Dynamic mechanical properties of oral mucosa: comparison with polymeric soft denture liners.

The purpose of this work was to characterize the viscoelastic behaviour of oral mucosa and compare it with the dynamic mechanical properties of different soft liners. For this purpose, a sample of pig oral mucosa and six commercialized soft liner samples have been investigated. A comparison was also carried with the first suitable hard rubber for dental prosthetics: vulcanite. Creep recovery (CR) and dynamic mechanical analysis (DMA)have been used to determine the mechanical modulus of oral mucosa and soft liners respectively. The Poisson ratio is used to compare mucosa bulk modulus and soft liner shear modulus. The biomechanical concept of conventional complete dentures needs a good adjustment of dynamic mechanical impedance between the base and oral mucosa. The viscoelastic mechanical property of the oral mucosa as a referent biopolymer has been confirmed in vitro. The modulus value, adjusted for old patients in physiological conditions, is in the order of 3 MPa. This study underlines the plasticization effect of absorbed water on the mechanical properties of the underlying tissue. This study allows us to define some characteristics of the most adapted biomaterial according to the clinical exigency. The required biomaterial must display the following properties: compatibility and chemical resistance with biological environment perpetuated mechanical properties during physiological conditions and clinical use, good adjustment of dynamic mechanical impedance with supporting mucosa and easy sample processing

A case study of technology transfer: Rehabilitative engineering at Rancho Los Amigos Hospital

The transfer of NASA technolgy to rehabilitative applications of artificial limbs is studied. Human factors engineering activities range from orthotic manipulators to tiny dc motors and transducers to detect and transmit voluntary control signals. It is found that bicarbon implant devices are suitable for medical equipment and artificial limbs because of their biological compatibility with human body fluids and tissues

Zirconia in dental prosthetics: a literature review

A large portion of the global human population carries a type of medical implant. Dental implants are an important part of this category, and the crowns they support are vital for satisfying the patients' needs both functionally and aesthetically. Materials science pertaining to dental crowns is a driver of their development, and currently zirconium oxide (zirconia) is a promising non-metal alternative, exhibiting biocompatibility and excellent mechanical and aesthetic properties. This review aims to collate a selection of the extensive testing and research that has been performed and evaluated on a variety of zirconia-based ceramics, as there are many commercial brands developing blank and powdered samples for refinement into structurally sound dental prosthetics. Significant advancements regarding manufacturing technologies for zirconia-based ceramics are also currently in progress. Methodologies and conditions for uniaxial and isostatic pressing of zirconia powder are reviewed, as are the benefits of emerging CAD/CAM technologies. Several knowledge gaps were identified based on this review, primarily that different sintering conditions and methodologies, such as two-step sintering, should be investigated experimentally. Preliminary studies using alternative methods show promising results, and further trialling would help to ensure that the mechanical, aesthetic and ageing properties of the final product are enhanced and optimised

Fracture strength test of digitally produced ceramic-filled and unfilled dental resin restorations via 3d printing : an in vitro study

Purpose of this study was to investigate the mechanical efficiency of 3D-printed permanent and provisional implant cemented fixed bridges produced via CAD/CAM technology using an interim and a permanent ceramic filled hybrid material. Two groups with t

Comparative analysis of 3d digitization systems in the field of dental prosthetics

Amongst the modern engineering technologies which have found broad application in the field of dentistry, one of the most widely used is the 3D digitization. This paper deals with the application of 3D digitization systems in the field of dental prosthetics, and attempt to contribute in this field through comparative analysis of this kind of systems. Special attention is focused on extra oral 3D digitization systems and among them on non specialized dental 3D digitization systems. Beside the general overview and analysis of nine different systems, this paper presents experimental results of comparative accuracy analysis of two high-end 3D digitization systems - Atos II Triple Scan and Zeiss Metrotom 1500. Investigation was based on CAD inspection technique and included 3D and 2D cross sectional analysis. Results related to 3D analysis show that the majority of deviations are in positive direction, concentrated around 0,025 mm. Results of 2D analysis implicate the conclusion that the accuracy of the analysed systems is dependent on surface shape as well as on the model position during the process of 3D digitization

Comparative assessment of periodontal tissue condition during prosthetics with different types of inserts for aesthetic crowns

