Usefulness of the newly developed artificial denture plaque for practical denture care training.

OBJECTIVES: The aim of this study was to investigate whether the newly developed artificial dental plaque (A-DP) is useful as an educational tool for denture care of dental hygienist that compared it with conventional artificial dental plaque from the viewpoint of practical skills. MATERIAL AND METHODS: The 125 dental hygienist school students and 26 dental hygienists who had clinical experience were subjected a practical training of denture plaque control using the conventional denture plaque (C-DP) and the A-DP. The questionnaires based on the semantic differential method were used to survey whether the A-DP is similar to the real denture plaque (R-DP). Factor analysis by rotation of promax was carried out. RESULTS: In the results of the factor analysis, the two factors could be detected in students and three factors in dental hygienists. The total score of each denture plaque was calculated for each factor, and correlation coefficient was examined. There was significant correlation between the A-DP and the R-DP at the first factors, both students and dental hygienists. C-DP was not similar to R-DP in all factors. CONCLUSIONS: These results suggested that A-DP resembles R-DP better than C-DP. It was concluded that the A-DP was similar to the R-DP and could be a potent educational tool for practical denture care.

Relationship between periodontal status and intellectual function among community-dwelling elderly persons.

OBJECTIVE: The aim of this study was to indicate the relationship between periodontal status and intellectual function in the elderly. BACKGROUND: Periodontal status has been shown to be related to demographic, socioeconomic, and psychological status. Intellectual function is a significant indicator of health status. Nevertheless, the relationship between periodontal status and intellectual function has not been elucidated in detail among the elderly. MATERIALS AND METHODS: A total of 152 community-dwelling elderly persons, aged 70-74 years, were enrolled in the study. Periodontal status was evaluated using the WHO Community Periodontal Index of Treatment Needs (CPITN). Intellectual function was assessed by four neuropsychological tests: Raven's Coloured Progressive Matrices (RCPM) test, the Verbal Paired Associates 1 (VerPA) task and the Visual Paired Associates 1 (VirPA) task, extracted from the Wechsler Memory Scale Revised Edition, and the Block Design subtest, extracted from the Wechsler Adult Intelligence Scales, Third Edition. Correlations between CPITN and each test were examined using Spearman rank correlation coefficients. The ordinal regression model was constructed with CPITN as the dependent variable and neuropsychological test as the principal independent variable to adjust for demographic factors, general health, lifestyle and oral health behaviour. RESULTS: Significant correlations were found between the RCPM test, the VerPA task, the Visual Paired Associates 1 and CPITN. In the ordinal regression model, CPITN was significantly related to measures of RCPM after adjusting for demographic factors, general health status, lifestyle and oral health behaviour. CONCLUSION: Intellectual function is considered a significant indicator of periodontal status among community-dwelling elderly persons.

Effect of mastication on functional recoveries after permanent middle cerebral artery occlusion in rats.

OBJECTIVES: We evaluated whether solid feed is more effective for functional recoveries than liquid feed in rats with ischemic brain injury after permanent middle cerebral artery occlusion (MCAO). METHODS: A total of 36 male Wistar/ST rats were subjected to MCAO or sham surgery. After MCAO or sham surgery, all rats were provided liquid feed for 14 days. Then, all rats were divided into 3 groups: the solid feeding group, the liquid feeding group, and the solid feeding group of sham. Effect of mastication on functional recoveries after permanent MCAO in rats was evaluated by the limb placement test and Morris water maze (MWM) task. RESULTS: After surgery, limb placement test scores were equal in both MCAO groups. In the acquisition trials of MWM task, statistically significant differences in escape latency were observed between the liquid feeding group and sham groups at all days, and between the solid feeding group and sham groups at days 3 and 4 of the trials. In the probe trial, statistically significant differences in time spent were observed between the liquid feeding group and sham group. On day 5 of acquisition trials, the time spent in the periphery of the pool in MWM task was significantly different among the 3 groups. CONCLUSION: This study suggested that solid diet mastication could be effective for the rehabilitation of sensorimotor and learning/memory dysfunction induced by cerebral infarction.

