Analysis of Fetor ex Ore by Gas Chromatography

Abstract

The sulphur compounds in fetor ex ore were assayed by gas chromatography equipped with FID detector. For further identification of suspected compounds, FPD detector and gas chromatographymass spectrometer (GC-MS) were employed. The oral air samples were collected into a gas-tight syringe through closed lips or the exhaled air were concentrated on a glass beads collector coated with mercury chloride.
The subjects of this experiments were chosen from the patients by the olfactory panel composed of dentists with good sense of smell. There were clear cut differences between the gas chromatogram obtained from normal persons and patients.
The gas chromatogram from patients was affected by toothbrushing or Flagyl (Metronidazole) to approach the pattern of that from normal persons.
The detailed results were as follows:
1. Using a glass column (3mm×2m) packed with chromosorb 104 (no coating), two peaks with short retention time were increased in oral air samples from patients, but not coincided with the standard sulphur compounds.
2. Using a glass column (3mm×3m) packed with 25% TCEP on chromosorb G, seven peaks were observed by FID, of which the peak No. 5 and No. 7 clearly predominated in the patient group.
3. The peak No. 5 was identified as dimethyl sulfide based on the retention time.
4. By use of FPD detector (with S filter), hydrogen sulfide [H₂S], methyl mercatan [CH₃SH], ethyl mercaptan [C₂H₅SH] and dimethyl sulfide [(CH₃)₂S] were identified in oral air samples from patients, while only the peak of H₂S was found in the normal person group.
5. The peak No. 5 (estimated to be dimethyl sulfide) and No. 7 (unknown) was further identified by GC-MS.
The peak No. 7 was estimated to be a substance with moleculer weight 281, containing no sulphur.
6. By toothbrushing, the level of peaks was reduced or disappeared, and fetor ex ore was also reduced by the sensory estimation of the olfactory panel.
7. It is well established that an antitrichomonas drug, Metronidozole, is very effective to cure fetor ex ore by oral administration. The pattern of gas chromatogram was also improved to that of normal persons in almost all cases.
8. The gas chromatography and GC-MS method appeared to be very promising in clinical practice for the objective diagnosis of fetor ex ore and also for criteria for the effectiveness of oral hygiene practice or medical treatments.