Endodontic sealers are crucial for obturation, and AH Plus has been a gold standard epoxy-based sealer. However, newer sealers incorporate tricalcium silicate (TCS)-based cements for their biocompatibility and setting expansion, offering an alternative to Portland cement-based materials like MTA, mitigating concerns about leaching of trace elements and aluminum. Total Fill BC sealer, a widely researched TCS-based material, contains higher levels of tricalcium and dicalcium silicate, and lower zirconium oxide, compared to the newly launched AH Plus Bioceramic sealer which contains a lower volume of tricalcium silicate and a high volume of zirconium oxide. Another new epoxy-based sealer, BJM RCS, incorporates anti-biofilm macromolecules. This study aimed to investigate, using an in vitro pull-out test, the effect of varying chemical compositions, including the addition of macromolecules to epoxy-based sealers, and changes in the main component volumes in TCS sealers, on the ability of these sealers to resist gutta-percha cone removal. This pull-out test serves as an indirect measure of sealing ability. Previous research using micro-CT analysis has shown varying degrees of gap formation between gutta-percha and sealers, highlighting the need for further investigation into the impact of sealer composition on adaptation.

The literature review highlights the importance of endodontic sealers and the existing gold standard, AH Plus. It discusses the advantages of TCS-based sealers over MTA, addressing concerns regarding trace element leaching. The review also introduces the specific characteristics of Total Fill BC and AH Plus Bioceramic, including their varying compositions of tricalcium silicate, dicalcium silicate, and zirconium oxide. Additionally, it mentions the BJM RCS sealer with its incorporated anti-biofilm macromolecules. Finally, the review establishes the in-vitro pull-out test as a valid method for assessing sealer sealing ability, citing previous studies that used similar techniques to evaluate the bond strength of different cements and sealing mechanisms. A gap in the literature was identified concerning the effects of modifying the chemical composition of these sealers on their resistance to gutta-percha cone removal.

Fifty extracted human molars with suitable distal/palatal canals were prepared to ISO size 45 using DC Taper rotary files. Canals were irrigated with NaOCl and EDTA. Teeth were divided into five groups (n=10 per group): AH Plus, BJM RCS, Total Fill BC, AH Plus Bioceramic, and a control group with gutta-percha only. Each group was obturated using a single 45 ISO gutta-percha cone with its corresponding sealer (except the control group). Two additional teeth per group were used to assess sealer setting. After 10 days, a Shimadzo Universal Testing Machine performed a pull-out test at 1 mm/min until cone removal or rupture. The maximum force was recorded for each specimen. Data analysis was performed using SPSS version 27, with one-way ANOVA and Bonferroni post-hoc tests for continuous variables and Chi-square tests for categorical variables. A blinded researcher conducted the pull-out tests. The study followed the Declaration of Helsinki and obtained Institutional Review Board approval.

The pull-out force needed to remove or rupture the gutta-percha cone was significantly higher in the AH Plus, BJM RCS, and Total Fill BC groups compared to the AH Plus Bioceramic group (p<0.001). The AH Plus group required double the force compared to the AH Plus Bioceramic group (1.87 ± 0.53 N vs. 0.93 ± 0.48 N). All cones in the AH Plus Bioceramic group were removed completely, significantly differing from other groups (p=0.01). The control group showed zero pull-out force. There was no significant difference in pull-out force between AH Plus, BJM RCS, and Total Fill BC. The number of cones completely removed versus torn also showed a significant difference between the AH Plus Bioceramic group and the others. The force needed to remove the cone by the other sealers was similar to the one needed to tear the cone but nevertheless significantly higher than the force needed by the AH Plus Bioceramic sealer.

The findings indicate that the addition of macromolecules (BioSafe) to epoxy sealer (BJM RCS) does not significantly affect its resistance to gutta-percha removal compared to standard epoxy sealer (AH Plus). The significantly lower pull-out resistance of the AH Plus Bioceramic sealer suggests that its reduced tri- and di-calcium silicate content and increased zirconium oxide negatively impact its adaptation to the gutta-percha cone. This may be due to decreased expansion ability of the sealer or increased gap formation at the interface. The complete removal of all gutta-percha cones in the AH Plus Bioceramic group further emphasizes this inferior adaptation. The variations in whether the cone was torn or completely removed may be attributed to factors such as variations in canal cross-section, patient age influencing dentin properties, and the presence of biofilm remnants. The results support that the pull-out test effectively reflects the sealer’s ability to resist gutta-percha removal.

This study demonstrates that the addition of macromolecules to epoxy-based sealers does not improve their resistance to gutta-percha cone removal. Conversely, reducing the amount of tri- and di-calcium silicate while increasing zirconium oxide in a bioceramic sealer significantly diminishes this resistance. Future research could explore the effect of other chemical modifications on sealer properties and investigate the correlation between pull-out resistance and long-term clinical outcomes. Further investigation into the gap formation at the gutta-percha-sealer interface with different sealer compositions is also warranted.

The study's limitations include the in-vitro nature of the experiment, which may not perfectly replicate the complex in-vivo conditions of the root canal. The use of extracted teeth introduces variability related to age, tooth morphology, and pre-extraction pulp conditions. The single-cone obturation technique might introduce variability in sealer layer thickness. Despite these limitations, the study provides valuable insights into the relationship between sealer composition and resistance to gutta-percha removal.