those mechanical tests were replicated with sample-specific non-linear homogenized FE models. Bone was modeled with an elastoplastic constitutive law that included damage. Density-based material properties were mapped based on μCT images of the bone samples. The experimental ultimate load was better predicted by FE (R2 = 0.83) than by peri-implant bone density (R2 = 0.54). Unlike bone density, the simulations were also able to capture the effect of implant diameter. The primary stability of a dental implant in human jawbones can be predicted quantitatively with FE simulations. This method may be used for improving the design and insertion protocols of dental implants.

Comparative Study of the Influence of Dental Implant Design on the Stress and Strain Distribution using the Finite Element Method.

One emerging and important research method for biomechanical assessments in biological investigations is the finite element analysis (FEA). It is the best technique for simulating intricate structures and examining their mechanical characteristics. This study was conducted to compare the V-shaped design and square thread design regarding their influence on the stress and strain distribution using the finite element method. Forty dental implants with two different designs were used. These designs were V-shaped design and square design. Utilizing Creo 2.0, cortical bone, cancellous bone, and implants were modeled. FEM analysis was performed on forty model assemblies. It was observed that mean load 1 values for squared thread design were lesser as compared to V-shaped thread design at coronal one-third middle one-third and apical one-third in the cancellous bone as well as implant surface. The design of implant is an important factor influencing the stress and strain distribution using the finite element method with a square design showing reduced concentration.

Evaluating the effect of functionally graded materials on bone remodeling around dental implants

ObjectivesThis study evaluates the potential for osseointegration and remodeling of customized dental implants made from Titanium-Hydroxyapatite Functionally Graded Material (Ti-HAP FGM) with optimized geometry, using the finite element method (FEM). MethodsThe study utilized CT scan images to model and assemble various geometrical designs of dental implants in a mandibular slice. The mechanical properties of Ti-HAP FGMs were computed by varying volume fractions (VF) of hydroxyapatite (0–20%), and a bone remodeling algorithm was used to evaluate the biomechanical characteristics of the ultimate bone configuration in the peri-implant tissue. ResultsThe findings of the FEA reveal that osseointegration improves with changes in the density and mechanical properties of the bone surrounding Ti-HAP implants, which are influenced by the varying VF of hydroxyapatite in the FGM. SignificanceIncreasing the hydroxyapatite fraction improves osseointegration, and appropriate length and diameter selection of Ti-HAP dental implants contribute to their stability and longevity.

Muscle and joint mechanics during maximum force biting following total temporomandibular joint replacement surgery

Total temporomandibular joint replacement (TMJR) surgery is the established treatment for severe temporomandibular joint disorders. While TMJR surgery is known to increase mouth-opening capacity, reduce pain and improve quality of life, little is known about post-surgical jaw function during activities of daily living such as biting and chewing. The aim of this study was to use subject-specific 3D bite force measurements to evaluate the magnitude and direction of joint loading in unilateral total TMJR patients and compare these data to those in healthy control subjects. An optoelectronic tracking system was used to measure jaw kinematics while biting a rubber sample for 5 unilateral total TMJR patients and 8 controls. Finite element simulations driven by the measured kinematics were employed to calculate the resultant bite force generated when compressing the rubber between teeth during biting tasks. Subject-specific musculoskeletal models were subsequently used to calculate muscle and TMJ loading. Unilateral total TMJR patients generated a bite force of 249.6 ± 24.4 N and 164.2 ± 62.3 N when biting on the contralateral and ipsilateral molars, respectively. In contrast, controls generated a bite force of 317.1 ± 206.6 N. Unilateral total TMJR patients biting on the contralateral molars had a significantly higher lateral TMJ force direction (median difference: 63.6°, p = 0.028) and a significantly lower ratio of working TMJ force to bite force (median difference: 0.17, p = 0.049) than controls. Results of this study may guide TMJ prosthesis design and evaluation of dental implants.

