Effect of an Oral Frailty Measures Program on Community-Dwelling Elderly People: A Cluster-Randomized Controlled Trial.

INTRODUCTION: Oral frailty describes a trivial decline in the oral function and is considered to be related to frailty. Thus, effective management of oral frailty could prevent or ameliorate physical frailty and the need for care. However, there is a lack of consensus regarding specific interventions for oral frailty. In this cluster-randomized controlled trial, we investigated the effects of a newly developed oral frailty measures program mentored by dentists and dental hygienists for elderly people in a clinical setting. METHODS: Of 3,296 participants included in a field survey, 219 who regularly visited dental clinics and met at least 3 of the following 6 criteria for oral frailty were considered eligible: <20 natural teeth, decreased chewing ability, decreased articulatory oral-motor skills, decreased tongue pressure, and substantial subjective difficulties in eating and swallowing. After applying the inclusion and exclusion criteria, we studied 51 patients in the intervention group (14 men and 37 women; mean age, 78.6 years) and 32 patients in the control group (7 men and 25 women; mean age, 78.0 years). We implemented a 12-week oral frailty measures program only for the intervention group. The program included preparatory oral exercises, mouth-opening training, tongue pressure training, prosodic training, and masticatory training. Primary outcome measures were the chewing ability score, articulatory oral motor skill for /ta/, tongue pressure, subjective difficulty in eating tough foods, and subjective difficulty in swallowing. We compared baseline characteristics using the Mann-Whitney U and χ2 tests for continuous and categorical variables, respectively. A repeated-measures two-way ANOVA was used to determine the efficacy of independent intervention variables, following the Wilcoxon signed-rank test. The groups (intervention/control) and time (baseline/week 12) were the independent variables. Oral frailty measures were the dependent variables. RESULTS: Baseline characteristics and assessment results were similar between groups. We observed significant improvements in the intervention group in terms of articulatory oral motor skill for /ta/ and tongue pressure (p < 0.001). No improvements were observed in the control group. DISCUSSION/CONCLUSION: Our results suggest that our oral frailty measures program effectively alleviates oral frailty. Future studies are needed to clarify the impact on preventing physical frailty and improving the nutritional status.

Fluoride-sensitivity of growth and acid production of oral Actinomyces: comparison with oral Streptococcus.

Actinomyces are predominant oral bacteria; however, their cariogenic potential in terms of acid production and fluoride sensitivity has not been elucidated in detail and compared with that of other caries-associated oral bacteria, such as Streptococcus. Therefore, this study aimed to elucidate and compare the acid production and growth of Actinomyces and Streptococcus in the presence of bicarbonate and fluoride to mimic conditions in the oral cavity. Acid production from glucose was measured by pH-stat at pH 5.5 and 7.0 under anaerobic conditions. Growth rate was assessed by optical density in anaerobic culture. Although Actinomyces produced acid at a lower rate than did Streptococcus, their acid production was more tolerant of fluoride (IDacid production 50 = 110-170 ppm at pH 7.0 and 10-13 ppm at pH 5.5) than that of Streptococcus (IDacid production 50 = 36-53 ppm at pH 7.0 and 6.3-6.5 ppm at pH 5.5). Bicarbonate increased acid production by Actinomyces with prominent succinate production and enhanced their fluoride tolerance (IDacid production 50 = 220-320 ppm at pH 7.0 and 33-52 ppm at pH 5.5). Bicarbonate had no effect on these variables in Streptococcus. In addition, although the growth rate of Actinomyces was lower than that of Streptococcus, Actinomyces growth was more tolerant of fluoride (IDgrowth 50 = 130-160 ppm) than was that of Streptococcus (IDgrowth 50 = 27-36 ppm). These results indicate that oral Actinomyces are more tolerant of fluoride than oral Streptococcus, and bicarbonate enhances the fluoride tolerance of oral Actinomyces. Because of the limited number of species tested here, further study is needed to generalize these findings to the genus level.

Quantification and identification of bacteria in acrylic resin dentures and dento-maxillary obturator-prostheses.

