Evaluation of the influence of apical sizes on the apical sealing ability of the modified continuous wave technique / 대한치과보존학회지

This study examined the influence of the apical sizes on the sealing ability of a root canal filling. Thirty-six single rooted teeth with a single canal were divided into 3 groups (n = 12) and instrumented with either the Profile(R) or LightSpeed(R) system to achieve three different apical sizes (master apical file [MAF] of #25, #40, or #60). The teeth were filled with gutta percha using a modified continuous wave technique. The level of microleakage was determined by immersing ten teeth from each group into India ink for 1 week followed by clearing with nitric acid, ethyl-alcohol, and methylsalicylate. The microleakage was measured using vernier calipers. The data was analyzed statistically using Kruskal-Wallis one-way ANOVA and a Student-Newman-Keuls Method. Two teeth from each group were sectioned horizontally at 1, 2, 3 and 4 mm from the apex in order to observe a cross section. The apical size was significantly (p < .05) influenced the level of microleakage. In the Student-Newman-Deuls Method, MAF sizes of #25 and #40; and MAF sizes of #25 and #60, respectively showed a statistically significant difference. There was no significant difference between #40 and #60. In most cross sections, oval-shaped canals were observed, and the irregularity of the internal surface increased with decreasing apical size. There was also an increase in the area of recess, which is the area where the canal space is not filled with either gutta-percha or sealer. When the root canals are filled using a modified continuous wave technique, canal filling with more consistent and predictable outcome may be expected as the apical preparation size is increased.

Selective detection of viable Enterococcus faecalis using propidium monoazide in combination with real-time PCR / 대한치과보존학회지

Polymerase chain reaction (PCR) can detect bacteria more rapidly than conventional plate counting. However DNA-based assays cannot distinguish between viable and dead cells due to persistence of DNA after cells have lost their vitality. Recently, propidium monoazide (PMA) treatment has been introduced. The purpose of this study is to evaluate the applicability of the PMA treatment and real-time PCR method for cell counting in comparison with plate counting and to evaluate the antibacterial efficacy of 2% CHX on E. faecalis using PMA treatment in combination with real-time PCR. Firstly, to elucidate the relationship between the proportion of viable cells and the real-time PCR signals after PMA treatment, mixtures with different ratios of viable and dead cells were used. Secondly, relative difference of viable cells using PMA treatment in combination with real-time PCR was compared with CFU by plate counting. Lastly, antibacterial efficacy of 2% CHX on E. faecalis was measured using PMA treatment in combination with real-time PCR. The results were as follows : 1. Ct value increased with decreasing proportion of viable E. faecalis. 2. There was correlation between viable cells measured by real-time PCR after PMA treatment and CFU by plate counting until Optical density (OD) value remains under 1.0. However, viable cells measured by real-time PCR after PMA treatment have decreased at 1.5 of OD value while CFU kept increasing. 3. Relative difference of viable E. faecalis decreased more after longer application of 2% CHX.

Metric Study of Upper Airway and Trachea in Nomal Korean Adults uing Fiberoptic Bronchoscopy: Study of endotracheal tube fixation positioning in adults / 대한마취과학회지

BACKGROUND: Neck flexion risks endobroncheal intubation when the tracheal tube is not in the proper position. So accurate knowledge of upper airway length is required to prevent malpositioning of endotracheal tubes. Therefore we evaluated the length of various portions of upper airway in Korean adults (n=500) who had no abnormality of upper airway. METHODS: Five hundred patients, composed of 198 males and 302 females who underwent elective surgery, were included in this study. After endotracheal tube was placed under general anesthesia, we measured the distance from tube machine-end to upper incisor (value 1), from tube machine-end to inferior margin of cricothyroid membrane (value 2), and from tube machine-end to carina (value 3) by means of fiberoptic bronchoscopy. RESULTS: The mean length between upper incisor and inferior margin of cricothyroid membrane (value 2 - value 1) was 12.7 cm in males and 11.6 cm in females, while the mean length between superior margin of cricoid cartilage and carina (value 3 - value 2) was 12.9 cm in males and 11.3 cm in females. So the mean length between upper incisor and the mid portion of trachea was nearly 19.6 cm in males and 17.7 cm in females. CONCLUSIONS: We believe that, based on the findings in this study, the safety length for endotracheal tube fixation is 20 cm in Korean adult males and 18 cm in Korean adult females.