Manual toothbrushes, self-toothbrushing, and replacement duration to remove dental plaque and improve gingival health: A scoping review from recent research.

OBJECTIVE: To investigate characteristics of manual toothbrushes, self-toothbrushing methods, and replacement duration of manual toothbrushes that effectively remove dental plaque, reduce gingivitis, and promote gingival health. STUDY DATA AND SOURCES: PubMed-MEDLINE, Scopus and Central Register Cochrane of Controlled trials (CENTRAL) were searched for randomized control trials (RCTs) from 01 January 2018 to 12 December 2023. Articles were subjected for including participants aged six years and older with a study duration of at least four weeks to investigate the efficacy of manual toothbrushes used self-toothbrushing. To investigate the appropriate time to replace manual toothbrushes, this study was focused on the physical properties of the bristles and changes in the microorganisms present in the bristles over time. STUDY SELECTION: Of 1520 retrieved articles, 26 studies were included after screening. The total number of manual toothbrushes was 40 and 5 kinds of self-toothbrushing techniques were selected in the review. 4 studies investigated the changes the physical properties bristles of manual toothbrushes. CONCLUSIONS: Among manual toothbrushes, the cross-angle and indicator bristles were found to significantly improve dental plaque index and gingival condition. Most toothbrushes with soft bristles had a trend of superior dental plaque removal and gingivitis improvement efficacy. Toothbrush with end-round shape bristles tip has tended to reduce the dental plaque and gingival index scores. Studies reported that brushing twice a day for at least two minutes using the Bass method had a positive effect on the dental plaque and gingival index. Further research is required to investigate the relationships between property physical bristle and clinical intraoral indices to clarify the replacement duration of manual toothbrushes. CLINICAL SIGNIFICANCE: The findings of this study could guide people's daily self-brushing habits, thereby aiding the prevention of periodontal disease. Moreover, our findings suggest the need for strategic clinical trial designs to verify the ideal timing to replace manual toothbrushes.

Prevalence of oral Capnocytophaga species and their association with dental plaque accumulation and periodontal inflammation in middle­aged and older people.

Capnocytophaga species are commonly found in human oral microbiome. The aim of the present study was to understand the association of the prevalence of oral Capnocytophaga species with oral hygiene and periodontal inflammation. A total of 136 patients (median age 72 years) who visited the Hiroshima University Hospital (Hiroshima, Japan) between April 2021 and June 2023 were enrolled. Swab samples were obtained from the tongue surface. DNA from Capnocytophaga species (C. ochracea and C. sputigena) was detected by real-time PCR analysis. Dental plaque accumulation was observed to assess the oral hygiene condition of participants. Additionally, clinical periodontal inflammation was assessed with periodontal inflamed surface area (PISA) scores. Clinical confounding factors such as age, sex, lifestyle-related disease, remaining teeth and denture wearing between Capnocytophaga species-positive and -negative groups were adjusted with a propensity score matching method. Mann-Whitney U and χ2 or Fisher's exact test were employed for statistical analysis. The prevalence rate was 67.6% for oral C. ochracea and 83.1% for C. sputigena. C. ochracea-positive participants showed significantly higher plaque control record scores (an indicator of dental plaque accumulation) than C. ochracea-negative participants (P=0.03). Additionally, C. ochracea/C. sputigena dual-positive participants exhibited significantly higher plaque control record and PISA scores than non-dual-positive participants (P=0.01 and P=0.04, respectively). Propensity score matching was conducted in the C. ochracea/C. sputigena dual-positive group and the non-dual-positive group for adjustment of clinical factors, resulting in 51 matched patient pairs. C. ochracea/C. sputigena dual-positive participants had significantly higher plaque control record scores than non-dual-positive participants (P=0.02). The present results suggest that the prevalence of both oral C. ochracea and C. sputigena is associated with poor oral hygiene in middle-aged and older people.

[Functional model of the middle ear ossicles].

In students' dissection practice, it is very difficult to teach students the structures and functions of the middle ear ossicles. The middle ear ossicles are too small to explain their structures and functions. Models are useful in explaining these points, but there have been no models that accurately explain the movements of the middle ear ossicles and the functions of the muscles in the middle ear. This time, we have made a model of middle ear ossicles. Our ear ossicles are made of paper-mache with metal in it. The incudomalleolar and incudostapedial articulations are made of rubber. The tensor tympani and the stapedius muscles are made of wire and the two wires can be fixed by cord stoppers. Our model explains clearly the following mechanisms of the middle ear ossicles. 1. The mechanism of sound conduction system. When the sound vibrates the tympanic membrane, malleus and incus rotate together. The long process of the incus pushes the head of the stapes. The sound is amplified by leverage. 2. Attenuation of sound by contractions of tensor tympani and stapedius muscles. When a loud sound is transmitted through the ossicular system, the tensor tympani muscle pulls the malleus inward while the stapedius muscle pulls the stapes outward. These two forces oppose each other and increase rigidity of the ossicular system, thus reducing the ossicular conduction. 3. The mechanism of how paralysis of stapedius muscle, caused by an injury to the facial nerve, results in hyperacusis. 4. This model also suggests a possible reason why the pars lucida of the tympanic membrane exists.