The advantages of the restoration of chewing teeth with ceramic inlays and composite materials are determined by the favorable physical and mechanical properties of modern ceramics with zero water absorption, optimal coefficient of thermal expansion, low thermal conductivity, biological compatibility and chemical stability in the oral cavity.. It is ceramics that is considered the most chemically inert material, and even the components - wear products that appear during abrasion do not cause allergic or toxic reactions in the oral cavity or inflammation of the marginal gums. The aim of the study was to assess the state of the periodontal tissues of teeth restored with different types of inlay core and, thus, to predict the development of pathological processes in the tissues surrounding the restored root. The conducted clinical and laboratory studies showed the significant advantages of the method of manufacturing a hip insert made of ceramics developed by us. Thus, according to the results of a comparative study of the dynamics of the level of glycogen in the periodontal tissues of the roots of teeth restored under aesthetic crowns with the use of root tabs, it is obvious that the use of ceramic tabs during prosthetics with ceramic crowns does not cause inflammatory processes in the periodontal tissues, but after traumatic exposure by preparation and preparation of the tooth before prosthetics, recover quite quickly to the level of the indicator at the healthy gingival margin

Analiza mehaničkih svojstava F75 Co-Cr legure za primjenu kod selektivnog laserskog topljenja (SLT) izrade djelomičnih zubnih proteza

The presented work discusses the applicability of the selective laser melting technique (SLM) in manufacture of removable partial denture (RPD) frameworks with the emphasis on material properties. The paper presents initial results of a conducted test of the mechanical properties of the F75 Co-Cr dental alloy used with selective laser melting.Dana istraživanja se odnose na primjenljivost tehnike selektivnog laserskog topljenja (SLT) u proizvodnji djelomičnih zubnih proteza, pri čemu je posebna pažnja usmjerena na svojstva materijala. Rad prikazuje inicijalne rezultate sprovedenog testiranja mehaničkih svojstva F75 Co-Cr dentalne legure za primjenu kod selektivnog laserskog topljenja

3D Printing of Dental Prostheses: Current and Emerging Applications

Revolutionary fabrication technologies such as three-dimensional (3D) printing to develop dental structures are expected to replace traditional methods due to their ability to establish constructs with the required mechanical properties and detailed structures. Three-dimensional printing, as an additive manufacturing approach, has the potential to rapidly fabricate complex dental prostheses by employing a bottom-up strategy in a layer-by-layer fashion. This new technology allows dentists to extend their degree of freedom in selecting, creating, and performing the required treatments. Three-dimensional printing has been narrowly employed in the fabrication of various kinds of prostheses and implants. There is still an on-demand production procedure that offers a reasonable method with superior efficiency to engineer multifaceted dental constructs. This review article aims to cover the most recent applications of 3D printing techniques in the manufacturing of dental prosthetics. More specifically, after describing various 3D printing techniques and their advantages/disadvantages, the applications of 3D printing in dental prostheses are elaborated in various examples in the literature. Different 3D printing techniques have the capability to use different materials, including thermoplastic polymers, ceramics, and metals with distinctive suitability for dental applications, which are discussed in this article. The relevant limitations and challenges that currently limit the efficacy of 3D printing in this field are also reviewed. This review article has employed five major scientific databases, including Google Scholar, PubMed, ScienceDirect, Web of Science, and Scopus, with appropriate keywords to find the most relevant literature in the subject of dental prostheses 3D printing

Fem and Von Mises analysis of OSSTEM ® dental implant structural components: evaluation of different direction dynamic loads

Abstract PURPOSE: The objective of this investigation is to study prosthodontics and internal components resistance to the masticatory stress and considering different force directions by using Finite Element Method analysis (FEM). The structural materials of the components are usually Titanium alloy grade 4 or 5 and thus, guarantee the integration of the fixture in the bone due to the osteointegration phenomena. Even if the long-term dental implant survival rate is easy to be obtained and confirmed by numerous researches, the related clinical success, due to the alteration of the mechanical and prosthodontics components is still controversial. METHODS: By applying engineering systems of investigations like FEM and Von Mises analyses, it has been investigated how dental implant material was held against the masticatory strength during the dynamic masticatory cycles. A three-dimensional system involved fixture, abutment and the connection screws, which were created and analyzed. The elastic features of the materials used in the study were taken from recent literature data. RESULTS: Data revealed a different response for both types of devices, although implant neck and dental abutment showed better results for all conditions of loading while the abutment screw represented aweak point of the system. CONCLUSION: The data of this virtual model showed all the features of different prosthetic retention systems under the masticatory load. Clinicians should find better prosthetic balance in order to better distribute the stress over the component and to guarantee patients' clinical long-term results