DISCUSSION
hypofunction
HYPOFUNCTION, RECRUITMENT, PLAQUE
In this study, a change in the oral bacterial flora of the saliva/tongue coating was observed after intervention with CPC spray for 3 weeks after professional oral care. To allocate the condition of oral flora evenly to the CPC spray group and the control group, the subjects were stratified according to the high and low values of the Shannon index, an index of α‐diversity, of the salivary flora collected at the time of recruitment. After randomization, there were no significant differences in the clinical background between groups.There was no significant difference between the groups in the β‐diversity analysis on Day 1. This is due to the lack of difference in intraoral clinical indices between the CPC spray group and the control group, and professional oral care was performed in all subjects to remove the supragingival plaque before starting the study. However, after 1 and 3 weeks, the diversity of the microflora significantly changed between the CPC spray group and the control group, which is considered to reflect the effect of the intervention with the CPC spray.Regarding the specific changes in microflora according to LEfSe analysis, genus Genus No significant change in the TCI was noted after the intervention with CPC spray on day 0 and after 3 weeks. The TCI is one of the indices used to diagnose oral hypofunction in the elderly population in Japan (Minakuchi et al., The total bacterial count increased from Day 0 to 1 despite the intervention of professional oral care, which is considered to be due to the effects of the timing of sampling on diurnal variation. Since the subjects visited the dental clinic for sampling on Day 0 and after 3 weeks, there was variation in sampling time among individuals. However, the sample after waking up was collected at the home of the subjects on Day 1 and after 1 week. Since the time period directly after waking up is when the bacterial count is the highest in the day (Nolte, The limitations of this study are as follows. First, the identification of bacterial species with low occupancy is poor in 16S rRNA genetic analysis. Second, since the sequences of related species are similar in the V3–V4 region of the 16S rRNA gene, the accuracy of allocation at the species level is insufficient. Third, it is possible that the timing of sample collection was not aligned, which may have affected the bacterial count results. The sampling time of four times was not aligned within an individual and it differed among participants, especially on Day 0 and Week 3. To our knowledge, this is the first study of microflora in the saliva and tongue coating in a clinical evaluation after intervention with CPC spray; however, further study is necessary to explore the detailed changes in oral microflora induced by a CPC preparation. In conclusion, the microflora in the saliva/tongue coating changed with the use of CPC spray, with a particular change in genus 