Design and development of dental implants

Dental implants have emerged as an important treatment in modern dentistry for repairing lost teeth, providing patients with enhanced oral function, aesthetics, and overall quality of life. An optimal dental implant minimizes peak stress values at the interface between the implant and the bone while optimizing anchoring strength in the human jawbone under specified standard loads. Implant design controls stress concentration at the bone-implant interface, which influences the biological reaction of the bone. This paper models an optimal thread design to minimize stress distribution surrounding the jawbone. Cylindrical dental implants with micro-threading and square threading improve anchoring and reduce screw loosening, thereby optimizing performance. Biomaterials used in the implant also play a major role. Ni-Ti shape memory alloys (SMAs) have unique characteristics such as biocompatibility, excellent wear and corrosion resistance, and functional features like superelasticity and the shape memory effect, making them suitable for a wide range of biomedical applications. Dental implant design has focused on modifying the shape, size, material, and surface topography to meet market demands. Consequently, the modeling of a dental implant with an improved threading type in the implant body has been accomplished with precise dimensions using SolidWorks 3D CAD software. COMSOL Multiphysics, based on finite element analysis, is then used to analyze the biomechanical properties by importing an STL file from SolidWorks. Several biomechanical factors affect the effectiveness of dental implants, including the nature of loading, the properties of the material used, the shape and geometry of the implants, the quantity and quality of bone around the implants, the surgical technique, and the degree of rapid integration of the implant surface with the jawbone.

3D printing, modelling and simulation for dental implant: A comprehensive review

The implementation of three-dimensional printing technology has revolutionised dentistry over the past decade. The desired object is scanned by a 3D scanner or built using computer-aided design (CAD)/computer-aided manufacturing (CAM) software. CAD designs of dental implants can be analysed by the finite element method (FEM). Finite element analysis (FEA) is done by discretising the geometrically developed model into smaller and simpler elements and analysing the 3D model using different boundary conditions on different nodes. Depending on the materials of choice, various printing methods are available, such as selective laser sintering (SLS), stereolithography, fused deposition modelling, and laminated object manufacturing. Dental implants are designed with the help of different biomaterials, such as polymers, metals, and ceramics. Clinicians should know the latest implant materials for successful implant therapy. This review article investigates 3D printing on various dental implants, designs, simulations, and limitations. The last part of the article discusses different properties of the implant materials used in the designs.

Constitutive models based on titanium and its alloys for studying deformation and stresses in dental prosthesis: A comprehensive review

For optimized design and better functioning of dental implants, researchers to a great extent have used the finite element method (FEM) as a computational/numerical tool. It appears from the review that, despite a significant amount of success in understanding the deformation and stress fields generated in dental implants and its surrounding bone, there are still several inadequacies prevailing in the constitutive models used in dentistry. Therefore, the theoretical/computational basis of dental prosthesis’s deformation and stress analysis needs further improvement. To better understand the deformation and stresses produced in dental implants and their surrounding bone, the present work summarizes and discusses various constitutive models for titanium and its alloys as an implant material developed over the past few decades. The accomplishments and shortcomings of the current models are discussed. In addition, for completeness, the present study also summaries the effects of other factors in optimizing the dental implant. Critical findings indicate that longer dental implants effectively reduce stress gradients in the cortical peri-implant region. Threaded implants offer notable benefits, such as reduced bone stresses, enhanced osseointegration surface, and minimum slippage risk at the bone-implant junction. To further improve dental implant success rates, it is essential to consider the impact of dynamic loading and the viscoelastic behaviour of surrounding tissues. The use of porous implant structures shows promise in reducing maximum stress in cortical bone and enhancing load distribution, ultimately ameliorating the adverse effects of stress shielding in dental implant procedures. Further, some guidelines and research gaps have also been highlighted to develop more realistic time-dependent constitutive models of both implants and their surrounding bones.

