Indirect Restorative Polymeric Dental Materials

The current chapter, entitled “Indirect restorative polymeric dental materials,” is dedicated to one class of dental materials with wide indications in dental medicine. The chapter is an overview of polymeric resin composites dedicated to indirect restauration currently used and latest avail resin composite and polymers in dentistry. This chapter includes chemical composition, indications, light-curing mechanism and physical and mechanical properties of indirect conventional and new polymeric materials. Important aspects about resin composites are related to clinical and physical properties such as light-curing, aesthetics, wear rates and biocompatibility. The accuracy and longevity of indirect composite restorations depend on choosing the right material according to clinical requirements, material’s properties, and behaviour in the oral cavity and clinical indications. The chemical composition of resin composite, curing mechanism and advantages of these materials are presented in Introduction. The second section is dedicated to structure and composition of indirect polymers, indirect resin composites, first and second generation of indirect resin composites and their indications. Section 3 describes the structure and composition of high-performance hybrid polymers, hybrid ceramic and high-performance polymers, and poly ether ketone ketone dedicated to different processing technologies

Dental Anatomy and Morphology of Permanent Teeth

The present chapter is proposing a detailed and illustrated description of dental morphology of permanent dentition. The main topics are related to nomenclature, age of emergence, a description of teeth’s tissues (pulp, dentin, enamel, and cement), and morphology of all permanent teeth. The main focus of this chapter is the description of individualized morphology and specific variations of each permanent tooth. The goal of all treatment phases in dental medicine is to restore the function, integrity, and morphology of the oral cavity, and all these achievements are reached through deep knowledge of dental morphology. Cavities are restored with direct dental materials, which need to be carved according to the natural shape, outlines, occlusal and proximal contacts of teeth’s morphology, reproducing also the shade and translucencies of natural teeth. The same goal dominates the prosthodontic field. It is well known in dental medicine that shape, size, and position assure the optimal function and preserve the self-maintenance of dental arches and dento-maxillary system. For esthetic, function, and self-preservation, all dental treatment fields have to first consider the dental morphology

Study Regarding some Physico-chemical Properties of Composite Resins for Direct Restorations

Aim: This study investigated the physicochemical properties i.e. water sorption (Wsp) and solubility (Wsl) of one experimental composite in comparison with four commercially available materialsused for direct restorations. Material and Methods: Disc-shaped specimens of each material were prepared and investigated according to the ISO standard 4049:2000. Results: The experimentalcomposite had similar water sorption values with the trade-mark composites after 1 day storage. Significant differences regarding Wsp were found after 7 days and respectively 1 month of immersion (p<0.05). Similarities between the experimental composite and the trade-mark materials were observed regarding Wsl. Conclusion: The Wsp and Wsl values of the experimental material as well as of the trade-mark composites are in accordance with ISO standard 4049:2000, that is Wsp <40 μg/ mm3 and Wsl <7.5 μg/mm3

Original Research. Photoacoustic Microscopy in Dental Medicine

Introduction: Photoacoustic microscopy, also known as optoacoustic imaging, is a comparatively new method of investigation in dental medicine, which uses a laser-generated ultrasound (short laser pulses) to achieve images for interpretation. Photoacoustic microscopy can be used in a broad spectrum, from detecting tooth decay at its earliest stages to dental anatomy analysis. Material and methods: The energy emitted by the photoacoustic pulse is moderately absorbed by the target and exchanged into heat, leading to a local transitory temperature upsurge. The tension propagates and grows as ultrasonic waves, distinguished by the ultrasonic transducers which are planted apart from the tissue. The photoacoustic microscope has a tunable dye laser which passes through a condensing lens, an objective and ultimately an ultrasonic transducer attached to an acoustic lens to capture and receive information about the scanned probe from a sample moved on the X, Y dimensions. Results: The precise anatomy of layered concentric structures can be clearly observed in photoacoustic microscopy. The image value of the inner layer can be higher, indicating strong optical absorption, while the image value of the outer layer is lower, indicating weaker optical absorption. Meanwhile, the inner layer has the exact same size as the dentin structure and the outer layer has the exact same size as the enamel structure in this cross-section. Conclusions: The photoacoustic microscope (all-optical) comes out to be a future and promising tool for detecting early-stage caries and lesions on the surface of the teeth, where micro-leakage occurs at the interface of tooth restoration, and also the anatomy of dental tissues

MECHANICAL AND FRACTOGRAPHIC ASSESSMENT OF DIFFERENT TYPES OF ENDODONTIC POST SYSTEMS USED IN THE RESTORATION OF DEVITALIZED TEETH

Aim of the study The resistance to functional and parafunctional stresses of devitalized teeth is multifactorial, but the choice of a specific endodontic post system influences the restoration’s longevity. This primary ex-vivo study aims to evaluate the compressive strength of three different non-metallic post systems and to analyze the appearance of fracture surfaces (fractography) using optical microscopy and alongside statistical analysis that validates their behavior. Material and methods For this study, three groups of non-metallic post systems were considered as follows: glass fiber-reinforced photopolymerized resin, pressed ceramic, and pressed ceramic on glass fiber. The sample size has a length of 0.8mm and an average diameter of 0.2mm. Subsequently, the samples were embedded in self-polymerizing resin to be secured in the workspace of the Zwick Roell 5kN testing machine that works at loading speed of 2 mm/min. The fractographic analysis of the obtained surfaces were performed with the Optika SLX3 microscope and C-B16 camera, at magnifications of 20, 50, and 90X. Results The data obtained from the mechanical tests were statistically processed and the results showed significant differences regarding the compressive strength of non-metallic post systems made from different materials and different technologies. Conclusions The group containing posts made from pressed ceramic on glass fiber exhibited higher resistance to applied compressive forces

THE ADVANTAGES OF THE IMPLEMENTATION OF DIGITAL FLOW IN THE WORKING TIME MANAGEMENT OF DENTAL PROSTHESES RESTORATIONS

The aim of the study is to perform a comparison between conventional impression versus intraoral and extraoral scanning, plaster models compared to virtual and printed models, in terms of working time and fidelity. Material and method: The study evaluates two groups of practitioners: 30 dentists and 30 dental technicians, regarding registration and reproduction of the prosthetic field. The time required to perform the operations was evaluated in relation to variables that can influence the final results. Conventional impressions were monophasic and biphasic. In the digital flow, an intraoral scanner (Medit, i700) and a laboratory scanner (Medit T310) were used. Also, a printing machine (Elegoo Saturn) was used to print the models. Results and discussions: The average time allocated for conventional impressions is between 8min and 20sec and 25min and 40sec. The scanning time varied between 5 min 30 sec and 12 min 40 sec. Conclusions: The digital impression requires less working time compared to the conventional one, the latter cannot be completely abandoned, at least in terms of mobile prostheses. The fidelity of the prosthodontic field reproduction influences the adaptation of the restorations