From an assessment of multiple chelators, clodronate has potential for use in continuous chelation

Abstract

Aim To identify chelators which when mixed with sodium hypochlorite (NaOCl) are stable, exhibiting minimal loss of free available chlorine (FAC) over 80 min and to further investigate potential mixtures by assessing FAC over 18 h and the capacity to remove smear layer. Methodology 0.25 mol L−1 EDTA (10%), 0.25 mol L−1 EGTA (egtazic acid), 0.25 mol L−1 CDTA (cyclohexanediaminetetraacetic acid), 0.25 mol L−1 DTPA (pentetic acid), 0.5 mol L−1 ATMP (aminotri(methylene phosphonic acid)) and 1 mol L−1 HPAA, (hydroxyphosphonoacetic acid), all at alkaline pH, were mixed equally with 5% NaOCl. 0.5 mol L−1 alkaline clodronate and 0.5 mol L−1 Na4etidronate (15%) were mixed equally with 10% NaOCl. For all mixtures, the pH and temperature were measured over 80 min and additionally for the clodronate mixture over 18 h. Iodometric titration was used to measure the FAC of all mixtures except for HPAA. The following were compared with respect to their ability to remove smear layer: 1 mol L−1 clodronate + 10% NaOCl, 0.5 mol L−1 clodronate + 10% NaOCl, 1 mol L−1 etidronate + 10% NaOCl, 0.5 mol L−1 clodronate + 10% NaOCl and the sequences 5% NaOCl/17% EDTA/5% NaOCl and 5% NaOCl/17% EDTA. The area fraction occupied by open dentinal tubules as a percentage of the total area (% AF) from scanning electron microscopy micrographs was calculated using Image J. The results were statistically analysed with alpha set at 0.05. Results Compared to its control, the mixture 0.5 mol L−1 clodronate + 10% NaOCl lost no FAC over 18 h (P > 0.05). The FAC of 0.25 mol L−1 CDTA mixed with 5% NaOCl fell to 96%, 92%, 75% and 4.9% at 20, 40, 60 and 80 min, respectively. Temperature rises were observed in all cases except in the etidronate and clodronate mixtures. Only in the clodronate mixture did the pH remain above pH 12 for the whole experiment. Although smear layer was removed, the % AF in 1 mol L−1 clodronate + 10% NaOCl, 0.5 mol L−1 clodronate + 10% NaOCl, 1 mol L−1 etidronate + 10% NaOCl was less than for 0.5 mol L−1 etidronate + 10% NaOCl and 5% NaOCl/17% EDTA/5% NaOCl and 5% NaOCl/17% EDTA. Conclusion Alkaline 0.5 mol L−1 clodronate mixed equally with 10% NaOCl has potential for use in continuous chelation, based on this assessment of stability and smear layer removal. Further research is needed to establish its efficacy and safety.

Novel Approaches to Detect and Treat Biofilms within the Root Canals of Teeth: A Review

“…This is not possible using EDTA since it interacts chemically with NaOCl, consuming the free available chlorine, and rendering the mixture inactive [48]. Recent research has shown the value of certain non-nitrogen-containing bisphosphonates, such as clodronate, for use in continuous chelation, since they do not react with NaOCl, and give stable mixtures with excellent smear layer removal capabilities as well as powerful antimicrobial actions [49,50]. The continuous chelation approach may be able to reduce time and complexity, as well as improve the quality of debridement of the canal by its more potent actions on biofilms and smear layer.…”

Continuous Chelation in Endodontics with a Focus on the Novel Chelator Clodronate

“…With regard to concentration, in the present study, the final concentration of clodronate in the mixture was 0.52 M. This is over twice the concentration examined previously, which was 0.25 M (Wright et al 2020a). The doubling in chelator concentration in the current experiment explains why changes in FAC occurred at 3 hours at room temperature, compared to 18 hours in the prior study.…”

“…The chelator solution used was 1. (Wright et al 2020a). The NaOCl stock solution and a 10% dilution were stored in the dark at 2-4 o C.…”

“…The FAC was determined with iodometric titration, utilising a burette, as previously described (Wright et al 2020a 60, 120 and 180 minutes, while for solutions stored at 2-4 o C, the time points for measurements were: 1 minute, 1 day, 3 days, 1 week, 2 weeks, 6 weeks and 3 months.…”

“…Recently, clodronate has been identified as having potential for use in continuous chelation (Wright et al 2020a). The mixture 0.25 M (7.3%) clodronate-5% NaOCl has the capacity to remove smear layer, with no loss of FAC when kept for 18 hours at room temperature (Wright et al 2020a). No studies exist however on the effect on the FAC of clodronate and NaOCl mixtures at temperatures other than room temperature.…”