PURPOSE: To quantify and identify bacteria detected in acrylic resin dentures and dento-maxillary obturator-prostheses after long-term use. METHODS: The internal layer of denture bases from 13 daily-use removable acrylic resin dentures was sampled, while the inner fluid samples/no-fluid samples of obturators were collected from 11 in-use acrylic resin dento-maxillary obturator-prostheses. Samples were cultured, and isolated bacteria were counted and identified by molecular biological methods. RESULTS: Bacteria were detected in five (38.5%) acrylic resin dentures and six (54.5%) acrylic resin obturators. Four Lactobacillus species and one Propionibacterium species were isolated from three repaired denture bases, and from two non-repaired dentures, two Actinomyces species and Streptococcus mutans were isolated. On the other hand, 17 bacterial species, belonging to the family and genera of Olsenella, Bacillus, Citrobacter, Enterobacteriaceae, Lactobacillus, Pantoea, Peptoniphilus, Klebsiella and Pseudomonas, were isolated from obturators. Several species of viable bacteria were detected in acrylic resin denture bases and obturators.

Effects of the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) on bacterial viability and metabolism.

The antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) is a strong bactericide when unpolymerized and has the potential to be utilized in various resinous biomaterials. To analyze the antibacterial characteristics of this monomer in detail, the ability of high concentrations of unpolymerized MDPB to kill Streptococcus mutans in planktonic or biofilm forms within a short time-period of contact, and the inhibitory effects of low concentrations of MDPB on the metabolic function of S. mutans, were examined. High concentrations of MDPB showed effective killing of planktonic and biofilm S. mutans cells within 60 s, and complete killing was obtained by contact with 1,000 µg ml(-1) of MDPB for 60 s. At a concentration of 4-8 µg ml(-1) , MDPB demonstrated growth inhibition, inducing elongation of the lag phase and of the doubling time, when the bacterial number was low. Inhibition of the production of acid from S. mutans by 8 µg ml(-1) of MDPB may have been caused by the inhibition of lactate dehydrogenase activity. At high concentrations, MDPB is lethal to both planktonic and biofilm forms of S. mutans in a short time-period, and at low concentrations, MDPB inhibits metabolic enzymatic activity.

Inhibitory effect of Ti-Ag alloy on artificial biofilm formation.

Titanium-silver (Ti-Ag) alloy has been improved for machinability and mechanical properties, but its anti-biofilm properties have not been elucidated yet. Thus, this study aimed to evaluate the effects of Ti-Ag alloy on biofilm formation and bacterial viability in comparison with pure Ti, pure Ag and silver-palladium (Ag-Pd) alloy. Biofilm formation on the metal plates was evaluated by growing Streptococcus mutans and Streptococcus sobrinus in the presence of metal plates. Bactericidal activity was evaluated using a film contact method. There were no significant differences in biofilm formation between pure Ti, pure Ag and Ag-Pd alloy, while biofilm amounts on Ti-20% Ag and Ti-25% Ag alloys were significantly lower (p<0.05). In addition, Ti-Ag alloys and pure Ti were not bactericidal, although pure Ag and Ag-Pd alloy killed bacteria. These results suggest that Ti-20% Ag and Ti-25% Ag alloys are suitable for dental material that suppresses biofilm formation without disturbing healthy oral microflora.

Fluoride released from glass-ionomer cement is responsible to inhibit the acid production of caries-related oral streptococci.

OBJECTIVES: Glass-ionomer cements (GICs) are known to have inhibitory effects on bacterial growth, but the biochemical mechanism of this property has not been fully understood. This study aimed to evaluate inhibitory effects of GIC on the acid production of caries-related oral streptococci, and to identify the components responsible for the inhibition. METHODS: An eluate was prepared by immersing set GIC in phosphate-buffered saline at 37 degrees C for 24h. Fluoride and other elements in the eluate were quantified by fluoride ion electrode and atomic absorption photometry, respectively. Streptococcus mutans NCTC 10449 and Streptococcus sanguinis NCTC 10556 were used to evaluate the pH fall and the rate of acid production after the addition of glucose in the presence or absence of the eluate. Acidic end products from glucose were also assayed by carboxylic acid analyzer. RESULTS: The eluate contained silicon (1.24+/-0.26 mM), fluoride (0.49+/-0.02 mM) and aluminum (0.06+/-0.00 mM), and inhibited the pH fall and the acid production rate of both streptococci at acidic pH, with a concomitant decrease in lactic acid production. These effects were comparable to those of a potassium fluoride solution containing the same concentration of fluoride as the eluate. SIGNIFICANCE: These results indicate that the GIC eluate inhibits the acid production of caries-related oral streptococci at acidic pH and that the effect is due to fluoride derived from the GIC. Thus, adjacent to GIC fillings, bacterial acid production and the subsequent bacterial growth may decrease, establishing a cariostatic environment.