Influence of calcium-hydroxide removal techniques on accuracy of RootZX

To evaluate the effect of calcium hydroxide (Ca(OH)₂)  removal techniques  on the accuracy of Root ZX in enlarged root canals and compare the efficiency of these techniques for the removal of Ca(OH)₂from root canals.

Methods:

90 freshly extracted human maxillary incisors were prepared with ProTaper rotary system to an apical size F3. During the preparation, root canals were irrigated with 2mL of 2.5% NaOCl solution between each file and then filled with injectable Ca(OH)₂ paste. Specimens were stored for 1 week at 37°C in 100% relative humidity. 6 teeth assigned randomly as control group (G) and six groups (n=14) arranged as follows: G1: only irrigation with 10mL 0,9% saline, G2: same manner as G1 and instrumentation with master apical file (MAF), G3: 10mL 17% EDTA, G4: G3 and MAF, G5: 10mL 5,25% NaOCl, G6: G5 and MAF. All specimens were mounted in an experimental apparatus for measuring root lengths via Root-ZX. Electronic measurements compared with actual canal lengths that were determined at beginning of study by inserting #10 file until the tip was visualized (12.8× magnification) just within the apical foramina. After all roots sectioned longitudinally along the length of the instrumented canals, each half was examined with a stereomicroscope at 500× magnification and photographed digitally.  Residual Ca(OH)₂ in root canals were measured via COMEF 4.3 software. The measurements of residual Ca(OH)₂was analyzed with oneway ANOVA with post-hoc LSD test, and lengths measurements was analyzed with Kruskal-Wallis with post-hoc Dunn’s test.

Results:

Significantly less residual material was obtained in G4 and G6 than the other groups (p< 0.05). Root ZX was highly accurate in G4 and G6.

Conclusions:

None of the techniques removed the Ca(OH)₂ dressing completely. Remaining Ca(OH)₂ influenced the accuracy of RootZX.