pH influences the volumetric change of calcium silicate- and epoxy resin-based root canal sealers: An ex vivo micro-CT study

Volumetric changes in root canal sealers in ex vivo and a novel animal model approach

AIM

This study aimed to evaluate the volumetric change of root canal sealers through micro-computed tomographic analysis using a novel in vivo model and to compare the results with those obtained using an ex vivo test.

METHODOLOGY

Eighteen single-rooted teeth were cut to 5 mm length from the root apex. The root canals were uniformly enlarged and filled with EndoSequence BC Sealer or AH Plus Jet root canal sealers. Samples were stored at 37°C and 95% relative humidity for 24 h and then scanned with a micro-CT device. Twelve samples (n = 6 for each sealer) were implanted in the subcutaneous tissue of Wistar rats, while six samples (n = 3 for each sealer) were immersed in 20 mL of phosphate-buffered saline (PBS) at 37°C at neutral pH. After 7 and 30 days, teeth were removed from subcutaneous tissue or PBS and rescanned. Statistical analysis of volume changes was performed using Shapiro-Wilk's test and independent t-test (p < .05).

RESULTS

AH Plus Jet had smaller volume changes (-2.2 to +0.77%) than EndoSequence BC Sealer (-2.0 to +4.0%) (p < .05), in the two tested models. The volume of the root canal sealers decreased over time (p < .05), in vivo. AH Plus Jet results varied between the in vivo and ex vivo results (p < .05), while EndoSequence BC Sealer presented similar volume losses for both experimental models (p > .05).

CONCLUSION

EndoSequence BC Sealer lost more volume than AH Plus Jet. The experimental conditions influenced the volumetric change of AH Plus Jet but not the EndoSequence BC Sealer. The ex vivo model should be further explored as a methodological alternative to assess the volumetric changes of root canal sealers without causing harm to animals.

Volume and power of expansion of novel polyurethane-based sealers

INTRODUCTION

Shrinkage and lack of interfacial adaptation between endodontic sealers and root canal walls may jeopardize the root canal treatment outcome. This study aimed to evaluate the volume and power of expansion (and the relationship between the two) of three novel root canal sealers (polyurethane expandable sealer (PES), zeolite + PES (ZPES), and elastomeric polyurethane sealer (EPS)) in comparison with an epoxy-resin based sealer (AH Plus) and a calcium silicate-based sealer (EndoSequence BC).

METHODS

This study utilized 36 cylinders (30 plastic graduated cylinders for volume of expansion and 6 steel cylinders for power of expansion) (4x10mm) filled with PES, ZPES, EPS, AH Plus, EndoSequence BC, or water (n=5/group). The plastic graduated cylinders were inserted inside a customized Linear Swell Meter (LSM) apparatus to measure the percentage of volumetric expansion. The steel cylinders were placed inside an LSM apparatus mounted onto a universal testing machine to measure the maximum pressure in psi. Specimens were tested for 72 hours for both volume and power of expansion tests. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, Post Hoc Tukey, and Pearson correlation tests (p<0.05).

RESULTS

The volume of expansion of PES, ZPES, and EPS was significantly higher than in AH Plus and EndoSequence BC (p<0.05). For the power of expansion, no significant differences were found between the root-filling materials (p>0.05). No correlation was seen between the volume and power of expansion (p>0.05).

CONCLUSION

Although polyurethane-based sealers showed a significantly higher volume of expansion compared to AH Plus and EndoSequence BC, their power of expansion did not increase significantly.