A randomised, double-blind, placebo-controlled, comparative study of topical skin analgesics and the anxiety and discomfort associated with venous cannulation.

OBJECTIVES: To compare the effect of topical skin anaesthetic agents on the discomfort and anxiety associated with venous cannulation. DESIGN: Randomised, double-blind, placebo-controlled, within subject, volunteer trial. METHODS: 20 healthy volunteers underwent venous cannulation on three separate occasions having received topical skin application of either 4% amethocaine gel (Ametop), 5% eutectic mixture of lidocaine and prilocaine (EMLA) or E45 cream (placebo). Visual analogue and verbal rating scales were used to assess pain and anxiety associated with the venous cannulation, and anticipated anxiety for future cannulation, under each drug condition. RESULTS: Subjects were aged 22-53 years (mean 32.8 years). The mean visual analogue scores (VAS) for discomfort were found to be significantly lower (p< 0.001) with Ametop (VAS = 18mm) and EMLA (VAS = 29mm) compared with the control (VAS = 38mm). There was a positive correlation (R2 = 72%, p<0.001) between discomfort and the predicted anxiety if cannulation was to be repeated with the same cream. With the placebo a positive correlation (R2 = 19.8%, p = 0.05) was found between the level of anxiety before cannulation and the level of discomfort recorded. CONCLUSIONS: Ametop and EMLA topical anaesthetic agents produce effective skin analgesia for venous cannulation. The use of topical analgesia can reduce perceived anxiety about future cannulation procedures. This has application in the management of anxious patients undergoing intravenous sedation, suggesting that topical analgesia prior to venous cannulation may significantly aid anxiolysis.

In vitro radiographic representation of the extent of voids within obturated root canals.

The aim of this study was to determine whether radiographs provide an accurate representation of the degree of root canal obturation following a cold lateral condensation technique. A total of 40 extracted single-rooted lower premolar teeth were prepared using either a standardized step-back technique or an ultrasonic device by one of two operators. The four groups each of 10 teeth were obturated using lateral condensation by a third operator. To assess apical leakage the obturated teeth were coated with nail varnish to within 2 mm of the apex and immersed in methylene blue for 48 h. The teeth were then radiographed in bucco-lingual and mesio-distal planes prior to subsequent sectioning in a bucco-lingual plane. Sections and radiographs were analysed using an image analysis apparatus to determine the proportion of root canal occupied by gutta-percha, void and/or sealer. Mean percentages of void calculated from the bucco-lingual radiographs, mesiodistal radiographs and tooth sections were 4.14%, 5.98% and 4.98%, respectively. Statistical analysis showed no significant differences between the radiographic views and the tooth sections (P > 0.05). Both planes of radiograph accurately represented the proportion of void when compared with the tooth section.