Influence of different sized files on the accuracy of two electronic apex locators.

The aim of this study was to evaluate the impact of different file sizes on the accuracy of two electronic apex locators (EALs). Thirty extracted human single-rooted permanent mandibular incisors were used. A #10 K-file was inserted in the root canal until its end could be observed (using a light microscope) through the apical foramen. One millimetre was subtracted to establish working length (WL). Electronic readings were performed using MiniApex Locator or Root ZX II, from #10 K-file to #130 K-file. Statistical analysis was performed by two-way anova and Tukey test (P ≤ 0.05). From #60 to #130 K-file, observed differences were noted between the values obtained with both EALs and WL (P ≤ 0.05). The MiniApex Locator showed increased means when measurements were made with #50 to #70 and with #120 (P = 0.008) and #130 (P = 0.005) K-files. File sizes influenced the accuracy of EALs - the greater the instrumentation size, the higher mean differences compared to WL.

Efficacy of the NaviTip FX irrigation needle in removing calcium hydroxide from root canal.

OBJECTIVE: To evaluate the effectiveness of the NaviTip FX, brush-covered irrigation needle, in removing calcium hydroxide from the root canal. STUDY DESIGN: Thirty single-rooted teeth were randomly divided into three groups: A - irrigation with a hypodermic needle inserted as far as possible without binding and activation with #30 K-type file; B - Irrigation with a hypodermic needle without activation; C - irrigation with NaviTip FX needle. Sodium hypoclorite 1% was used in irrigation. The root canals were examined trough scanning electron microscopy. Calcium hydroxide removal was recorded at 1, 5, and 10mm from the working length (WL) and the data were analysed using one-way ANOVA test (p<0.05). RESULTS: NaviTip FX and hypodermic needle activated with #30K-type file showed lower score at 10 and 5mm with no significant difference between them. Comparison within groups did not show significant differences. All groups showed significantly better smear layer removal at 5 and 10 mm from the WL. CONCLUSION: The apical third (1mm) of the root canal was found to be the most critical site for Ca(OH)2 removal. Key words:Calcium hydroxide, irrigation, scanning electron microscope, NaviTip FX.

Influence of embedding media on the assessment of electronic apex locators.

Third-generation electronic apex locators for root canal length determination are very reliable and are not subject to interference from the contents of the canals. This study compared the effectiveness of different embedding media for in vitro assessment of electronic apex locators. The tooth lengths of 30 extracted human mandibular central incisors were measured by introducing a size 15 K-file fitted with a silicone stop into the canal until its tip appeared through the apical foramen; the distance between the tip and stop was measured. The teeth were placed in cylindrical polyethylene tubes filled with different embedding media (1% agar, gelatin, alginate, saline, and flower sponge soaked in saline), and electronic reading was performed with the Root ZX device. Data were statistically assessed by the analysis of variance (ANOVA) and Tukey tests at a significance level of 5%. Despite the lack of statistically significant difference among the media, the flower sponge was the only medium in which the file surpassed the apex in some measurements.

Evaluation of apical cavity preparation with a new type of ultrasonic diamond tip.

This study evaluated the time, occurrence of fracture, and quality of apical cavity preparation with three different ultrasonic diamond tips: Satelec, Trinity, and a new type, CVD (chemical vapor deposition), using scanning electron microscopy (SEM) analysis. Thirty human single-rooted premolars were selected, submitted to apicectomy, and prepared with ultrasonic tips; impressions were then obtained. The presence of fractures was evaluated on the impressions, and the quality of preparation was evaluated by SEM analysis of teeth and scoring by two examiners. The group prepared with the CVD tips exhibited the shorter preparation time and did not present fractures. There was no statistically significant difference in the quality of preparation for the three tips. The three brands of ultrasonic tips produced adequate grinding without altering the morphology of the apical foramen.