Age-related changes in oral tactile and thermal sensation throughout adulthood.

Although the life expectancy of women is over 80 years in many countries, oral sensation has scarcely been compared between adults ≥ 80 years and younger age groups. The purpose of this study was to clarify age-related changes in oral sensation throughout adulthood. After exclusion of individuals with factors that might have confounded somatosensory performance, 123 female participants were divided into four age groups: 20-39 years, 40-59 years, 60-79 years, and 80-96 years. Perceptions of tactile and thermal sensations were examined at points on the anterior and posterior palate, anterior and posterior tongue, lower labial-attached gingiva, lower lip, and buccal mucosa; two-point discrimination was examined only on the tongue. The tactile and two-point discrimination thresholds for the anterior and posterior tongue were significantly higher in the 80-96-year-old group than in any other age group (p < 0.05). The tactile threshold for the buccal mucosa was significantly higher in the 80-96-year-old group than in the 60-79-year-old group (p < 0.05). The percentage of participants able to perceive a warm stimulus (50 °C) in the buccal mucosa was significantly lower in the 80-96-year-old group than in the 20-39-year-old group (p < 0.05). Only the topography of the warm sensation perception changed with age. This cross-sectional study suggests that oral tactile and thermal sensation for warm stimuli deteriorates with age in a site-specific manner, especially after the age of 80 years, but the same does not occur with cool stimuli.

Measurement of bristle splaying of toothbrushes using digital imaging and evaluation of plaque removal efficacy over 3 months: A randomized controlled trial (RCT).

OBJECTIVE: The aim of this study was to develop an objective method to assess the degree of bristle splaying of used manual toothbrushes and to investigate their plaque removal efficacy. METHODS: A randomized controlled trial targeting Hiroshima University students was performed to assess the plaque removal efficacy of polybutylene terephthalate (PBT) manual toothbrushes. Participants were randomly assigned to the soft toothbrush group (n = 40) or the medium toothbrush group (n = 40). A small number of participants discontinued the intervention for personal reasons in both the medium (n = 6) and soft (n = 2) toothbrush groups. Toothbrushes were collected immediately after first use (T0: baseline), after 1 month of use (T1: month 1), after 2 months of use (T2: month 3) and after 3 months of use (T3: month 6), following the allocation of a new toothbrush. The bristle surface area was measured using digital software. RESULTS: The surface area of the bristles was significantly greater at T1, T2 and T3 than at T0 in the medium toothbrush group (n = 34) and soft toothbrush group (n = 38) (P < .001). Importantly, plaque removal efficacy, calculated from a modified plaque control record score and modified patient hygiene performance score, was significantly lower at T2 than at T0 in both groups. CONCLUSIONS: Our method for evaluation of bristle splaying is considered to be reliable and reproducible. PBT toothbrushes may become less effective after two months of use.