Fatigue Life Of Dental Implants Research Articles

On the fatigue life of dental implants: Numerical and experimental investigation on configuration effect

Dental implants have seen widespread and successful use in recent years. Given their long-term application and the critical role of geometry in determining fracture and fatigue characteristics, fatigue assessments are of utmost importance for implant systems. In this study, nine dental implant system samples were subjected to testing in accordance with ISO 14801 standards. The tests included static evaluations to assess ultimate loads and fatigue tests conducted under loads of 270 N and 230 N at a frequency of 15 Hz, aimed at identifying fatigue failure locations and fatigue life. Fatigue life predictions and related calculations were carried out using Fe-safe software. The initial model featured a 22° angle for both the fixture and abutment. Subsequently, variations in abutment angles at 21° and 23° were considered while keeping the fixture angle at 22°. In the next phase, the fixture and abutment angles were set as identical, at 21° and 23°. The results unveiled that when the angles of the abutment and fixture matched, stress values decreased, and fatigue life increased. Conversely, models featuring abutment angles of 21° and 23°, with a 22° angle for the fixture, led to a 49.1 % increase in stress and a 36.9 % decrease in fatigue life compared to the primary model. Notably, in the case of the implant with a 23° angle for both abutment and fixture, the fatigue life reached its highest value at 10 million cycles. Conversely, the worst-case scenario was observed in the implant with a 21° abutment angle and a 23° fixture angle, with a fatigue life of 5.49 million cycles.

Effect of Loading Angles and Implant Lengths on the Static and Fatigue Fractures of Dental Implants.

Mechanical properties play a key role in the failure of dental implants. Dental implants require fatigue life testing before clinical application, but this process takes a lot of time. This study investigated the effect of various loading angles and implant lengths on the static fracture and fatigue life of dental implants. Implants with lengths of 9 mm and 11 mm were prepared. Static fracture tests and dynamic fatigue life tests were performed under three loading angles (30°, 40°, and 50°), and the level arm and bending moment were measured. After that, the fracture morphology and fracture mode of the implant were observed. The results showed that 9 mm length implants have a higher static failure load and can withstand greater bending moments, while 11 mm length implants have a longer fatigue life. In addition, as the loading angle increases, the static strength and bending moment decrease linearly, and the fatigue life shows an exponential decrease at a rate of three times. Increasing the loading angle reduces the time of the implant fatigue test, which may be an effective method to improve the efficiency of the experiment.

A comprehensive review of factors affecting fatigue life of dental implants

Abstract Materials used currently in dental implantology include pure titanium and titanium alloy namely- along with polymers and ceramics. Owing to their excellent mechanical properties such as lower modulus of elasticity, better fatigue strength, and higher corrosion resistance, they are more preferred for replacing a missing tooth in patients. The surface of dental implant plays a crucial role in determining the success for osseointegration with the human cells. Broadly classified, a successful implantation is the outcome of correlation between three factors, namely: osseointegration, fatigue endurance, and longevity of the implants subjected to masticatory forces offered by humans. The main objective of this review is to comprehensively understand the causes of fatigue and analyse through a mechanical aspect. The central theme of this article is the surface properties of a dental implant. A sequential breakdown of parameters such as dimensions of the implant, surface roughness, and surface coating thickness along with the advantages and disadvantages of surface treatment and surface coating methods on the fatigue life performance of implants have been presented. The experimental validity of all attributes mentioned in most of the literature have confirmed that fatigue failure is the most common mode of failure occurring in dental implants. Hence it becomes imperative to research the causes in depth and aim at controlling the factors to enhance the fatigue life of dental implants. This review gave an outline of the different attributes which affect fatigue failure in dental implants when subjected to masticatory forces.

Expert consensus on biomechanical research of dental implant

Current biomechanical research of dental implants focuses on the mechanical damage and enhancement mechanism of the implant-abutment interface as well as how to obtain better mechanical strength and longer fatigue life of dental implants. The mechanical properties of implants can be comprehensively evaluated by strain gauge analysis, photo elastic stress analysis, digital image correlation, finite element analysis, implant bone bonding strength test, and measurement of mechanical properties. Finite element analysis is the most common method for evaluating stress distribution in dental implants, and static pressure and fatigue tests are commonly used in mechanical strength test. This article reviews biomechanical research methods and evaluation indices of dental implants. Results provide methodology guidelines in the field of biomechanics by introducing principles, ranges of application, advantages, and limitations, thereby benefitting researchers in selecting suitable methods. The influencing factors of the experimental results are presented and discussed to provide implant design ideas for researchers.

