Effects of Removal Conditions on Mercury Amount Remaining in the Oral Cavity and inside Drainage System after Removing Dental Amalgams

Radiofrequency-Induced Heating of Amalgam Restorations and Dental Implants during 1.5T Magnetic Resonance Imaging

Objectives: This study aimed to evaluate radiofrequency-induced heating of different amalgam restorations and dental implants during 1.5T magnetic resonance imaging (MRI). Materials and Methods: Standardized class I cavities (5 mm long, 3 mm wide, and 3 mm deep) were prepared on the occlusal surface of 45 extracted human third molars. The samples were restored by three different types of amalgam including Cinalux amalgam (non-gamma-2, spherical), GS-80 (non-gamma-2, admix), and GK-110 amalgam (non-gamma-2, admix in silver). As a separate intervention group (G4), five titanium mini drive-lock implants with 2mm diameter and 10mm length were also selected and mounted to the base of the Eppendorf tube with 3mm of the implants extending above the mounting putty. The box containing the specimens was placed parallel to the long axis of the standard head and neck coil of the MRI device (64MHz radio-frequency energy with 25kW amplifier, 1.5T). Temperature fluctuations of the metallic materials in each group were monitored during MRI scans using a calibrated thermometer. One-way ANOVA was used to compare temperature changes among the amalgam groups (P<0.05). Results: Temperature elevations ranged from 0.21°C to 0.70°C in amalgam restorations and from 0.35 to 0.47°C in dental implants. The temperature changes among the three amalgam agents were not statistically significant. Conclusion: According to our findings, the radiofrequency-induced heating of amalgam restorations and dental implants during MRI examination can be considered within acceptable ranges. Therefore, amalgam restorations and dental implants can be categorized as "MR safe" in terms of radiofrequency-induced heating during 1.5 T MRI.

Awareness of Students and Dentists on Sustainability Issues, Safety of Use and Disposal of Dental Amalgam

Among the pillars of sustainability in health care units is environmental protection. Although an EU-wide dental amalgam phase-out legislation exists, quantities of this material are still to be found in the market, dental offices or in the mouths of patients. The purpose of this study is to record the views of dentists and dental students in Greece regarding the use and safety of dental amalgam for people and the environment as well as their attitudes towards its restriction and disposal.

MATERIALS AND METHODS

Two different questionnaires, through Google forms, were filled by each group. Descriptive statistics were used to describe the variables. The chi-square test or the chi-square test with Yates correction was used to examine potential differences per group (p-value = 0.05). Overall, 564 people participated in this study; 462 (81.9%) dentists (N1) and 102 (18.1%) dental students (N2).

RESULTS

Both groups agreed that they no longer use dental amalgam often. Dentists (39.8%) and students (36.4%) consider amalgam to have a moderate burden on the environment. This answer differed significantly per year of profession and year of undergraduate studies, respectively, with dentists from 6-25 years in the profession and 4th-year students, being the least aware on the environmental footprint of dental amalgam. Further, professionals (70%) and students (60%) believe that dental amalgam has a hazardous impact on patient's health, at all or to a small extent. For staff health, dentists reported at a moderate degree dangerous impact (32.9%) while students (36.4%), respectively. The impact on patients and staff health, were found to differ significantly per region of practicing dentistry for both groups. Finally, there were suggestions made from both groups about the necessity of information sharing on amalgam and mercury safety and the impact on the environment at the level of professional organizations.

CONCLUSIONS

Students, younger dentists and those living in non-urban regions seem to be more sensitive to the environmental impact of amalgam use, disposal, and health of people. Environmental issues should be addressed thoroughly by professional organizations, enhancing relevant activities for all people involved.

Structural Conformation Comparison of Different Clear Aligner Systems: An In Vitro Study

The aim of this study was to evaluate the structural conformations of three clear aligner systems, Eon^®, SureSmile^®, and Clarity^®, and compare them with the most commonly used system, Invisalign^®. Clear aligner samples from Invisalign^®, Eon^®, SureSmile^®, and Clarity^® were cut into 5 × 5 mm squares and exposed to artificial saliva for 2 weeks. The specimens were then subjected to a Vickers hardness test by applying three separate indentations with a 25 gf load for 15 s. Hardness was calculated using the following formula: Vickers hardness number = 1.854 (F/D2). Fourier transform infrared spectroscopy (FTIR) analysis was performed, with a diamond hemisphere and infrared beam being allowed to pass through each specimen. A mid-infrared range from 4000 to 375 cm⁻¹ was recorded. The samples were also evaluated using scanning electron microscopy (SEM) combined with energy-dispersive X-ray microanalysis spectroscopy at different magnifications. No statistically significant differences were observed between the included systems with regard to hardness. All systems showed a polyurethane-based material, as illustrated by the FTIR analysis. Some structural variations were noted in the Invisalign^® system, which had a more homogeneous architecture. Statistically significant differences in the carbon weights were found among the systems. The four systems presented comparable hardness levels. Mild molecular composition differences were found, but all systems had the similarity of being composed of a polyurethane-based material. Carbon and oxygen were the main elements, as they were located in all studied clear aligners. The SEM analysis revealed that Invisalign^® had a smoother surface than the other three systems. All included clear aligners had similar characteristics with minimal differences, providing a wide variety of options for clinical orthodontic treatment according to patients’ demands.