Possibilities of Application of 3D Printing in Contemporary Dentistry

Development of 3D printing in medical and dental applications has advanced significantly in recent years. 3D technologies are commercially available, i.e. 3D printing and 3D scanning, allowing dentists to easily scan and record state of hard and soft tissues following 3D printing of dental models or supporting structures-like surgical guides and aligners. Thereafter, dental technicians work with these 3D printed dental models of upper and lower jaw, as they previously have been working with plaster models, and because of attainable high dimensional accuracy of these dental models 3D printing technology found its way in dentistry and will improve both in today’s application and will expand the range of possible applications in dentistry. The aim of this paper is to present stereolithography (SLA) 3D printing technology of dental working models. SLA technology is mainly applied in rapid prototyping, but due to exceptional dimensional accuracy it easily found its application in dentistry, where accuracy is of utmost importance. SLA technology works in layer-by-layer manner, using UV lasers to polymerize, i.e. solidify, liquid photopolymer resin placed in a vat. Only accuracy issue of this technology occurs when using more layers to build a model, i.e. if an error appears at a certain layer it will stack on succeeding layers and will create notable dimensional mismatch. Materials used in this research are grey standard resin, dental model resin, long-term biocompatible clear resin and biocompatible photopolymer resin. Created dental models are used for planning and making dental crowns and bridges

Characterization of 3D Printed Parts

3D printing as digital fabrication technology became widely popular and used due to its ease in production and customization of any type of design in various fields of industry, medicine, or research. Different printing processes are based on making an object by deposition of material layer by layer, from previously created CAD model. Quality of 3D printed parts is dependent on many parameters such as chemical composition of used materials, printing parameters (infill percentage, infill pattern, building orientation, raster angle,..), thermal behaviour during and after printing processes, aging effect, mechanical properties (static and dynamic analysis), accuracy of printed parts, morphology and topology. With regard to the area of characteristics, which should be examined, different standards, procedures and equipment are employed. In this context, it is challenging task to link various parameters to obtain the best part performances. Given the large number of different possibilities in testing of final 3D printed product, understanding the influential parameters of structure of the material and final part is essential. This paper presents an overview of characterization methods that can be used in order to observe morphology and topology of printed parts

FDM Printing Technology Applications in Dentistry

In recent years, 3D printing technology is rapidly developing and constantly leading to new applications. One of the areas which have widely accepted benefits from 3D printing in dentistry, because of its demands to have personalized and customized dental products and appliances. Mostly used 3D printing methods in dentistry include stereolithography (SLA), selective laser sintering (SLS), fused deposition modelling (FDM), and digital light processing (DLP). This paper presents FDM printing technology and its applications in everyday dental practice. FDM is a widely available technology, easy to be installed, with a relatively reliable quality printed parts. In the fused deposition modelling process, objects are created by layering different types of thermoplastic polymeric filament materials, such as polylactic acid (PLA). The polymer material is extruded through a nozzle device, where a computer controls the temperature and movement of the material. Material is in a semiliquid state, it hardness after the extrusion, and bonds to the previous layer. Parameters for printing that need to be defined are numerous, and dependant on every particular task. Experience from praxis shows that FDM is used for the production and prototyping of pattern of the complete denture, custom bite registrations, basic proof-of-concept models, simple, low-cost prototyping anatomical parts. Disadvantages of this technology are rough surface finish, inhomogeneous density, longer printing time. However, future innovations will alleviate some of the present disadvantages, by, for example, reducing steps that are needed to get the end product

Procedure for Creating Personalized Geometrical Models of the Human Mandible and Corresponding Implants

The greatest challenge in engineering of human mandible implants lies in its customization for each patient individually, by adapting them to the patient's anatomical, morphological and physiological characteristics. This customization maximizes the efficiency of the patient's health recovery process. The application of anatomically shaped and personalized bone endoprosthesis, fixation plate and scaffold models bring great improvement to the clinical practice in maxillofacial surgery. It ensures that implant meets the biomechanical and dentofacial aesthetic requirements and, ultimately, reduces complications during recovery. In order to create such implants, novel procedure based on personalized models of mandible and its parts, and also plates and scaffold implants is presented in this paper. Design procedures for the creation of the personalized models are based on the application of Method of Anatomical Features, which has been already applied for the creation of geometrical models of human bones. This procedure improves pre-surgical planning, enables better execution of surgical intervention, and as a consequence improves patient recovery processes

Influence of second-phase particles on fracture behavior of PLA and advanced PLA-X material