Design and additive manufacturing of root analogue dental implants: A comprehensive review

Dental implants are key components in treating dental diseases and correcting dental defects, and they have gained widespread utilisation in various medical operations. However, traditional screw thread implants have been associated with certain drawbacks, including issues such as poor consistency with the alveolar bone and difficulty in customisation. Root analogue implants (RAI) are considered a promising substitute; however, they are not widely applied until now as their geometry design needs more improvements. The utilisation of porous structures, such as triply periodic minimal surfaces, in dental implants can reduce the elastic modulus, increase interconnectivity, and allow for strictly controllable structural characteristics. To achieve optimal initial and long-term stability, it is essential to have a moderate geometry that promotes a proper fit between the dental implants and the natural bone. Different porous and macro-retention structures of RAIs have been investigated due to the above two demands. However, owing to their complex porosity, such structures can only be effectively manufactured using additive manufacturing techniques. Various additive manufacturing technologies have been employed for the fabrication of dental implants and have provided good surface quality and mechanical properties. In vivo tests have demonstrated that their performance is similar to that of commercial implants fabricated using subtractive manufacturing techniques. In this review, we comprehensively examine the design concepts and processes involved in the development of dental implants, along with the application of additive manufacturing methods for their fabrication, while also offering recommendations for the future advancement of dental implant designs.

Investigation on primary stability of dental implants through considering peri-implant bone damage, caused by small and large deformations: A validated non-linear micro finite element study

Primary stability of a dental implant is defined as its ability to resist the applied load without showing excessive damage in peri-implant bone, which is a prerequisite for secondary stability, and consequently for implantation success. The main goal of this study was to develop a validated micro-finite element (μFE) approach to assess the primary stability of dental implants in terms of stiffness, stiffness reduction, and irreversible displacement of the bone-implant system, subjected to an increasing step-wise quasi-static compressive loading-unloading test. The μFE models were generated based on the μCT images of bone, taken from extracted bovine tibia trabecular bone samples after drilling and implantation. A tissue constitutive model was considered for trabecular bone by describing elasto-plasticity with a modified von Mises yield criterion and element deletion technique to account for trabecular bone damage behavior. Then, the obtained force-displacement curves from the simulation were compared with the in-vitro mechanical test curves to evaluate the validity of the model. The results showed that the proposed μFE model could be properly predict the bone-implant system mechanical response in terms of irreversible displacement (R2 = 0.99), stiffness (R2 = 0.77), and stiffness reduction (R2 = 0.72) of the bone-implant construct for all the applied displacements without a significant difference from the unit slope and zero intercept of the QQ-plot (p-value<0.05). Moreover, a qualitative agreement was seen between the peri-implant bone damage predicted by the μFE model and the observed from μCT images. The adopted methodology used in this study can predict the mechanical failure response of the bone-implant system, which can be employed as a representative tool to study the effects of various dental implant design parameters on the primary stability with the ultimate goal of optimizing dental implants design.

Optimization and innovative design of dental implants under dynamic finite element analysis

ABSTRACT Dental implants’ usage life and strength are critical factors for implant patients. This paper examines the optimization of dental implant threads by modifying the C-Tech implant system model to ascertain thread design’s impact on micromotion through finite element analysis (FEA). The fundamental measurements of the redesigned C-Tech implant system are established by dynamic (FEA). Six implant parameters are chosen as the control factors to be advanced. Experimental simulations are built using a uniform design (UD) method. The dynamic FEA tool ANSYS/LS-DYNA is utilized for each experimental simulation to identify the maximal micromotion in the modified C-Tech implant system. The optimum design model is acquired by minimizing the micromotion by applying the Kriging interpolation (KGI) and genetic algorithm (GA). The improved design has a micromotion of 12.19 µm, as opposed to the original design’s micromotion of 38.11 µm. The improvement rate is 68.02%. Finally, the following innovative design is to add a secondary thread to the implant body. After conducting simulations, the micromotion is reduced to 4.72 µm. Further, it shows a 61.28% improvement compared with the optimization design version and an 87.62% improvement compared with the primary implants.

