Eugenol uses, from clove oil by Ray Sahelian, M.D.

Eugenol is a clear to pale yellow oily liquid extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, and bay leaf. Eugenol has a pleasant, spicy, clove-like aroma.

Eugenol as analgesic in dentistry
Eugenol, a natural congener of capsaicin, is a routine analgesic agent in dentistry. Eugenol is a major component of root canal sealers and retrograde filling materials. Zinc-oxide powder mixed with eugenol or cariofillorum oil and sterilized cotton is frequently used in dental practice as surgical bandage for eliminating or dry socket. Osteonecrosis of alveolar bone caused by free eugenol is rare but a possible complication.

Eugenol inhibits the antimicrobial functions of neutrophils.
J Endod. 2008.
Eugenol containing restorative materials are commonly used for vital pulp therapy. A well-regulated host defense response is pivotal for the success of vital pulp therapy. The present study was to assess the effects of eugenol on the antimicrobial functions of polymorphonuclear leukocytes (neutrophils). Treatment for 30 minutes did not significantly affect the viability of neutrophils. However, preincubation of neutrophils with eugenol abolished their bactericidal activity against oral pathogens Streptococcus mutans and Actinobacillus actinomycetemcomitans. In addition, through the suppression of the extracellular release of myeloperoxidase and the intracellular production of reactive oxygen species, eugenol at sufficient concentrations impaired the activation of neutrophils by cytochalasin B and fMet-Leu-Phe. These results suggested that the antimicrobial functions of neutrophils were interfered by eugenol, and the inhibitory effects of eugenol were not due to direct killing of neutrophils.