Most widespread materials in Additive Manufacturing are PLA (PolyLactic Acid) and ABS (Acrylonitrile Butadiene Styrene), which are dissimilar materials in terms of printing abilities and mechanical properties. PLA material originates from renewable resources making it better solution for environment in comparison with petroleum-based ABS material. Addition of second-phase particles to polymer matrix may have a substantial influence on mechanical properties of created material. Subject of this paper are natural PLA material and advanced PLA material with addition of second-phase particles (''PLA-X'') which has similar mechanical properties as ABS material, making it a perfect PLA based substitute. Tensile tests are conducted according to ISO 527-2 standard. Subject of this paper is the analysis of fracture behaviour of PLA and advanced PLA-X material, which ranges from brittle to formation of large craze zones before fracture. Analysis is conducted for five batches of both materials, with variation in printing parameters. The main focus of this research was to evaluate the influence of second-phase particles on fracture behaviour of PLA and advanced PLA-X material

Design Aspects of Hip Implant Made of Ti-6Al-4V Extra Low Interstitials Alloy

The main concerns in design of hip implants are fracture and fatigue related issues. In this paper, reverse engineering is used to redesign a hip implant produced by precision casting, using Ti6Al4V Extra Low Interstitials (ELI) alloy. As the most critical part, hip neck has been in the focus of this analysis, keeping in mind that the lower the thickness is, the higher the movement of joint may be, but affecting its structural integrity at the same time. Thus, 5 different models are created with different neck thickness and analyzed by using the Finite Element Method (FEM) for stress-strain calculation and extended FEM (XFEM) for fatigue crack growth

Integrity assessment of reverse engineered ti-6al-4v eli total hip replacement implant

Total hip replacement implants are used as an artificial replacement for disfunctional hips in order to sustain joint movement. Chosen material and design of total hip replacement are the most influential factors for artificial joint utilization. Selected total hip replacement is obtained by precision casting method, made from Ti6Al4V ELI (Extra Low Interstitials) alloy. In order to acquire a geometrical model of chosen implant, the 3D scanner is used and an obtained point cloud (PC), then exploited for reverse engineering to a CAD model. The neck thickness of implant affects angle of movement of the joint and structural integrity. Reducing the thickness of the neck section results in higher movement of the joint, but inversely affects its structural integrity. The 3D scanned implant has a neck thickness of 14.6 mm, and data from literature suggest that the best movement angle is for 9 mm thickness of the implant. In order to redesign the available implant, five different models with a neck thickness between 9 and 14.6 mm are made. Obtained results show the thickness effects the stress distribution in a critical area

Influence of second-phase particles on fracture behavior of PLA and advanced PLA-X material

Most widespread materials in Additive Manufacturing are PLA (PolyLactic Acid) and ABS (Acrylonitrile Butadiene Styrene), which are dissimilar materials in terms of printing abilities and mechanical properties. PLA material originates from renewable resources making it better solution for environment in comparison with petroleum-based ABS material. Addition of second-phase particles to polymer matrix may have a substantial influence on mechanical properties of created material. Subject of this paper are natural PLA material and advanced PLA material with addition of second-phase particles (''PLA-X'') which has similar mechanical properties as ABS material, making it a perfect PLA based substitute. Tensile tests are conducted according to ISO 527-2 standard. Subject of this paper is the analysis of fracture behaviour of PLA and advanced PLA-X material, which ranges from brittle to formation of large craze zones before fracture. Analysis is conducted for five batches of both materials, with variation in printing parameters. The main focus of this research was to evaluate the influence of second-phase particles on fracture behaviour of PLA and advanced PLA-X material

Design Aspects of Hip Implant Made of Ti-6Al-4V Extra Low Interstitials Alloy

The main concerns in design of hip implants are fracture and fatigue related issues. In this paper, reverse engineering is used to redesign a hip implant produced by precision casting, using Ti6Al4V Extra Low Interstitials (ELI) alloy. As the most critical part, hip neck has been in the focus of this analysis, keeping in mind that the lower the thickness is, the higher the movement of joint may be, but affecting its structural integrity at the same time. Thus, 5 different models are created with different neck thickness and analyzed by using the Finite Element Method (FEM) for stress-strain calculation and extended FEM (XFEM) for fatigue crack growth

Numerical analysis of stress distribution in total hip replacement implant

Total hip replacement implants represent permanent implants and require large bone and cartilage removal during implantation. Revision would affect joint capability to sustain load, which makes this procedure irreversible. During exploitation, i.e. everyday activities, implants are subjected to dynamic loading. Thereby, these structures are prone to failure by fatigue. Highest stress states on total hip replacement implants are present in the neck area of the implant, which is a position of crack initiation. Under loading the implant neck exhibits tension and compression zones. Crack initiation in the neck side under tension would lead to crack opening and certain fracture. Implants are examined by experimental and numerical methods. The most common numerical method is finite element method (FEM) used to simulate different loading conditions. In this paper numerical analysis of stress distribution in the neck area is performed on a specific implant. Four numerical models are created in order to show how certain design solutions influence the stress distribution in the neck area