Vaporization of Formaldehyde from Root Canal Dressing using Formalin Guaiacol(FG)

Abstract

The present study aimed to obtain information on the formaldehyde vapor concentration of the surrounding air of a dental clinic during root canal dressing using Formalin Guaiacol (FG). The measurements were made at Tohoku University Hospital Dental Center, Clinical Division of Endodontics, for five days in the summer and winter of 2008. A human extracted lower first molar tooth was prepared for root canal dressing using a cotton point soaked in FG. The tooth was fixed to the headrest of a dental chair, and a total of 2 liters of surrounding air was collected in 10 minutes using an automatic gas sampling device. The collection was carried out under four treatment conditions as follows: 1) root canal dressing using FG without any suction of surrounding air (treatment 1), 2) root canal dressing with suction of surrounding air using a suction installed to the dental chair (treatment 2), 3) root canal dressing with suction of surrounding air using an extra-oral suction (Denpax®NDP-510, Denpax) (treatment 3), and 4) leaving the cotton point soaked with FG on the headrest of the dental chair (treatment 4). Preceding the treatment, surrounding air was collected as background data. The concentration of formaldehyde vapor in the collected air was later estimated by high-performance liquid chromatography. The concentration of formaldehyde vapor in the collected air was lower than the legally designated limit in Japan. There was no significant difference between background concentrations under the different treatments. However, background concentrations in the summer were significantly higher than those in winter (repeated measurement ANOVA, p<0.01). The concentrations under the four treatments were significantly different both in summer and in winter (repeated measurement ANOVA, p<0.01), and treatment 4 led to a concentration significantly higher than that under the other three treatments (Scheffe's test, p<0.01). Our results indicated that root canal dressing using FG produces formaldehyde vapor at an acceptable concentration designated by law and the use of a dental vacuum effectively reduced the formaldehyde concentrations of surrounding air in the clinic.