In vitro oral epithelium cytotoxicity and in vivo inflammatory inducing effects of anesthetic rice gel.

In vitro cytotoxicity of lidocaine hydrochloride (LH) and prilocaine hydrochloride (PH) to oral epithelial cells, isolated from tissue specimens of healthy volunteers, were evaluated. Cell vitality after treating with 1-20% anesthetic solutions for 5 and 30 min was investigated using F-actin and 4',6-diamidino-2-phenylindole staining technique and observed by fluorescence microscopy. Vitality rate of more than 90% was found in all anesthetic groups at both durations whereas no survived cell was found in a positive control group (sodium dodecyl sulfate). Lactate dehydrogenase (LDH) assay was performed to confirm the safety of both anesthetic solutions. Cell culture medium after treating with LH or PH for 5 and 30 min were collected and analyzed using commercial kits. The results showed no significant difference between the test groups and negative control group (untreated culture) with low LDH levels. In vivo inflammatory inducing effect of 5, 10, 20% LH or PH loaded rice gels was investigated in healthy volunteers. Tumor necrosis factor alpha (TNF-α) in gingival cervicular fluid was determined by ELISA technique. It was found that the expression of TNF-α was not different from the baseline. The expression of this inflammatory mediator caused by the commercial gel was higher than those of both anesthetic rice gels. It might be due to the effects of other excipients in the formulation of the commercial product. It is concluded that LH or PH possess no cytotoxicity to oral epithelium and the developed rice gel base and LH and PH rice gels do not induce inflammatory effect to oral tissues.