Investigation of the Influence of Roughness and Dental Implant Design on Primary Stability via Analysis of Insertion Torque and Implant Stability Quotient: An In Vitro Study.

In the placement of dental implants, the primary fixation between the dental implant and the bone is of great importance and corresponds to compressive mechanical fixation that aims to prevent micromovement of the implant. The aim of this research was to determine the role of roughness and the type of dental implant (tissue-level or bone-level) in implant stability, measured using resonance frequency analysis (RFA) and insertion torque (IT). We analyzed 234 titanium dental implants, placed in fresh calf ribs, at the half-tissue level and half-bone level. The implant surface was subjected to grit-blasting treatments with alumina particles of 120, 300, and 600 μm at a projection pressure of 2.5 bar, resulting in three types of roughness. Roughness was determined via optical interferometry. The wettability of the surfaces was also determined. Implant stability was measured using a high-precision torquemeter to obtain IT, and RFA was used to determine the implant stability quotient (ISQ). The results show that rough surfaces with Sa values of 0.5 to 4 μm do not affect the primary stability. However, the type of implant is important; bone-level implants obtained the highest primary stability values. A good correlation between the primary stability values obtained via IT and ISQ was demonstrated. New in vivo studies are necessary to know whether these results can be maintained in the long term.

Porous structure design and properties of dental implants

At present, selective laser melting (SLM) 3D printing technology can accurately control the internal pore structure and complex cell shape. Three types of reticulated meshes with cubic, G7 and composite structure cell shapes were fabricated by the SLM 3D printing technology using Ti–6Al–4V alloy powders. The bone stresses around the implant and the stresses in the implant were analyzed by ANSYS finite element software, which comprehensively evaluated the effect of porous dental implants with different spatial porosity characteristics on osseointegration. The results show that porous dental implants with composite structure of pore characteristics have improved mechanical and biological properties and can better promote the growth and integration of bone tissue.

Relevant Aspects of the Dental Implant Design on the Insertion Torque, Resonance Frequency Analysis (RFA) and Micromobility: An In Vitro Study.

The major problems for the osseointegration of dental implants are the loosening of the screw that fixes the dental implant to the abutment and the micromovements that are generated when mechanical loads are applied. In this work, torque differences in the tightening and loosening of the connection screws after 1 cycle, 10 cycles and 1000 cycles for 4 dental implants with 2 external and 2 internal connections were analyzed. The loosening of 240 implants (60 for each system) was determined using high-precision torsimeters and an electromechanical testing machine. A total of 60 dental implants for each of the 4 systems were inserted into fresh bovine bone to determine the micromovements. The implant stability values (ISQ) were determined by RFA. The mechanical loads were performed at 30° from 20 N to 200 N. By means of the Q-star technique, the micromovements were determined. It was observed that, for a few cycles, the loosening of the screw did not exceed a loss of tightening of 10% for both connections. However, for 1000 cycles, the loss for the external connection was around 20% and for the internal connection it was 13%. The micromovements showed a lineal increase with the applied load for the implant systems studied. An external connection presented greater micromotions for each level of applied load and lower ISQ values than internal ones. An excellent lineal correlation between the ISQ and micromobility was observed. These results may be very useful for clinicians in the selection of the type of dental implant, depending on the masticatory load of the patient as well as the consequences of the insertion torque of the dental implant and its revisions.

