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

ALTERNATIVE METHODS OF REMOVING CARIOUS TISSUE

Aim of the study: This study aims to comparatively analyse two chemo-mechanical caries removers, Carisolv and BRIX3000. The study involves physico-chemical characterization of the substances followed by assessing their impact on carious lesions using extracted teeth. Materials and Methods: Carisolv, a caries removal gel, and BRIX3000, a gel from papaya protein, were used in this study. Extracted teeth with carious lesions were maintained in saline solution, treated individually with the respective substances, and examined using optical and spectroscopic techniques. Results and Discussion: FTIR spectroscopy demonstrated characteristic peaks confirming the specific compositions of BRIX3000 and Carisolv. Thermal analysis revealed the degradation behaviours of the compounds, indicating differences in thermal stability. VistaCam technology showed significant reductions in carious lesions post-treatment with both substances, with BRIX3000 exhibiting superior efficacy. Conclusion: The investigation confirmed the effectiveness of Carisolv and BRIX3000 in treating caries lesions, supporting their potential as viable treatment options. Further, BRIX3000 exhibited greater efficacy and distinct behaviour compared to Carisolv, offering insights into their impact on dental structures. However, cytotoxic effects were observed with BRIX3000, warranting further exploration into its safety profile

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

ASSESSMENT OF DENTAL CERAMIC SINTERED AT DIFFERENT TEMPERATURES

Aim of the Study: The aim of this study is to investigate the modifications that may occur in case of sintering temperature deviation for metal-ceramic crowns. Materials and Methods: For this in vitro study were made 15 metal-ceramic crowns for tooth 2.1 and were divided into 5 groups. The ceramic veneering comprised different sintering temperatures optimized for different properties: group 1 was sintered at 910 ºC as per the manufacturer’s recommendation, group 2 was sintered at 940ºC (+30 ºC), group 3 was sintered at 960ºC (+50 ºC), group 4 was sintered at 880ºC (-30 ºC), and group 5 was sintered at 860 ºC (-50 ºC). Using the EXOCAD scanner the maxillary cast was scanned to obtain the metal frameworks from Cr-Co alloy (SCHEFTNER CoCr – 30 microns). Ips InLine One ceramic shade A3 developed by Ivoclar Vivadent Inc is applied in two layers, each one sintered at the same temperature. After ceramic sintering, the shade of each group was registered with Vita Easy Shade spectrophotometer and Vitapan Classical shade guide. Results: Errors in sintering temperatures can change the ceramic’s density and mechanical properties but may also lead to colour shifts. This phenomenon occurs due to alterations in the ceramic material’s microstructure, which can impact its optical properties and, consequently, its perceived colour. Conclusions: In conclusion, our study highlights the crucial impact of sintering temperature variations on the quality and integrity of metal-ceramic dental restorations. Our findings point towards the need for further innovation and research in thermal management within dental ceramics processing to achieve restorations that are not only aesthetically pleasing but also functionally reliable and compatible with the natural dentition

THE IMPACT OF FABRICATION METHODOLOGIES ON THE FLEXURAL STRENGTH OF COMPLETE DENTURES: AN INVESTIGATION INTO TECHNOLOGICAL INFLUENCES

Aim of the study. In this study, we examined how the choice of fabrication technology impacts the flexural strength of denture bases, considering the potential long-term consequences of permanent stresses on these structures. Such stresses can eventually result in cracking, fracture, or a loss of adaptation within the prosthetic field, which undergoes dynamic changes over time. Material and methods. The flexural strength was tested on specimens made of the same material (based on thermopolymerizable PMMA), using three different technologies: the classic press packing process and traditional polymerization, the injection technology and polymerization under constant pressure and an original suction-injection process (vacuum-pressure alternation), with polymerization under continuous pressure. The actual testing of the flexural strength was carried out in collaboration with the Department of Strength of Materials within the Faculty of Civil Engineering and Architecture Timisoara. Results & Conclusions. Superior outcomes were achieved through the suction-injection method, with polymerization under sustained pressure, in comparison to injection techniques associated with polymerization under constant pressure. These results surpassed those attained through manual press packing procedures and traditional hot polymerization methods