Fatigue life and reliability evaluation for dental implants based on computer simulation and limited test data

Dental implants have been extensively utilized on edentulous patients for many years. The fatigue life of dental implants is critical for them being approved to use in human body because they are within the area of biomedicine. To perform a preliminary investigation of fatigue life of dental implants, this article reports a method of fatigue life estimation based on the combination of computer simulation and limited test data. The method is developed based on a probabilistic form of fatigue life given according to the properties of material fatigue strength. The procedure is carried out by shifting of the regression line (representing the fatigue–life curve) to the desired value of the probability of occurrence. Computer simulation includes both stress analysis and life estimation which are done using the ANSYS software. This estimation model offers a method for fatigue life evaluation and yields the life distribution in respect to the scatter of the cyclic properties of dental implants. Furthermore, the reliability of lifetime is calculated based on the probabilistic form. The purposes of this study are to predict fatigue life using a small amount of testing data and to provide a risk assessment for dental implants in use.

Effects of material properties and hole designs of the jig on the fatigue life of dental implants

A purpose of this paper is to analyze the effects of material properties and hole designs of the jig on fatigue test results of dental implants. An implant fatigue test method is described in ISO14801, which requires that the jig should firmly hold the implant and the elastic modulus of the jig should be more than 3 GPa. However, these requirements are insufficient to represent a dental implant in the jawbone as the fixture is osseointegrated in the jawbone that comprises of the cortical bone and the cancellous bone. In this paper, three different materials for the jig and two different hole designs of the jig for holding the implant were examined in FE simulations and fatigue tests. From the simulation and test results, the effects of material properties and the hole designs of the jig were evaluated in the light of fatigue life of dental implants.

Determining the Fatigue Life of Dental Implants

Dental implants are used to retain and support fixed and removable dental prostheses. In many clinical situations, local bone morphology requires dental implants that have a diameter that is significantly smaller than the typical implant diameters. In these cases, the fatigue life of the smaller diameter implants becomes a critical therapeutic parameter. However, this fatigue life depends on the implant itself, on the physical properties of the bone, as well as on other morphological characteristics that are patient dependent. In other words, this fatigue life varies greatly with each newly placed implant, but the capability to predict the fatigue life of dental implants does not exist today. In this paper, we present the first steps towards establishing such a methodology. We develop a finite element based fatigue model for rigidly mounted dental implants, and correlate its results with both analytical predictions as well as physical measurements. This implies that such a model can be used as a valid predictor of fatigue life of dental implants themselves, and can be used as a valuable implant design tool. Furthermore, we present the design of a cost effective device to measure the fatigue life of dental implants that can be either rigidly or bone mounted (in vitro). This device was used to measure the fatigue life of an initial sample of nine dental implants, and we show that the results predicted by the finite element model correlated well with our initial experimental results.

Measurement of the Fatigue Life of Mini Dental Implants: A Pilot Study

The fatigue life of mini or small-diameter dental implants is of particular interest because these implants are used to retain and support fixed and removable dental prostheses. The fatigue life of an implant depends on both the implant itself as well as on the physical properties of the bone. However, the capability to predict the fatigue life of a newly placed implant is currently inexistent. This pilot study represents the first step in developing such a methodology and focuses on the design of a cost-effective device to measure the fatigue life of a dental implant. In our measurements, the implant has been mounted in an essentially rigid support, but test specimens can also be bone mounted in vitro. Furthermore, we developed a finite element-based computer model capable of predicting the corresponding fatigue life. The finite element analysis was performed in ABAQUS, and the results predicted by the model correlated fairly well with our initial experimental results. Most of the 2-mm diameter implants fractured after more than a million cycles.

Analyses of fractured implant fixture after prolonged implantation

Although fortunately rare, fracture of implants causes significant problems for both clinicians and patients. The major cause of a fractured implant may be corrosion fatigue fracture. To investigate how to increase the fatigue life and corrosion resistance of dental implants, the surface morphology of six Steri-Oss fractured implants was analyzed. The period of implantation after loading in patient jaws varied between 23 months and 37 months. The topography and surface chemical composition were studied with electron probe micro-analysis (point mapping, energy dispersive x-ray spectroscopy) and field emission scanning electron microscopy. All samples were fractured at the screw root and the crest formed a keen-edged shape. The five samples were fractured at the first thread of the fixture and one sample at the third thread of fixture. The fatigue cracks were mainly nucleated and grown at scratches occurring for the screw root and crest formation and the cervix portion of the implant having a small curvature. The pits were nucleated in the vicinity of inclusions such as SiO2 and corrosion fatigue cracking was predominantly propagated. Corrosion products were found on the opposite side of the starting point of corrosion fatigue crack. From observations of fatigue striations, it is possible to predict the life time of fractured implants and estimate the cleavage fracture and dimple fracture of implants. In this study, analysis of fractured surfaces revealed the characteristics of the implant materials, problems of design, fatigue life, and manufacturing process. In order to protect against corrosion fatigue fractures and prolong the fatigue life of dental implants, we must consider the implant design, implant manufacturing, and surface treatment of the implant materials.