In recent years, magnesium hydroxide has been widely studied due to its bioactivity and biocompatibility. The bactericidal effects of magnesium hydroxide nanoparticles on oral bacteria have also been reported. Therefore, in this study, we investigated the biological effects of magnesium hydroxide nanoparticles on inflammatory responses induced by periodontopathic bacteria. Macrophage-like cells, namely J774.1 cells, were treated with LPS derived from Aggregatibacter actinomycetemcomitans and two different sizes of magnesium hydroxide nanoparticles (NM80/NM300) to evaluate their effects on the inflammatory response. Statistical analysis was performed using an unresponsive Student’s t-test or one-way ANOVA followed by Tukey’s post hoc test. NM80 and NM300 inhibited the expression and secretion of IL-1β induced by LPS. Furthermore, IL-1β inhibition by NM80 was dependent on the downregulation of PI3K/Akt-mediated NF-κB activation and the phosphorylation of MAPK molecules such as JNK, ERK1/2, and p38 MAPK. By contrast, only the deactivation of the ERK1/2-mediated signaling cascade is involved in IL-1β suppression by NM300. Although the molecular mechanism involved varied with size, these results suggest that magnesium hydroxide nanoparticles have an anti-inflammatory effect against the etiologic factors of periodontopathic bacteria. These properties of magnesium hydroxide nanoparticles can be applied to dental materials.

IntroductionSince the needs for dental care among older adults in Japan are expected to increase in the future, this study aimed to examine the influence of ageism among dental students and clinical trainees on the attitude towards the older adults in dental care.Materials and MethodsIn 2022, we conducted a questionnaire survey of 9th‐, 11th‐semester dental students and first‐year clinical trainees enrolled at Kyushu Dental University, using the Japanese version of Ageism Scale for Dental Students (ASDS‐J), Japanese version of Fraboni Scale of Ageism (FSA‐J). Questions on intention to provide dental care to the older adults, relationships with the older adults and living with the older adults were also surveyed.ResultsThere were 162 participants (84 males and 78 females), and the response rate was 71.7%. The participants were divided into the positive group for dental care to older adults (68 respondents) and the negative group (94 respondents). The ASDS‐J score of the negative group was significantly higher than that of the positive group [49 (36–66) vs. 52 (34–88), p < .001]. The binomial logistic regression analysis revealed that the odds ratio of being negative attitude was 1.1 per one point of ASDS‐J (95% confidence interval: 1.0–1.2) in the model adjusted for student grade, interaction with the older adults, gender, experience living with the older adults and FSA‐J.ConclusionThese findings suggest that ageism specific to dental students and clinical trainees (as assessed using the ASDS‐J) was independently correlated with negative attitudes towards dental care for older adults.