الفهرس 
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Abstract
This study was aimed to evaluate the solubility, water sorption and cytotoxicity of resin modified light cured calcium silicate pulp capping material (TheraCal) with different light curing times. This material was introduced recently to overcome many drawbacks of previous materials, as: solubility of calcium hydroxide, difficulty in manipulation and long setting of MTA.
Sixty specimens of Theracal were prepared and divided into two groups: 30 were subjected to cytotoxicity test, and 30 for solubility and water sorption testing, and each group was further divided into three sub groups according to the time of light curing: 20s,15s, and 10s curing times. The specimens were prepared in specially fabricated Teflon mold with dimensions of (8x1mm). The solubility of the material was assessed according to the American Dental Association (ADA) for water-based dental cements and International Standard Organization (ISO) no. 6876 for root canal sealing materials. After preparation, specimens were weighed five times to produce a mean using an electronic sensitive balance, and the initial dry mass M1 was recorded for each specimen, then each specimen was incubated in 10 ml distilled water at 37 C̊ for 24 hours, after that the specimens were removed from the water, blotted dry and weighed individually five times to produce the mean and a wet mass M2 was recorded, then the specimens were dried using a desiccator and weighed daily five times until reaching a constant mass (nearest 0.001g) and the final dry mass M3 was recorded (M3 was reached after 3 days of weighing).
Solubility and water sorption were assessed by gravimetric determination as a percentage weight variation (Δ%). And for cytotoxicity evaluation each specimen was extracted at a ratio of 3 cm2/mL according to the ISO 10993-12 recommendation using distilled water (DW), the samples were incubated in 0.4ml of DW in a sterile red coded blood testing tubes, to ensure a sterile condition, the elutes of all specimens were collected at 37∘C for 24 hours in an incubator. HDPSCs were isolated from extracted caries-free molars, cultured in Dulbecco’s modified Eagle’s medium (DMEM), all material extracts were sterilized using ultraviolet light, HDPSCs were co-cultured with the supplemented media and the material extract for another 24 hour. And then cell viability was assessed using mitochondrial dehydrogenase enzymatic MTT assay.
The results showed that theracal solubility was statistically significant higher at curing time 10 seconds using One-way ANOVA to compare between different tested groups followed by Tukey’s post-hoc test for pairwise comparisons, Water sorption of theracal was higher at curing time 20 and 10 seconds, and it was statistically significantly lower at curing time 15 seconds, and number of viable cells that were exposed to theracal elutes were not statistically significantly different when light curing at 20,15, and 10 seconds was performed.
Conclusions:
Under the limitations of this in vitro study, the followings were concluded:
1. Marked decrease in light curing time had a determinant effect regarding the solubility of light cured resin modified calcium silicate material.
2. There was no direct correlation between cytotoxicity of light cured resin modified calcium silicate material and the variation in light curing time.