Study protocol for a multi-center, randomized controlled trial to develop Japanese denture adhesive guidelines for patients with complete dentures : the Denture Adhesive Guideline trial : study protocol for a randomized controlled trial

Background: Denture adhesives, characterized as medical products in 1935 by the American Dental Association, have been considered useful adjuncts for improving denture retention and stability. However, many dentists in Japan are hesitant to acknowledge denture adhesives in daily practice because of the stereotype that dentures should be inherently stable, without the aid of adhesives. The aim of this study is to verify the efficacy of denture adhesives to establish guidelines for Japanese users. The null hypothesis is that the application of denture adhesives, including the cream and powder types, or a control (isotonic sodium chloride solution) would not produce different outcomes nor would they differentially improve the set outcomes between baseline and day 4 post-application. Methods: This ten-center, randomized controlled trial with parallel groups is ongoing. Three hundred edentulous patients with complete dentures will be allocated to three groups (cream-type adhesive, powder-type adhesive, and control groups). The participants will wear their dentures with the denture adhesive for 4 days, including during eight meals (three breakfasts, two lunches, and three dinners). The baseline measurements and final measurements for the denture adhesives will be performed on the first day and after breakfast on the fourth day. The primary outcome is a general satisfaction rating for the denture. The secondary outcomes are denture satisfaction ratings for various denture functions, occlusal bite force, resistance to dislodgement, masticatory performance, perceived chewing ability, and oral health-related quality of life. Between-subjects comparisons among the three groups and within-subjects comparisons of the pre- and post-intervention measurements will be performed. Furthermore, a multiple regression analysis will be performed. The main analyses will be based on the intention-to-treat principle. A sample size of 100 subjects per group, including an assumed dropout rate of 10 %, will be required to achieve 80 % power with a 5 % alpha level. Discussion: This randomized clinical trial will provide information about denture adhesives to complete denture wearers, prosthodontic educators, and dentists in Japan. We believe this new evidence on denture adhesive use from Japan will aid dentists in their daily practice even in other countries

Effect of masticatory stimulation on the quantity and quality of saliva and the salivary metabolomic profile - Fig 4

<p>Correlation between metabolite concentration of salivary volume for unstimulated <b>(A)</b> and stimulated <b>(B)</b> saliva. The relationship between metabolite concentration and salivary volume for the metabolites was significantly correlated (<i>P</i>-value<0.05, Spearman ranked correlation), and is visualized in small panels. Regression lines show the overall trends.</p

Loading plots of principal component analysis (PCA).

<p>Loading plots of principal component analysis (PCA).</p

Ranking of pathways and related correlation between unstimulated and stimulated saliva samples.

<p>Ranking of pathways and related correlation between unstimulated and stimulated saliva samples.</p

The metabolic pathways that ranked first in the pathway analysis, and using only metabolites, showed significant differences (<i>P</i><0.05, Wilcoxon matched pairs test, corrected by false discovery rate) between unstimulated and stimulated saliva samples.

<p>The red bar indicates the average concentrations of unstimulated (left) and stimulated (right) saliva. To clearly visualize the data, these data were divided by the average of unstimulated saliva.</p

Heat map of salivary metabolite concentrations.

<p>Red, white, and blue indicate relatively higher, average and lower concentrations, respectively. Those identified by the black box (bottom of the figure) were from the stimulated saliva samples, and the others were from the unstimulated samples. Clustering was conducted using Pearson correlation. Metabolite names are colored depending on the corrected <i>P</i>-values between the 2 groups.</p

The Effect of TBB, as an Initiator, on the Biological Compatibility of PMMA/MMA Bone Cement

Acrylic bone cement is widely used in orthopedic surgery for treating various conditions of the bone and joints. Bone cement consists of methyl methacrylate (MMA), polymethyl methacrylate (PMMA), and benzoyl peroxide (BPO), functioning as a liquid monomer, solid phase, and polymerization initiator, respectively. However, cell and tissue toxicity caused by bone cement has been a concern. This study aimed to determine the effect of tri-n-butyl borane (TBB) as an initiator on the biocompatibility of bone cement. Rat spine bone marrow-derived osteoblasts were cultured on two commercially available PMMA-BPO bone cements and a PMMA-TBB experimental material. After a 24-h incubation, more cells survived on PMMA-TBB than on PMMA-BPO. Cytomorphometry showed that the area of cell spread was greater on PMMA-TBB than on PMMA-BPO. Analysis of alkaline phosphatase activity, gene expression, and matrix mineralization showed that the osteoblastic differentiation was substantially advanced on the PMMA-TBB. Electron spin resonance (ESR) spectroscopy revealed that polymerization radical production within the PMMA-TBB was 1/15&ndash;1/20 of that within the PMMA-BPO. Thus, the use of TBB as an initiator, improved the biocompatibility and physicochemical properties of the PMMA-based material