Surface quality of yttria-stabilized tetragonal zirconia polycrystal in CAD/CAM milling, sintering, polishing and sandblasting processes

This paper studied the surface quality (damage, morphology, and phase transformation) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in CAD/CAM milling, and subsequent polishing, sintering and sandblasting processes applied in dental restorations. X-ray diffraction and scanning electron microscopy (SEM) were used to scan all processed surfaces to determine phase transformations and analyse surface damage morphology, respectively. The average surface roughness (Rₐ) and maximum roughness (R(z)) for all processed surfaces were measured using desk-top SEM-assisted morphology analytical software. X-ray diffraction patterns prove the sintering-induced monoclinic-tetragonal phase transformation while the sandblasting-induced phase transformation was not detected. The CAD/CAM milling of pre-sintered Y-TZP produced very rough surfaces with extensive fractures and cracks. Simply polishing or sintering of milled pre-sintered surfaces did not significantly improve their surface roughness (ANOVA, p>0.05). Neither sintering-polishing of the milled surfaces could effectively improve the surface roughness (ANOVA, p>0.05). The best surface morphology was produced in the milling-polishing-sintering process, achieving Rₐ=0.21±0.03 µm and R(z)=1.73±0.04 µm, which meets the threshold for bacterial retention. Sandblasting of intaglios with smaller abrasives was recommended as larger abrasive produced visible surface defects. This study provides technical insights into process selection for Y-TZP to achieve the improved restorative quality

Validity assessment of the laparoscopic radical nephrectomy module of the LapVision virtual reality simulator

Background: Virtual reality simulators allow trainees to perform repeated practice and provide objective dexterity metrics regarding their performance, which means that virtual reality-based surgical training is becoming a vital part of initial learning of basic laparoscopic surgical skills. However, its educational role in learning advanced procedures remains undetermined. We evaluated the validity of the laparoscopic radical nephrectomy module of the LapVision virtual reality simulator. Methods: Urologists, medical students, and a junior resident voluntarily participated in the present study, and they performed training with a laparoscopic left radical nephrectomy module. For construct validation, dexterity metrics calculated in the simulator and the mean score of Global Operative Assessment of Laparoscopic Skills evaluated by 2 experts' video review were compared according to the certification of Japanese Endoscopic Surgical Skill Qualification or previous surgical experience. Results: Ten experts (>= 50 laparoscopic surgeries), 9 intermediates (11-49), and 14 novices (0-10) voluntarily participated in the present study. Regarding the construct validity, there was a significant difference in the total number of errors, blood loss, and Global Operative Assessment of Laparoscopic Skills score among the groups for both the Endoscopic Surgical Skill Qualification status and previous surgical experience. Conclusion: The present study demonstrated good construct validity for the LapVision nephrectomy module. Furthermore, global skill assessment was possible by experts' reviews, which indicates the usefulness of the virtual reality procedural module as a skill assessment tool. Virtual reality-based procedural simulation has marked potential to become a vital part of integrated laparoscopic training programs. (C) 2019 The Authors. Published by Elsevier Inc

CHANGES IN ACTIVITIES OF DAILY LIVING,PHYSICAL FITNESS, AND DEPRESSIVE SYMPTOMS AFTER SIX-MONTH PERIODIC WELL-ROUNDED EXERCISE PROGRAMS FOR OLDER ADULTS LIVING IN NURSING HOMES OR SPECIAL NURSING FACILITIES

A 6-month, twice weekly, well-rounded exercise program (47 sessions in total) comprised of a combination of aerobic, resistance and lexibility training was provided for institutionalized older adults aged 60 to 93. We analyzed the data of 18 older adults who could stand and had attended more than 10% of the classes (mean participation rate: 54%) to examine changes in activities of daily living (ADL), physical fitness tests and depressive moods. The mean (± standard deviation, range) age of the participants was 71.3 (±15.6, 60–93) in men and 85.9 (±5.8, 72–93) in women. Significant improvement in ADL of the hand manipulation domain and borderline significant improvement in ADL of the mobility domain were observed (McNemar test p=0.011 and 0.072, respectively). A 6-minute walk distance increased significantly from 151.6 m to 236.6 m (p=0.01, paired t-test), and the result of the Soda Pop test, which tests hand-eye coordination, also improved significantly from 35.2 sec to 25.3 sec (p=0.01, paired t-test). These findings suggest that such a program could be effective in improving the ADL and physical fitness of the elderly

Motion analysis for better understanding of psychomotor skills in laparoscopy : objective assessment-based simulation training using animal organs

Background Our aim was to characterize the motions of multiple laparoscopic surgical instruments among participants with different levels of surgical experience in a series of wet-lab training drills, in which participants need to perform a range of surgical procedures including grasping tissue, tissue traction and dissection, applying a Hem-o-lok clip, and suturing/knotting, and digitize the level of surgical competency. Methods Participants performed tissue dissection around the aorta, dividing encountered vessels after applying a Hem-o-lok (Task 1), and renal parenchymal closure (Task 2: suturing, Task 3: suturing and knot-tying), using swine cadaveric organs placed in a box trainer under a motion capture (Mocap) system. Motion-related metrics were compared according to participants' level of surgical experience (experts: 50 <= laparoscopic surgeries, intermediates: 10-49, novices: 0-9), using the Kruskal-Wallis test, and significant metrics were subjected to principal component analysis (PCA). Results A total of 15 experts, 12 intermediates, and 18 novices participated in the training. In Task 1, a shorter path length and faster velocity/acceleration/jerk were observed using both scissors and a Hem-o-lok applier in the experts, and Hem-o-lok-related metrics markedly contributed to the 1st principal component on PCA analysis, followed by scissors-related metrics. Higher-level skills including a shorter path length and faster velocity were observed in both hands of the experts also in tasks 2 and 3. Sub-analysis showed that, in experts with 100 <= cases, scissors moved more frequently in the "close zone (0 <= to < 2.0 cm from aorta)" than those with 50-99 cases. Conclusion Our novel Mocap system recognized significant differences in several metrics in multiple instruments according to the level of surgical experience. "Applying a Hem-o-lok clip on a pedicle" strongly reflected the level of surgical experience, and zone-metrics may be a promising tool to assess surgical expertise. Our next challenge is to give completely objective feedback to trainees on-site in the wet-lab