Bacterial leakage of provisional restorative materials used in endodontics.

OBJECTIVE: To test the bacterial sealing ability of commonly used provisional endodontic restorative materials. METHOD AND MATERIALS: This study investigated Cavit (3M ESPE), Ketac (3M ESPE), DuoTemp (Coltane/Whaledent), and a combination technique using Ketac and Cavit. One hundred molars were randomly selected and then mounted in an apparatus that isolated the crown portion of the tooth. Provisional restorative materials were placed in an open access following manufacturer guidelines. Streptococcus mutans was applied to the samples, and results were tabulated over the course of 4 weeks. RESULTS: Cavit and DuoTemp performed the best, and Ketac performed the worst. After 14 days, however, all materials leaked in over half of the samples. CONCLUSION: No material can be recommended as superior in providing a reliable seal after 14 days.

Effects of stimulation duration on electrogustometric thresholds.

The ability to detect low electrical currents presented to the lingual surface is widely used to assess taste function in humans. Despite this fact, the influence of stimulus duration on electrical taste thresholds is not well established. In this study, we evaluated the effects of current duration (0.5, 1.0, and 1.5 s) on electrogustometric detection thresholds for two regions of the anterior tongue in 24 college students. Anodal stimulation was produced using a stainless steel 12.5-mm(2) electrode, and thresholds were determined using a single-staircase procedure. A non-monotonic function for the threshold values was observed for both tongue regions across the stimulus durations, with the 1.0-s duration stimulus resulting in a lower threshold value (i.e., higher sensitivity) than either the 0.5- or 1.5-s durations, which did not differ in magnitude from one another. These data suggest that stimulus-duration-related enhancement of lingual detection threshold sensitivity to electric currents disappears at some point after 1 s.