The aim of the present study was to determine the antibacterial activities of the phenolic essential oil (EO) compounds hinokitiol, carvacrol, thymol, and menthol against oral pathogens. Aggregatibacter actinomycetemcomitans, Streptococcus mutans, Methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia. coli were used in this study. The minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), bacterial growth curves, temperature and pH stabilities, and synergistic effects of the liquid and vapor EO compounds were tested. The MIC/MBC of the EO compounds, ranging from the strongest to weakest, were hinokitiol (40–60 μg/mL/40-100 μg/mL), thymol (100–200 μg/mL/200-400 μg/mL), carvacrol (200–400 μg/mL/200-600 μg/mL), and menthol (500-more than 2500 μg/mL/1000-more than 2500 μg/mL). The antibacterial activities of the four EO phenolic compound based on the agar diffusion test and bacterial growth curves showed that the four EO phenolic compounds were stable under different temperatures for 24 h, but the thymol activity decreased when the temperature was higher than 80°C. The combination of liquid carvacrol with thymol did not show any synergistic effects. The activities of the vaporous carvacrol and thymol were inhibited by the presence of water. Continual violent shaking during culture enhanced the activity of menthol. Both liquid and vaporous hinokitiol were stable at different temperatures and pH conditions. The combination of vaporous hinokitiol with zinc oxide did not show synergistic effects. These results showed that the liquid and vapor phases of hinokitiol have strong anti-oral bacteria abilities. Hinokitiol has the potential to be applied in oral health care products, dental materials, and infection controls to exert antimicrobial activity.

Background: Herpesviruses may play roles in the development of periodontal diseases. The present study evaluated the relationships between herpesviruses and the severity of periodontitis.Methods: Periodontal status in terms of gingival inflammation, bleeding on probing, probing depth, and clinical attachment loss of 20 participants was evaluated. The presence of herpes simplex virus (HSV), human cytomegalovirus (HCMV), or Epstein‐Barr virus type 1 (EBV‐1) in six subgingival plaques from each participant was examined by nested‐polymerase chain reaction techniques.Results: Among the 120 sites examined, the prevalence of HCMV (51.7%) was higher than HSV (30.8%) followed by EBV‐1 (4.2%). The prevalence of HSV or HCMV was significantly higher in the subgroups that had lower plaque index (<1). However, the prevalence of HSV was significantly higher in the subgroup that had higher gingival index (≥2), positive bleeding on probing, deeper probing depth (≥4 mm), or higher clinical attachment loss (≥4 mm). Moreover, the prevalence of EBV‐1 was significantly higher in the subgroup that had higher probing depth (≥4 mm). Coinfection of HSV and HCMV was significantly associated with the sites that had higher gingival index (≥2) or positive bleeding on probing. Coinfection of any two herpesviruses was also associated with higher probing depth (≥4 mm) or higher clinical attachment loss (≥4 mm).Conclusions: This study demonstrated that HSV is related to the severity of periodontal diseases in terms of clinical attachment loss. Coinfection of any two herpesviruses may also play roles. J Periodontol 2004;75:1479‐1485.