This study aimed to assess the influence of different cross-sectional area on the cyclic fatigue fracture of Ni-Ti rotary files using a fatigue tester incorporating cyclical axial movement. Six brands of Ni-Ti rotary files (ISO 30 size with .04 taper) of 10 each were tested: Alpha system (KOMET), HeroShaper (MicroMega), K3 (SybronEndo), Mtwo (VDW), NRT (Mani), and ProFile (Dentsply). A fatigue-tester (Denbotix) was designed to allow cyclic tension and compressive stress on the tip of the instrument. Each file was mounted on a torque controlled motor (Aseptico) using a 1:20 reduction contra-angle and was rotated at 300 rpm with a continuous, 6 mm axial oscillating motion inside an artificial steel canal. The canal had a 60degrees angle and a 5 mm radius of curvature. Instrument fracture was visually detected and the time until fracture was recorded by a digital stop watch. The data were analyzed statistically. Fractographic analysis of all fractured surfaces was performed to determine the fracture modes using a scanning electron microscope. Cross-sectional area at 3 mm from the tip of 3 unused Ni-Ti instruments for each group was calculated using Image-Pro Plus (Imagej 1.34n, NIH). Results showed that NRT and ProFile had significantly longer time to fracture compared to the other groups (p < .05). The cross-sectional area was not significantly associated with fatigue resistance. Fractographycally, all fractured surfaces demonstrated a combination of ductile and brittle fracture. In conclusion, there was no significant relationship between fatigue resistance and the cross-sectional area of Ni-Ti instruments under experimental conditions.
Electrons ; Fatigue ; Fractures, Stress ; Nickel ; Radius ; Steel ; Titanium ; Torque

OBJECTIVES: Although sleep problem is a common complaint in stroke survivors, there is paucity of studies on quality of sleep in old patients with stroke. The purpose of this study was to investigate the clinical characteristics associated with quality of sleep in old patients with stroke. METHODS: A comprehensive clinical and psychiatric assessments was performed in 30 patients who were admitted in rehabilitation department. Quality of sleep was evaluated with the Pittsburgh sleep quality index (PSQI). Other rating scales such as Modified Barthel Index, Korean mini mental state examination, Hamilton rating scale for anxiety, and Hamilton rating scale for depression were also performed to evaluate the clinical characteristics. RESULTS: Thirteen patients (43%) were 'poor sleeper' defined as a global PSQI score >5. In the partial correlation test, poor sleeper group were significantly associated with anxiety (r=0.69, p<0.01) and depression (r=0.76, p<0.01). In the multivariate logistic regression analysis, depression symptoms (OR=1.51, p=0.01) were only significant predictor of 'poor sleep' compared with other factors including age, sex, stroke type, stoke location, stroke site, past medical history, anxiety, and cognitive function. CONCLUSION: The results may suggest that it is important to assess depression when old patients with stroke show decreased quality of sleep. Further following studies will be needed for finding relation with other clinical factors.
Aged ; Anxiety ; Depression ; Humans ; Logistic Models ; Stroke ; Survivors ; Weights and Measures

This clinical study evaluated the whitening effect and safety of polymer based-pen type BlancTis Forte (NIBEC) containing 8.3% carbamide peroxide. Twenty volunteers used the BlancTis Forte whitening agent for 2 hours twice a day for 4 weeks. As a control, Whitening Effect Pen (LG) containing 3% hydrogen peroxide was used by 20 volunteers using the same protocol. The change in shade (DeltaE*, color difference) was measured using Shadepilot(TM) (DeguDent) before, during, and after bleaching (2 weeks, 4 weeks, and post-bleaching 4 weeks). A clinical examination for any side effects (tooth hypersensitivity or soft tissue complications) was also performed at each check-up. The following results were obtained. 1. Both the experimental and control groups displayed a noticeable change in shade (DeltaE) of over 2. No significant differences were found between the two groups (p > 0.05), implying that the two agents have a similar whitening effect. 2. The whitening effect was mainly due to changes in a and b values rather than in L value (brightness). The experimental group showed a significantly higher change in b value, thus yellow shade, than the control (p < 0.05). 3. None of the participants complained of tooth hypersensitivity or soft tissue complications, confirming the safety of both whitening agents.
Bleaching Agents ; Hydrogen Peroxide ; Hypersensitivity ; Peroxides ; Polymers ; Tooth ; Urea

