Experimental Study on Mechanical Properties of Different Resins Used in Oral Environments.

Background and Objectives: Acrylic resins remain the materials of choice for removable prosthesis due to their indisputable qualities. The continuous evolution in the field of dental materials offers practitioners today a multitude of therapeutic options. With the development of digital technologies, including both subtractive and additive methods, workflow has been considerably reduced and the precision of prosthetic devices has increased. The superiority of prostheses made by digital methods compared to conventional prostheses is much debated in the literature. Our study's objective was to compare the mechanical and surface properties of three types of resins used in conventional, subtractive, and additive technologies and to determine the optimal material and the most appropriate technology to obtain removable dentures with the highest mechanical longevity over time. Materials and Methods: For the mechanical tests, 90 samples were fabricated using the conventional method (heat curing), CAD/CAM milling, and 3D printing technology. The samples were analyzed for hardness, roughness, and tensile tests, and the data were statistically compared using Stata 16.1 software (StataCorp, College Station, TX, USA). A finite element method was used to show the behavior of the experimental samples in terms of the crack shape and its direction of propagation. For this assessment the materials had to be designed inside simulation software that has similar mechanical properties to those used for obtaining specimens for tensile tests. Results: The results of this study suggested that CAD/CAM milled samples showed superior surface characteristics and mechanical properties, comparable with conventional heat-cured resin samples. The propagation direction predicted by the finite element analysis (FEA) software was similar to that observed in a real-life specimen subjected to a tensile test. Conclusions: Removable dentures made from heat-cured resins remain a clinically acceptable option due to their surface quality, mechanical properties, and affordability. Three-dimensional printing technology can be successfully used as a provisional or emergency therapeutic solution. CAD/CAM milled resins exhibit the best mechanical properties with great surface finishes compared to the other two processing methods.

An Interdisciplinary Study Regarding the Characteristics of Dental Resins Used for Temporary Bridges.

Background and Objectives: The surface condition of the materials that are used for temporary prostheses influences their microbial colonization, with a direct impact on the oral tissues. This study aims at a comparative analysis of three types of resins for temporary bridges using conventional and digital technologies. The attention was focused on the analysis of the surface characteristics and mechanical strength of these materials. Materials and Methods: The surface condition was assessed for three distinct materials both before and after polishing- heat-curing resin Superpont C + B (SpofaDental, Jicin, Czech Republic) used unconventional technology, Zotion dental milling polymethyl methacrylate (PMMA) block (Zotion, Chongqing, China) for provisional crowns/bridges used in digital subtractive technologies and Freeprint Temp (Detax GmbH & Co. KG, Ettlingen, Germany) resin for temporary crowns and bridges that are used in 3D printing technologies. The two-way ANOVA analysis indicated that polishing leads to a statistically significant increase in roughness coefficients for all the three resins that were tested (p < 0.001). While the highest roughness coefficients were displayed in the 3D cured sample, the largest decrease was reported by the milled sample Results: The results revealed that surface roughness was significantly influenced by both the type of resin that was used (p < 0.001) and the treatment that was induced by finishing and polishing (p < 0.001). Similar p-values were obtained for each of the three resins. Conclusions: The results demonstrated a significant optimization of the surfaces after finishing and polishing and statistically significant differences between the surface parameters and the mechanical properties of the samples. The low values of the roughness and the acceptable values of the mechanical resistance for the conventional samples indicate these materials for the long-term temporary bridge's realization, allowing the correct restoration of the functions and the rehabilitation at the oral level.

The Impact of the Storage Conditions and Type of Clearomizers on the Increase of Heavy Metal Levels in Electronic Cigarette Liquids Retailed in Romania.

The growing popularity of electronic cigarettes has raised several public health concerns, including the risks associated with heavy metals exposure via e-liquids and vapors. The purpose of this study was to determine, using atomic absorption spectrometry, the concentrations of Pb, Ni, Zn, and Co in some commercially available e-liquid samples from Romania immediately after purchase and after storage in clearomizers. Lead and zinc were found in all investigated samples before storage. The initial concentrations of Pb ranged from 0.13 to 0.26 mg L-1, while Zn concentrations were between 0.04 and 0.07 mg L-1. Traces of nickel appeared in all investigated e-liquids before storage but in very small amounts (0.01-0.02 mg L-1). Co was below the detection limits. We investigated the influence of the storage period (1, 3, and 5 days), storage temperature (22 °C and 40 °C), and type of clearomizer. In most cases, the temperature rise and storage period increase were associated with higher concentrations of heavy metals. This confirms that storage conditions can affect metal transfer and suggests that the temperature of storage is another parameter that can influence this phenomenon.

