ELECTRICAL RESISTANCE OF DENTAL LUTING CEMENTS INVESTIGATED BY IMPEDANCE METHODOLOGY RELATED TO THEIR POROSITIES AND SOLUBILITY

The electrical resistance property of dental cement is one of important physical properties. Most previous studies aimed to investigate the mechanical properties, solubility and especially bonding property. Few studied on physical property of electrical insulation of dental cement. Therefore, investigating the electrical resistance of dental luting cements and the relation among the electrical resistance, the porosities and the solubility of dental luting cements are interesting to study. Five types of dental luting cements were used including Hybond, Fuji II, Rely-X Unicem, Rely-XTM U-100 and Superbond C&B. The electrical resistance of dental luting cements was then investigated by the impedance methodology. The porosities of all specimens were observed by micro CT scan before impedance test. The solubility of luting cement was calculated from weight of specimens before and after impedance test. All data was statistically analyzed with independent t-test and one-way ANOVA at p-value of 0.05. It was found that the electrical resistance of resin luting cements including both types of Rely-X and Superbond C&B is higher than 2000 ×106 Ω. However, the electrical resistance of zinc phosphate cements were higher than glass ionomer cements, 0.017×106 and 0.003×106, respectively. Additionally, the mean porosity of Superbond C&B was significantly higher than the other four types of luting cements. Both zinc phosphate and glass ionomer cements showed the solubility but were not significant. This study also found no correlation among the electrical resistance, the porosities and the solubility regardless of dental luting cements. Within the limitation of this study, it can be concluded that electrical resistance of dental luting cement is related to the chemical composition and setting reaction but do not relate to amount of porosity and degree of solubility. The electrical resistance related to the pores inside the dental luting cements.