Effect of wearing a palatal plate on swallowing function.

PURPOSE: The purpose of this study was to determine the effect of wearing a palatal plate on swallowing function. METHODS: The subject group consisted of 10 healthy, fully dentate males. Two experimental palatal plates (EPP) were used in this study: one was 1.4mm thick (EPP1), and the other was 2.8mm thick (EPP2). Tongue movements and swallowing sounds were simultaneously recorded. The position of the surface of the tongue was recorded by using ultrasound diagnostic equipment in the sagittal plane. Swallowing tests were performed under three conditions: without EPP (WOE), with EPP1 (WP1), and with EPP2 (WP2). Swallowing index (SI) and tongue contact time (TCT) was calculated. RESULTS: The value of SI was lowest under WOE, and highest under WP2, with a statistically significant difference. There was no statistical significance, however, between SI under WOE and that under WP1. The value of TCT was longest under WOE, and shortest under WP2, with a statistically significant difference. CONCLUSIONS: This investigation suggests that the thickness of a palatal plate influences SI and TCT, which correlate with swallowing function.

Mandibular residual ridge shape and the masticatory ability in complete denture wearers.

PURPOSE: The purpose of this study was to investigate the influence of mandibular residual ridge shape on the masticatory ability in complete denture wearers. METHODS: The subject group consisted of 199 complete denture wearers. The mandibular residual ridge of each subject was evaluated using a replica of the ridge which was obtained with heavy-body silicone impression material. The basal area of each replica was measured with a digitizer. The volume and the height of each replica were also calculated. The masticatory ability of each subject was evaluated using a-25-item food intake questionnaire method by authors. The masticatory score of each subject was calculated to represent the masticatory ability. Furthermore, all subjects were divided into three groups (S, M, L group) according to the value of the basal area. RESULTS: There were statistically significant correlations between the basal area of the residual ridge and the masticatory score (r = 0.366, p < 0.01), and also the volume of the residual ridge and the masticatory score (r = 0.314, p < 0.01). The basal area of the residual ridge, the volume of the residual ridge, and the masticatory score of the L group (29 persons) were statistically larger than those of the M group (136 persons) and the S group (34 persons) (p < 0.05), and those values in the M group were statistically larger than those of the S group (p < 0.05). CONCLUSION: It was confirmed that the basal area of denture foundation of the mandible had an influence on the masticatory ability in complete denture wearers.

CYP24 promoter activity is affected by mechanical stress and mitogen-activated protein kinase in MG63 osteoblast-like cells.

PURPOSE: For bone homeostasis, vitamin D plays an important role in the regulation of calcium. The enzyme CYP24 inactivates vitamin D and is involved in its regulation. However, the mechanism of expression of CYP24 in osteoblastic cells under mechanical stress is not clear. In this study we investigated CYP24 promoter activity in stretched osteoblastic cells and the participation of mitogen-activated protein kinase (MAPK) in expression of CYP24. METHODS: MG63 osteoblastic cells were cultured on silicon-bottomed plates. Cells were transfected with a reporter gene that contained a CYP24 promoter. After activated vitamin D, 1,25(OH)2D3, was added or not added, cells were stretched. Stretched and non-stretched cells were investigated by luciferase dual assay. Cells were also investigated similarly using medium with an ERK1/2 inhibitor or p38 inhibitor. RESULTS: The CYP24 promoter was activated by 1,25(OH)2D3 and the promoter activity decreased in stretched cells. Inhibitor of MAPK decreased CYP24 promoter activity. However, CYP24 promoter activity decreased with mechanical stress after addition of p38 inhibitor, while it did not decrease with mechanical stress after addition of ERK1/2 inhibitor. The CYP24 promoter was not activated without 1,25(OH)2D3 in any case. CONCLUSION: Mechanical stress and MAPK control CYP24 promoter activity in the presence of Vitamin D in MG63 osteoblast-like cells.