Contemporary Trends in Dental Implants

A high number of patients have one or more missing tooth and it is estimated that one in four world subjects over the age of 74 have lost all their natural teeth. Many options exist to replace missing teeth but dental implants have become one of the most used biomaterial to replace one (or more) missing tooth over the last decades. Therefore, the use of dental implants is also a common practice. Although research on dental implant de­signs, materials and techniques has increased in the past few years and is expected to expand in the future, there is still a lot of work involved in the use of better biomaterials, implant design, surface modification and functionalization of surfaces to improve the long-term outcomes of the treatment. This paper provides a brief history and evolution of dental implants. It also describes the types of implants that have been developed, and the parameters that are presently used in the design of dental implants. Finally, it describes the trends that are employed to improve dental implant surfaces, and current technologies used for the analysis and design of the implants. Keywords: Dental implants, History, Design, Surfaces, Osseointegration, Biopolymers.

Measurement of bone damage caused by quasi-static compressive loading-unloading to explore dental implants stability: Simultaneous use of in-vitro tests, μ-CT images, and digital volume correlation

Primary stability of dental implants is the initial mechanical engagement of the implant with its adjacent bone. Implantation and the subsequent loading may cause mechanical damage in the peripheral bone, which ultimately reduces the stability of the implant. This study aimed at evaluating primary stability of dental implants through applying stepwise compressive displacement-controlled, loading-unloading cycles to obtain overall stiffness and dissipated energy of the bone-implant structure; and quantifying induced plastic strains in surrounding bone using digital volume correlation (DVC) method, through comparing μCT images in different loading steps. To this end, dental implants were inserted into the cylindrical trabecular bones, then the bone-implant structure was undergone step-wise loading-unloading cycles, and μCT images were taken in some particular steps, then comparison was made between undeformed and deformed configurations using DVC to quantify plastic strain within the trabecular bone. Comparing stiffness reduction and dissipated energy values in different loading steps, obtained from the force-displacement curve in each loading step, revealed that the maximum displacement of 0.16 mm can be deemed as a safe threshold above which damages in peri-implant bone started to increase considerably (p < 0.05). In addition, it was found here that peri-implant bone strain linearly increased with decreasing bone-implant stiffness (p < 0.05). Moreover, strain concentration in peri-implant bone region showed that the plastic strain in trabecular bone spread up to a distance of about 2.5 mm away from the implant surface. Research of this kind can be used to optimize the design of dental implants, with the ultimate goal of improving their stability, also to validate in-silico models, e.g., micro-finite element models, which can help gain a deeper understanding of bone-implant construct behavior.

Influence of the Residual Ridge Widths and Implant Thread Designs on Implant Positioning Using Static Implant Guided Surgery.

Aggressive implant macrothread designs have been widely used. However, the effects of the aggressive thread design on the accuracy of static guided surgery, especially in a case of narrow residual ridge, have not been well-studied. The aim of this study was to evaluate the effects of two different implant macrothread designs and the residual ridge widths on the accuracy of tooth-supported static guided implant surgery. Forty implant fixtures with two different macrodesigns: a conventional thread design bone level tapered (BLT), and an aggressive thread design bone level tapered (BLX) were placed in 40 simulated polyurethane models with narrow and wide residual ridges. The placed implant positions were compared with the planned implant position and angulational deviation, as well as three-dimensional (3D) deviations at the entry and apex of the implant were measured. One-way ANOVA with Tukey's multiple comparisons (ɑ = 0.05) were used to determine level of significance between the mean and variance deviation values. 95% confidence intervals and box plots were used to demonstrate the means and ranges of precision. In terms of angulational deviation, there was no statistically significant difference in the mean deviations for both types of implants, p = 1.55 and p = 0.84 for wide and narrow ridge groups, respectively. However, the range of deviation was much larger in the narrow ridge of the BLX group compared to the BLT group. In both narrow ridge and wide ridge, the BLX group had lower mean 3D deviation values at both the entry and the apex with statistically significant differences for both entry point of the wide ridge (p = 0.027) and narrow ridge (p = 0.022) as well as at the apex of the wide ridge (p = 0.006) but not the apex of the narrow ridge (p = 0.142). The aggressive larger thread design of dental implants may influence the accuracy of implant placement more than the ridge dimension.

