There is no information available regarding the physiological effects of nitrous oxide （N₂O）-oxygen inhalation sedation for patients with severe motor and intellectual disabilities （SMID） and healthy adults （HA）. To evaluate this, we assessed autonomic functions with heart rate （HR） variability during dental treatment under N₂O-oxygen inhalation sedation. Nine SMID patients and 9 HA patients were randomly assigned to inhale 0％, 30％ or 40％ of N₂O on each treatment day. HR （ECG） and respiration rate （piezo band） were measured in the supine position after resting for 5 min as a baseline, followed by 5-min N₂O-oxygen inhalation, infiltration anesthesia （IA）, and dental scaling （DS）. The high frequency （0.15-0.4Hz：HF） component of HR was defined as a parasympathetic nerve activity and the ratio of the low frequency （0.04-0.15Hz：LF） component to HF （LF/HF） was defined as a cardiac sympathetic nerve activity. Sedations inducing increases in HF and decreases in LF/HF were considered effective. In HA patients, HR was lower during 5-min N₂O inhalation and IA compared to baseline. In SMID patients, it was lower during 5-min N₂O inhalation, but similar during IA, and higher during DS compared to baseline. HF increased after 5-min N₂O inhalation until IA in both HA and SMID patients. This change in HF was remarkable at 30％ N₂O in HA patients, and 40％ N₂O in SMID patients. LF/HF was lower during 5-min N₂O inhalation and IA compared to baseline only in SMID patients, especially at 40％ N₂O. These results suggest that N₂O-oxygen inhalation with relatively higher concentration is effective even in patients with severe motor and intellectual disabilities, and the dental stress is alleviated by using N₂O-oxygen inhalation for them.

Although it is important to select appropriate toothbrushes for special needs patients, there is no objective functional index for such selection.

In this study, we investigated the effects of brushing force and toothbrush specifications on cleaning efficiency using a flat model for four kinds of toothbrush：three types with rounded bristles of different hardness, and one type with super-tapered bristles.

There was a positive correlation between brushing force and cleaning efficiency. It has been shown that controlling the brushing force is important to obtain an appropriate cleaning effect. Toothbrushes with super-tapered bristles and soft bristles had lower cleaning efficiency than toothbrushes with rounded bristles and hard bristles. This result was thought to be due to the fact that the tips of the bristles are thin and bend greatly when brushed, making it difficult to transmit force to the surface to be cleaned.

In this study, differences in cleaning efficiency were observed with different brushing force and different bristle specifications using a flat model. It is suggested that understanding and selecting the performance of the toothbrush could compensate for the diverse brushing skills of special needs patients and achieve efficient brushing.

The purpose of this study was to investigate the dental caries status of children and students with intellectual disabilities. We conducted a questionnaire survey on the results of school dental health examinations at eight special support schools for children and students with intellectual disabilities in a specific prefecture. We also compared the results obtained from the questionnaire survey with those of the same year’s survey published by the prefecture to identify the characteristics of each medical area in the prefecture.

The results were as follows：

Consultation Rate：The number of children and students with intellectual disabilities attending eight special support schools was 1,133 and the number of examinees was 1,092. The consultation rate for all children and students was 96.4％. In elementary, middle, and high special support schools, the consultation rates were 98.0％, 95.8％, and 95.3％ respectively. The rate was significantly lower in high school compared to elementary school.

Dental Caries Status：The dental caries status of children and students with intellectual disabilities in each age group was compared to the status published by the prefecture. Both the morbidity and non-treatment rate of dental caries in the special support schools, excluding the morbidity in the special support elementary school, were slightly higher than those published by the prefecture.

Medical Area Differences：The medical area with the worst dental caries status of children and students with intellectual disabilities did not have any specialists certified by the Japanese Society for Disability and Oral Health. The morbidity and non-treatment rate in this medical area were 53.1％ and 38.8％, respectively. Particularly, the dental caries status of the special support elementary school in this medical area was significantly worse than the status in the same area published by the prefecture.

Specialist Area：The area with the worst dental caries status of children and students with intellectual disabilities was the farthest from the only medical area where specialists worked. The dental caries status in the worst area was significantly worse than the status in the specialist area. We suggest that improvements, such as the employment of a specialist, should be considered.

The actual condition of treatment using medication for behavioral control was investigated for 1- to 12-year-old patients who visited our department over the past 7 years. Of the 116 patients identified, 145 cases received dental treatment and oral surgery performed under general anesthesia （GA） and intravenous sedation （IVS）. Among these 116 patients, 47 had a disability （e.g., developmental disorder, intellectual disability）. No significant difference in age or sex was found between patients with and without disability. Many referrals were made from primary and nearby dentists for patients without disability. On the other hand, in patients with disability, referrals from others were conspicuous. Some patients with disability had no referral. Among the patients, 92 and 53 received GA and IVS as the behavioral control method, respectively, and the proportion of patients receiving IVS showed an increasing tendency over the study period. Caries treatment was the most common type of treatment, especially in patients with disability. Many cases involving caries treatment received GA, while many involving tooth extraction and oral surgery received IVS. Differences were seen in the social backgrounds of the patients according to the presence of disability, as well as in the required treatment and behavioral control method. These findings suggest that behavioral control using medication can be provided by medical specialists familiar with the general management of pediatric patients. It seemed to be reasonable that GA and IVS were carried out safely by anesthesiologists or pediatricians in regional core hospitals, such as our hospital.