Correspondence Address:
Dr. Sekar Mahalaxmi
Department of Conservative Dentistry and Endodontics, SRM Dental College, Ramapuram, SRM Institute of Science and Technology, Ramapuram Campus, Chennai, Tamil Nadu
India

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Dear Editor,

We read with interest the recent article titled “Histological evaluation of the synergistic effect of chitosan and mineral trioxide aggregate (MTA) on mechanically exposed dental pulp following pulp capping in dogs' teeth” by Emara et al. published in your esteemed journal.[1] The study highlighted the histological appearance of dentin bridge formation following direct pulp capping using chitosan-incorporated MTA in a dog model. The authors' efforts are highly commendable; however, we would like to put forth our observations pertaining to this interesting study.

Freshly mixed hydrated MTA has an initial pH of 10.2 which gradually rises to 12.5.[2] However, chitosan exhibits limited water solubility, especially above pH 6.5 and it usually requires an acidic medium for its dissolution.[3] Therefore, it would have been highly appreciated if the investigators had thrown light on the solubility of chitosan in the alkaline liquid of MTA as well as about the technical aspects of its preparation methodology. Further, the microstructural and pH changes due to the addition of chitosan to MTA have not been elucidated. The authors have also not adequately justified the use of 10 wt% concentration of chitosan employed in this study. Literature evidence reveals the effectiveness of lower concentrations of chitosan (0.625% to 2.5% w/v) in portland cement for dentin regeneration in vitro.[4] Hence, the optimization of chitosan-modified MTA using physicochemical and biological characterization studies will add further value to the current investigation.

However, another point to be considered is the bond strength between the restorative materials and pulp capping agent which is quite crucial for a successful treatment outcome. It has been earlier reported that overlaying of calcium silicate-based pulp capping agents with GIC/RMGIC as employed in the present investigation, results in adhesive failure due to low shear bond strength.[5] Low etching capability of polyacrylic acid and water adsorption from the setting MTA cement during the hydration process are the prime reasons for the adhesive failure.[5] This raises concern about the seal of the final restoration over the 60 days' time period. In addition, the authors could have employed a split-mouth design in this dog model analysis for better standardization. Hence, all the aforementioned observations can be potentially considered by the authors before clinical translation of the chitosan-modified MTA for pulp capping applications.

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Conflicts of interest

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