“…Although a previous study stated that oral hygiene practices such as TB and DF were not associated with periodontitis (Merchant et al., ), the recent review showed that infrequent TB was related to having severe periodontal disease (Zimmermann et al., ). Another recent study reported that the mean of dental plaque and calculus scores were reduced by TB (Harvey et al., ). Cochrane review recommended TB twice a day to prevent caries (Marinho, Higgins, Sheiham, & Logan, ), but the recent systematic review stated that the effect of frequency of toothbrushing to dental caries is unclear and the evidence of toothbrushing twice a day was not strong (Kumar, Tadakamadla, & Johnson, ).…”