Time-based lateral hygroscopic expansion of a water-expandable endodontic obturation point

This study compared the time-based lateral expansion of two sizes and two batches of water-expandable obturation points (CPoint, EndoTechnologies, LLC) and a similar-sized gutta-percha point (control) at various distances from the point apex: 5, 10, and 15mm.

Two batches of sizes 25 and 40 (0.06 taper) CPoints and a single lot of size 40 (0.06 taper) gutta-percha were tested (N=5). Points were fixed to the bottom of a Petri dish, and digital images of each point location were obtained under 50× magnification, which also captured a calibrated linear scale reticule. After imaging each dry cone location, 10mL of water was added, and images were obtained at various time points: 20 and 40min, 1, 2, 3, 4, 5, 6, 7, 8, and 24h. Between measurements, dishes were stored at 37°C. Side-to-side dimension of each point was determined using imaging software

No significant differences (p>0.05) in lateral dimension at each tip distance between batches of similar-sized CPoint samples were found (2-tailed unpaired Student's t-test). Changes in CPoint dimension were significantly higher (p<0.05) for both sizes at each tip distance after 20min of water immersion (one-factor repeated-measures ANOVA; Tukey test). Gutta-percha did not significantly change from the dry value during water immersion (p>0.05).

When exposed to water, the lateral expansion of a new hydrophilic endodontic obturation point significantly increases in dimension within 20min, whereas a conventional gutta-percha point does not.