However, this study had several limitations. First, we did
not measure the intra-examiner error which is important
to clinical research with CPI, to alleviate participant’s sufferings. Second, we investigated the current state of
smoking in questionnaires, so ex-smokers might have
been classified as non-smoker group in questionnaires.
Periodontal health of ex-smokers might have been affected
by past smoking experience and this result might
have influenced on the result of multiple regression analysis
which was adjusted for smoking variables. Therefore,
further studies need to evaluate smoking status of participants
considering the number of cigarettes, experience
and period of smoking.