OBJECTIVES: This clinical study evaluated the effect of light activation on the whitening efficacy and safety of in-office bleaching system containing 15% hydrogen peroxide gel. MATERIALS AND METHODS: Thirty-three volunteers were randomly treated with (n = 17, experimental group) or without light activation (n = 16, control group), using Zoom2 white gel (15% H2O2, Discus Dental) for a total treatment time of 45 min. Visual and instrumental color measurements were obtained using Vitapan Classical shade guide and Shadepilot (DeguDent) at screening test, after bleaching, and 1 month and 3 month after bleaching. Data were analyzed using t-test, repeated measure ANOVA, and chi-squared test. RESULTS: Zoom2 white gel produced significant shade changes in both experimental and control group when pre-treatment shade was compared with that after bleaching. However, shade difference between two groups was not statistically significant (p > 0.05). Tooth shade relapse was not detected at 3 months after bleaching. The incidence of transient tooth sensitivity was 39.4%, with being no differences between two groups. CONCLUSIONS: The application of light activation with Zoom2 white gel system neither achieved additional whitening effects nor showed more detrimental influences.
Humans ; Hydrogen ; Hydrogen Peroxide ; Hypersensitivity ; Incidence ; Light ; Mass Screening ; Recurrence ; Tooth ; Tooth Bleaching

Differentiated thyroid cancer demonstrates a wide range of clinical presentations, from very indolent cases to those with an aggressive prognosis. Therefore, diagnosing and treating each cancer appropriately based on its risk status is important. The Korean Thyroid Association (KTA) has provided and amended the clinical guidelines for thyroid cancer management since 2007. The main changes in this revised 2024 guideline include 1) individualization of surgical extent according to pathological tests and clinical findings, 2) application of active surveillance in low-risk papillary thyroid microcarcinoma, 3) indications for minimally invasive surgery, 4) adoption of World Health Organization pathological diagnostic criteria and definition of terminology in Korean, 5) update on literature evidence of recurrence risk for initial risk stratification, 6) addition of the role of molecular testing, 7) addition of definition of initial risk stratification and targeting thyroid stimulating hormone (TSH) concentrations according to ongoing risk stratification (ORS), 8) addition of treatment of perioperative hypoparathyroidism, 9) update on systemic chemotherapy, and 10) addition of treatment for pediatric patients with thyroid cancer.

The time domain entombment of bacteria by intratubular mineralization following orthograde canal obturation with mineral trioxide aggregate (MTA) was studied by scanning electron microscopy (SEM). Single-rooted human premolars (n=60) were instrumented to an apical size #50/0.06 using ProFile and treated as follows: Group 1 (n=10) was filled with phosphate buffered saline (PBS); Group 2 (n=10) was incubated with Enterococcus faecalis for 3 weeks, and then filled with PBS; Group 3 (n=20) was obturated orthograde with a paste of OrthoMTA (BioMTA, Seoul, Korea) and PBS; and Group 4 (n=20) was incubated with E. faecalis for 3 weeks and then obturated with OrthoMTA-PBS paste. Following their treatments, the coronal openings were sealed with PBS-soaked cotton and intermediate restorative material (IRM), and the roots were then stored in PBS for 1, 2, 4, 8 or 16 weeks. After each incubation period, the roots were split and their dentin/MTA interfaces examined in both longitudinal and horizontal directions by SEM. There appeared to be an increase in intratubular mineralization over time in the OrthoMTA-filled roots (Groups 3 and 4). Furthermore, there was a gradual entombment of bacteria within the dentinal tubules in the E. faecalis inoculated MTA-filled roots (Group 4). Therefore, the orthograde obturation of root canals with OrthoMTA mixed with PBS may create a favorable environment for bacterial entombment by intratubular mineralization.
Aluminum Compounds ; therapeutic use ; Calcification, Physiologic ; physiology ; Calcium Compounds ; therapeutic use ; Crystallization ; Dental Pulp Cavity ; microbiology ; Dentin ; microbiology ; Drug Combinations ; Enterococcus faecalis ; ultrastructure ; Humans ; Methylmethacrylates ; therapeutic use ; Microscopy, Electron, Scanning ; Oxides ; therapeutic use ; Root Canal Filling Materials ; therapeutic use ; Root Canal Obturation ; methods ; Root Canal Preparation ; instrumentation ; Silicates ; therapeutic use ; Time Factors ; Zinc Oxide-Eugenol Cement ; therapeutic use