Experimental EDX analysis of different periodontal splinting systems.

Physiological/normal tooth mobility may be defined as the slight displacement of the clinical crown of a tooth, which is allowed by the resilience of an intact and healthy periodontium, under the application of a moderate force. The factors influencing the success and longevity of dental splinting are the type of material used for the splint, the type of composite resin, the number and location of the dental units included for splinting (maxillary or mandibular arch). In periodontology, the term 'splint' is defined as the joining of two or more teeth into a rigid unit through restorations or fixed or removable devices. The purpose of using periodontal splints for tooth immobilization is to provide a period of rest in the areas where the healing process has begun and to allow normal functioning there where the tissues alone would not be able to withstand occlusal forces. The aim of the present study was to evaluate comparatively, by means of energy dispersive electron spectrometry (EDX), the chemical composition in the case of in vitro samples that structurally reproduce direct periodontal immobilization systems using fiberglass strips and fluid composite resins. The differences in the chemical composition of the investigated materials can influence their physiochemical properties, but also their biological and toxicological reliability. Elements such as C, O, Al, Si and Ba were identified as common elements among the resins tested in the present study. The only difference in terms of the component elements was found in the case of the fluid composite Clearfil Majesty ES Flow, which, apart from the elements mentioned, also presented Co in its structure.

Role of adjunctive therapy with subantimicrobial doses of doxycycline in glycemic control (HbA1c) in patients with diabetes and endo-periodontal lesions to prevent sinus complications.

The present study aimed to analyze local and regional changes in regards to odontogenic sinusitis in subjects with endo-periodontal lesions and diabetes mellitus and to investigate the effect on the level of glycemic control (glycated hemoglobin) that could be generated by adjunctive therapy with subantimicrobial doses of doxycycline. This study was performed on 51 subjects with diabetes who were divided into two therapeutic groups: 31 patients with diabetes (the study group) who underwent conventional endo-periodontal therapy and subantimicrobial doses of doxycycline and 20 patients with diabetes who followed only conventional endo-periodontal therapy (the control group). Patients underwent endodontic and periodontal clinical examination, with retro-dental-alveolar radiographs and CBCT examinations. For each patient, glycated hemoglobin A1c (HbA1c) was determined. This evaluation was performed at the beginning of the study, as well as 3, 6 and 12 months after baseline. A significant percentage of patients, both in the study group and in the control group, showed radiological signs of odontogenic sinusitis, totaling 29 patients (56.86%). Periodontal parameters revealed lower levels in patients who underwent the regimen which consisted of subantimicrobial doses of doxycycline; these results were maintained over the study period. Moreover, we demonstrated significantly reduced glycated hemoglobin levels throughout the study (12 months) in the doxycycline-treated group. This fact has far-reaching effects in the sphere of loco-regional complications as well, and the risk of odontogenic sinusitis can be significantly reduced.

Periodontal effects of two innovative oral rinsing substances in oncologic patients.

Chemotherapy often presents side effects, including oral adverse effects that may interfere with the completion of the oncology treatment, threatening the outcome of the treatment and significantly affecting the quality of life of the patient. The aim of the present study was to evaluate two antiseptic, antimicrobial and antifungal substances that may be used in order to achieve improved oral hygiene and to lower the prevalence of side effects during chemotherapy. Patients were randomly divided into three groups: Placebo, oral rinse with cetrimide and mouth coating with a pharmacy-made compound (nystatin, neomycin and metronidazole). Their oral hygiene and periodontal parameters were determined at baseline and 14 days of use. It was revealed that the most effective clinical results were achieved in the group that used cetrimide mouth rinse that highlighted the best improvements of parameter values, whereas the control and coating-using group did not obtain statistically significant improvements. Cetrimide oral rinse was demonstrated to be an efficient adjunct method in achieving better oral hygiene and improved periodontal parameters in chemotherapy patients. The present study offers an alternative to the commonly used compounds that may present unwanted side effects in patients during chemotherapy, it promotes the importance of good oral hygiene in the prevention of chemotherapy-induced oral adverse effects and improves the quality of life of the patient.