There are many causes for oral malodour, and 
tongue coating, periodontitis, deep caries and unfitted 
restorations are main causes of bad breath odour. It is not 
difficult to reduce oral malodour by careful examination 
and proper treatment. However, we sometimes encounter 
oral malodour associated with other problem. Here, we 
report a case of persistent oral malodor associated with 
periodontitis caused by tooth perforation. The patient (a 
41 year old, female) had visited our breath clinic 
complaining of a strong breath odor. Oral malodor was 
detected by several tests including organoleptic test, 
portable sulfide monitor and gas chromatography. She had 
consulted two dentists to reduce her breath odor. The 
dentists performed periodontal treatments including 
scaling, and root planing. However, her oral malodour did 
not decrease, and she had been worrying about her breath 
odor for 15 years. The patient’s oral hygiene was not bad 
at the first visit. Periodontal condition was not severe 
except tooth 24, and there were deep pockets in the 
proximal of the tooth. We performed initial periodontal 
treatment, but the condition of 24 did not change. We 
performed a surgical inspection and perforation of the 
tooth 24 was considered to be the main cause of 
periodontitis. Large number of periodontopathic bacteria 
was detected from the saliva and examination revealed the 
strong oral malodor. After extraction of the causative  tooth, periodontal condition improved, and bacterial 
number was decreased. The patient’s breath odor was 
reduced to less than the threshold level and she was free 
from long-lasting worries on oral malodor. 

Keywords: Oral malodor; Periodontitis; Perforation; 
Bacterial Examination