Improvement of Biological Effects of Root-Filling Materials for Primary Teeth by Incorporating Sodium Iodide

Abstract

Therapeutic iodoform (CHI3) is commonly used as a root-filling material for primary teeth; however, the side effects of iodoform-containing materials, including early root resorption, have been reported. To overcome this problem, a water-soluble iodide (NaI)-incorporated root-filling material was developed. Calcium hydroxide, silicone oil, and NaI were incorporated in different weight proportions (30:30:X), and the resulting material was denoted DX (D5~D30), indicating the NaI content. As a control, iodoform instead of NaI was incorporated at a ratio of 30:30:30, and the material was denoted I30. The physicochemical (flow, film thickness, radiopacity, viscosity, water absorption, solubility, and ion releases) and biological (cytotoxicity, TRAP, ARS, and analysis of osteoclastic markers) properties were determined. The amount of iodine, sodium, and calcium ion releases and the pH were higher in D30 than I30, and the highest level of unknown extracted molecules was detected in I30. In the cell viability test, all groups except 100% D30 showed no cytotoxicity. In the 50% nontoxic extract, D30 showed decreased osteoclast formation compared with I30. In summary, NaI-incorporated materials showed adequate physicochemical properties and low osteoclast formation compared to their iodoform-counterpart. Thus, NaI-incorporated materials may be used as a substitute for iodoform-counterparts in root-filling materials after further (pre)clinical investigation.

Effectiveness of Sodium Iodide Root Canal Filling Pastes in Primary Teeth

“…The atomic number, density, and size of the chemicals in the root canal paste have a significant impact on how x-rays interact with matter at the atomic level [35,36]. Since sodium iodide (molecular weight 149.89 g/mol) has a lower atomic number than that of iodoform (393.732 g/mol), NaI paste showed the lowest radiopacity when compared to Vitapex® and Metapex®, which was consistent with a previous study [13]. However, there was no statistically significant difference among the groups.…”

“…However, NaI paste exhibited the highest antibacterial activity, suggesting that sodium iodide is a more effective bactericidal agent than iodoform. Although high antimicrobial activity can sometimes be associated with high cell toxicity, a study by Choi et al, found that NaI paste did not induce cell cytotoxicity, suggesting that it may be effective against bacteria within dentinal tubules without being toxic [13]. Nevertheless, this study was conducted in vitro over a short period of time, and further research is needed to validate these findings in vivo.…”

“…According to prior investigations, pastes containing iodoform exhibited a noteworthy survival rate in both human osteosarcoma cell lines and animal models [33,34]. Furthermore, it has been observed that NaI pastes display high cell viability on osteoclast precursor cells [13]. This observation suggests that both iodoform-based pastes and NaI pastes may demonstrate biocompatibility when extruded over the apex; however, additional clinical investigations are required to validate these results.…”

“…However, it has a different molecular weight of 149.89 g/mol and is watersoluble. In a previous study [13], the physicochemical properties of sodium iodide paste were compared to those of iodoform paste, which is blended in a ratio of 1 : 1 : 1 with calcium hydroxide and silicone oil. As such, this current investigation endeavors to assess the potential applicability of sodium iodide paste by examining its effectiveness in comparison to commercially available iodoform paste.…”

“…A prior research indicated that Sodium Iodide (NaI) could be used as a substitute for iodoform to reduce root resorption [13]. This conclusion was drawn based on the observation of a lower level of osteoclast differentiation in RAW 264.7 cells when exposed to NaI paste compared to iodoform based paste, as osteoclasts are responsible for resorption activity [14].…”