RESUMO
Polyetheretherketone (PEEK) has become popular for removable partial denture (RPD) frameworks but reports on their clinical follow-up and repair are lacking. Two defective PEEK-framework RPDs were repaired with computer-aided design and manufacturing technology, saving costs and time and simplifying the treatment process.
RESUMO
OBJECTIVES: This work aimed to study the effects of loupes and microscopes on a dental technician's working posture during practical operation from ergonomic aspects. The technician's working postures under the conditions of the naked eye, loupes, and microscopes were compared. The practical value of loupes and microscopes was assessed based on the evaluation index of working posture from ergonomic aspects. METHODS: Three dental technicians who were skilled in using loupes and microscopes from West China Stomatology Technology Department of Sichuan University were involved in this prospective rando-mized controlled trial. Before the operation, cameras were installed in the sagittal position, top-view position, and dorsal position of the operation. Each technician made five porcelain veneers of the right maxillary central incisor following the standard process. A chairside computer-aided design and computer-aided manufacturing (CAD/CAM) system was used to mill and layer the ceramic block under the naked eye (A: control group), 3.5× headwear loupes (B: loupe group), and 9× desktop microscopes (C: microscope group). The working posture was recorded by videos throughout the entire process. After each operation, the investigator used OpenPose to recognize the working posture. The joint angles of the arm, elbow, wrist, neck, and trunk, as well as their corresponding rapid upper limb assessment (RULA) scores, were calcula-ted by MATLAB. The working posture was assessed from ergonomic aspects based on the joint angles, RULA scores, and operation time. Statistical analysis was performed using SPSS 26.0. RESULTS: The RULA score of upper limb joint angles showed that the angles of the arm, elbow, wrist, neck, and trunk under the naked eye were 14.93°±9.44°, 120.19°±2.99°, 23.97°±2.84°, 47.27°±5.72°, and 7.76°±2.30°, respectively. All of the joint angles were significantly different among the three groups (P<0.05). Compared with the control group, the angles of the neck and trunk in the loupe group were reduced by 29.09% and 42.53%, respectively, whereas those in the microscope group were significantly reduced by 43.99% and 87.11%, respectively. Multiple comparisons by LSD for the angles of neck and trunk revealed that the loupe group and the microscope group were significantly different from the control group (P<0.05), and they were also significantly different from each other (P<0.05). The mean RULA scores were 6.24±0.34 in the control group, 5.53±0.35 in the loupe group, and 3.31±0.19 in the microscope group. Compared with the control group, the mean RULA score in the loupe group was lower, and that in the microscope group was significantly lower. The differences between every two groups were statistically significant (P<0.05). The mean RULA score in the microscope group was significantly lower than that in the loupe group (P<0.05). The average operation times of the control group, loupe group, and microscope group were (50.69±36.78), (52.01±34.65), and (59.44±35.81) min, respectively. No significant difference was found among the three groups (P>0.05). CONCLUSIONS: Use of loupes and microscopes showed an improvement in ergonomics and working posture of dental technicians. Microscopes had a better effect in the ergonomic convenience of the technician than loupes.
RESUMO
Many patients with large-area tooth defect need cast post-core crown restoration. However, the color defect of the cast post-core will affect the final restorative result, especially that of the anterior teeth. A new technology of color masking by applying CERAMAGE polymeric porcelain to the cast metal post-core surface improves the color of a full-ceramic restoration of anterior teeth and may provide a new alternative for the aesthetic repair of anterior teeth with a large area of defective tooth.
Assuntos
Porcelana Dentária , Técnica para Retentor Intrarradicular , Cerâmica , Coroas , Estética Dentária , HumanosRESUMO
A theoretical investigation on structural and thermodynamic properties of 11-type iron-based superconductor FeSe at high pressure and high temperature was performed by employing the first-principles method based on the density functional theory. Some structural parameters of FeSe in both tetragonal and hexagonal phases are reported. According to the fourth-order Birch-Murnaghan equation of states, the transition pressure P(t) of FeSe from the PbO-type phase to the NiAs-type phase was determined. The calculated results are found to be in good agreement with the available experimental data. Based on the quasi-harmonic Debye model, the pressure and temperature dependence of the thermodynamic properties for hexagonal phase FeSe were investigated. Our theoretical calculations suggest that the pressure and temperature have significant effects on the heat capacity, vibrational internal energy, vibrational entropy, vibrational Helmholtz free energy, thermal expansion coefficient and Debye temperature. Even though few theoretical reports on the structural properties of FeSe are found in the current literature, to our knowledge, this is a novel theoretical investigation on the structural and thermodynamic properties of FeSe at high temperature. We hope that the theoretical results reported here can give more insight into the structural and thermodynamic properties of other iron-based superconductors at high temperature.