###### Abstract  
Hemophilia is a congenital disorder associated with impaired blood clotting. Routine dental intervention to prevent oral bleeding in patients with hemophilia is considered important, but its effectiveness remains unknown. In the present study, we evaluated the effect of continual dental support on periodontal status and oral health habits in young patients with hemophilia. Of the 168 young patients with hemophilia who visited our clinic for 5 years, we selected subjects who had visited annually since 2015 and were in the mixed and permanent dentitions. To evaluate the periodontal status of these subjects, Community Periodontal Index (CPI) values in the molars and anterior teeth were measured. In addition, a questionnaire regarding oral health habits, including floss use, frequency of brushing by parents, and attending a family dentist, was administered to the subjects and their parents. In the patients with mixed dentition, the CPI values for the upper right molars and lower left central incisor decreased significantly in later years compared with the first year (\(p<0.05\)). In the patients with permanent dentition, only one year recorded a significant decrease in CPI values compared with the first year (\(p<0.05\)), localized in the upper right molars. The results of the questionnaire revealed that continual dental support improved dental loss use and the frequency of brushing by parents only in the mixed dentition group. Furthermore, these oral health habits significantly affected CPI values only in the mixed dentition group (\(p<0.01\)). These results suggest that continual dental support improves the periodontal condition and oral health habits of hemophilic patients, especially those with mixed dentition.  
hemophilia; continual dental support; periodontal status; oral health habits +
Footnote †: Corresponding: takitomo@hiroshima-u.  
which pediatricians evaluate coagulation factor replacement therapy, orthopedic surgeons assess hemophilic arthritis, and physical therapists provide rehabilitation. In addition to these medical treatments, we have been providing dental checkups, oral health education, and mechanical tooth cleaning since 2015. We previously conducted a survey in this outpatient clinic and compared hemophilic patients with healthy controls of the same age, which resulted in the periodontal status of hemophilic patients being poorer than that of healthy children [5].  
When performing surgical procedures on patients with hemophilia, coagulation factor replacement may be necessary to prevent excessive bleeding [6]. Excessive bleeding from the oral cavity should also be considered in patients with hemophilia, and particular attention should be paid to periodontal tissue, which has a high frequency of bleeding in the oral cavity. Systematic reviews, mostly from the general population, found that the risk of periodontitis is approximately two to five times higher in patients with poor oral hygiene than in patients with good oral hygiene. Oral care habits, including regular toothbrushing and dental visits, can also reduce the risk [7]. However, the impact of regular, continuous dental interventions on the periodontal status and oral health habits of patients with hemophilia is unclear.  
We have investigated the periodontal status and oral health habits of young patients with hemophilia for up to 5 years. In the present study, we analyzed the effects of continual dental support on periodontal status and oral health habits in young patients with hemophilia and compared the results in a mixed dentition group and a permanent dentition group.