Rational Design and Characterisation of Novel Mono- and Bimetallic Antibacterial Linde Type A Zeolite Materials.

The development of antimicrobial devices and surfaces requires the setup of suitable materials, able to store and release active principles. In this context, zeolites, which are microporous aluminosilicate minerals, hold great promise, since they are able to serve as a reservoir for metal-ions with antimicrobial properties. Here, we report on the preparation of Linde Type A zeolites, partially exchanged with combinations of metal-ions (Ag+, Cu2+, Zn2+) at different loadings (0.1–11.9 wt.%). We combine X-ray fluorescence, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction to monitor the metal-ion contents, distribution, and conservation of the zeolite structure after exchange. Then, we evaluate their antimicrobial activity, using agar dilution and optical-density monitoring of Escherichia coli cultures. The results indicate that silver-loaded materials are at least 70-fold more active than the copper-, zinc-, and non-exchanged ones. Moreover, zeolites loaded with lower Ag+ concentrations remain active down to 0.1 wt.%, and their activities are directly proportional to the total Ag content. Sequential exchanges with two metal ions (Ag+ and either Cu2+, Zn2+) display synergetic or antagonist effects, depending on the quantity of the second metal. Altogether, this work shows that, by combining analytical and quantitative methods, it is possible to fine-tune the composition of bi-metal-exchanged zeolites, in order to maximise their antimicrobial potential, opening new ways for the development of next-generation composite zeolite-containing antimicrobial materials, with potential applications for the design of dental or bone implants, as well as biomedical devices and pharmaceutical products.

Biomechanical Properties of Bone and Mucosa for Design and Application of Dental Implants.

Dental implants’ success comprises their proper stability and adherence to different oral tissues (integration). The implant is exposed to different mechanical stresses from swallowing, mastication and parafunctions for a normal tooth, leading to the simultaneous mechanical movement and deformation of the whole structure. The knowledge of the mechanical properties of the bone and gingival tissues in normal and pathological conditions is very important for the successful conception of dental implants and for clinical practice to access and prevent potential failures and complications originating from incorrect mechanical factors’ combinations. The challenge is that many reported biomechanical properties of these tissues are substantially scattered. This study carries out a critical analysis of known data on mechanical properties of bone and oral soft tissues, suggests more convenient computation methods incorporating invariant parameters and non-linearity with tissues anisotropy, and applies a consistent use of these properties for in silico design and the application of dental implants. Results show the advantages of this approach in analysis and visualization of stress and strain components with potential translation to dental implantology.

Assessment of Titanate Nanolayers in Terms of Their Physicochemical and Biological Properties.

The surface modification of titanium substrates and its alloys in order to improve their osseointegration properties is one of widely studied issues related to the design and production of modern orthopedic and dental implants. In this paper, we discuss the results concerning Ti6Al4V substrate surface modification by (a) alkaline treatment with a 7 M NaOH solution, and (b) production of a porous coating (anodic oxidation with the use of potential U = 5 V) and then treating its surface in the abovementioned alkaline solution. We compared the apatite-forming ability of unmodified and surface-modified titanium alloy in simulated body fluid (SBF) for 1–4 weeks. Analysis of the X-ray diffraction patterns of synthesized coatings allowed their structure characterization before and after immersing in SBF. The obtained nanolayers were studied using Raman spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), and scanning electron microscopy (SEM) images. Elemental analysis was carried out using X-ray energy dispersion spectroscopy (SEM EDX). Wettability and biointegration activity (on the basis of the degree of integration of MG-63 osteoblast-like cells, L929 fibroblasts, and adipose-derived mesenchymal stem cells cultured in vitro on the sample surface) were also evaluated. The obtained results proved that the surfaces of Ti6Al4V and Ti6Al4V covered by TiO2 nanoporous coatings, which were modified by titanate layers, promote apatite formation in the environment of body fluids and possess optimal biointegration properties for fibroblasts and osteoblasts.