Pressure production in oral vestibule during gum chewing.

The aim of this study was to record oral vestibule pressure (OVP) by the lip and cheek contraction during gum chewing, to examine the characteristics of these pressures and coordination between the OVP and jaw movement. The subjects were eight healthy adult men (mean age of 29·3 ± 3·3 years). An experimental plate that incorporated four pressure sensors on the midline of the upper jaw (Ch. 1), upper right canine (Ch. 2), upper right first molar (Ch. 3) and upper left first molar (Ch. 4) was used for measuring OVP. The right masseter electromyogram (EMG) was recorded simultaneously. Subjects chewed gum on the right side 20 times, and eight consecutive strokes were used for the analysis of the sequential order, maximal magnitude and duration of each OVP. Onset of OVP was observed at the molar on the non-chewing side (Ch. 4) before chewing side (Ch. 3), and offset was largely simultaneous at each site. On the chewing side (Chs. 1-3), OVP onset during the interval of EMG activity reached to the peak around the end of interval and offset in the duration of EMG activity. The maximal pressure was significantly larger at Chs. 1-3 than at Ch. 4, but no significant differences were observed in duration of pressure among each site. These results suggest that OVP is coordinated with jaw movement during gum chewing, and larger pressure is produced on the chewing side than on the non-chewing side. Our findings are quantitative indices for the evaluation of lip and cheek function during mastication.

Prevalence of torus palatinus among a group of Japanese elderly.

The purpose of this study was to examine the prevalence of torus palatinus (TP) among Japanese elderly and to identify the factors associated with the formation of TP. The subjects were adults aged over 60, who lived independently in the community and attended lectures once a week at the Senior Citizens' College in Osaka prefecture during 2007 and 2008. A total of 664 subjects, including 294 men and 370 women, were examined, and the mean age was 66·5±4·2 (s.d.). After informed consent was obtained, participants responded to a questionnaire and underwent clinical examination consisting of dental status, temporomandibular symptoms and occlusal force. There were 113 (17·0%) subjects with TP. The prevalence of TP was more frequent in women than in men (24·6% versus 7·5%, P<0·01). Moreover, there was a significant relationship between the presence of TP and the presence of Torus mandibularis (13·3% versus 25·9%). There was no significant relationship between the prevalence of TP and other factors; diurnal and nocturnal bruxism, occlusal force, occlusal support and temporomandibular diseases symptom. Logistic regression analysis, in which adjustment was made for age and occlusal force, revealed a significant relationship between the presence of TP and gender and the presence of torus mandibularis (TM) (P<0·001 OR=3·43, 95%CI=2·00-5·86; P<0·001, OR=2·63, 95%CI=1·64-4·24, respectively). This study suggests that genetic factors play a more significant role than factors related oromaxillofacial function in the aetiology of TP.

Factors associated with taste dissatisfaction in the elderly.

The purpose of this study was to investigate taste sensation in the elderly, and to determine relationships between subjective dissatisfaction with taste ability and factors such as age, gender and oral status among independently living elderly individuals. Participants were older adults (mean age, 66.0 +/- 4.2 years; 321 men and 319 women) voluntarily attending a Senior Citizen Educational Program supported by local government in 2003 and 2004. The questionnaire included self-assessed items on general health, dry mouth, chewing satisfaction and taste satisfaction. Respondents underwent investigation of salivary flow rate, dental status and gustatory testing using the filter-paper disc method for sweet, salty, sour and bitter. Chi-squared tests showed that the factors associated with dissatisfaction with taste ability were older age, dissatisfaction with chewing, dry mouth during eating and wearing dentures covering the entire hard palate. The sensation for each taste was not significantly related to taste satisfaction by chi-squared test. Multiple logistic regression analysis showed that dry mouth during eating, dentures covering the entire hard palate, dissatisfaction with chewing and discriminatory threshold for the sour taste were associated with dissatisfaction with taste ability. We found a significant association between subjective taste dissatisfaction and certain oral factors; hence, when patients complain about diminished taste, dentists must assess oral status as well as taste sensation.

Comparison of oral stereognosis in relation to age and the use of complete dentures.

The purpose of this study was to examine the age-related difference in oral sensory function by testing oral stereognostic ability (OSA) and to determine the effect of wearing complete dentures on OSA. Subjects were 20 dentate and 30 edentulous elderly patients free from oral symptoms and pathologies, and 30 younger dentate students as controls. The OSA tests were conducted with test pieces of 12 shaped forms. The duration time for recognition was noted and the answers were recorded using a three-point scale. anova and paired t-tests were used to examine significant differences. P-values <0.05 were considered to be statistically significant. The OSA score in older dentate participants and complete denture wearers was significantly higher than in younger dentate subjects. However, no significant difference was found in the OSA score between older dentate participants and complete denture wearers. When older edentulous subjects removed the maxillary and mandible complete dentures, the OSA score was significantly lower and the response time significantly longer than with dentures. Within the limitations of this study, an age-related difference in oral sensory function, as measured by OSA tests, was found. However, oral sensory function was not significantly different between fully dentate persons and complete denture wearers in the elderly.

Effects of light intensity and water temperature on oxygen release from roots into water lettuce rhizosphere.

The oxygen release rate into the rhizosphere by a floating aquatic plant-water lettuce-was determined under various light intensities (0.0-1.2x10(5)lx) and water temperatures (10-35 degrees C). The net specific oxygen release rate was expressed by a model equation comprising the gross oxygen release rate and the rhizosphere respiration terms. Experimental and simulated results show that the net specific oxygen release rate increased with light intensity up to the optimal value, but slight inhibition by higher light intensities was observed at 10-20 degrees C. With increased water temperature, the respiration rate became larger than the gross oxygen release rate. The maximum net specific oxygen release rate of 11.0-12.5mg-O(2)kg-wet(-1)h(-1) was obtained at the optimal condition of about 25 degrees C and 9.0x10(4)-1.1x10(5)lx. The net oxygen release rate was negligible at 35 degrees C at any light intensity because the respiration rate was much greater than the gross oxygen release rate into the rhizosphere.

The three dimensional distribution of chromium and nickel alloy welding fumes.

In the present study, the fumes generated from manual metal arc (MMA) and submerged metal arc (SMA) welding of low temperature service steel, and the chromium and nickel percentages in these fumes, were measured at various horizontal distances and vertical heights from the arc in order to obtain a three dimensional distribution. The MMA welding fume concentrations were significantly higher than the SMA welding fume concentrations. The highest fume concentration on the horizontal was shown in the fumes collected directly above the arc. The fume concentration vertically was highest at 50 cm height and reduced by half at 150 cm height. The fume concentration at 250 cm height was scarcely different from that at 150 cm height. The distribution of the chromium concentration vertically was analogous to the fume concentration, and a statistically significant difference in the chromium percentages was not found at the different heights. The nickel concentrations were not statistically significant within the welding processes, but the nickel percentages in the SMA welding fumes were statistically higher than in the MMA welding fumes. The highest nickel concentration on the horizontal was found in the fumes collected directly above the arc. The highest nickel concentration vertically showed in the fume samples collected at 50 cm height, but the greater the height the larger the nickel percentage in the fumes.

A case of primary amyloidosis confined to the small intestine.

A 60 year-old man with primary amyloidosis confined to the small intestine was reported. Multiple polyps of the small intestine were found by an upper GI series and enteroscopic polypectomy revealed massive deposition of amyloid in the lamina propria and the submucosa. No predisposing disorder or other sites of deposition were found, and the diagnosis of primary amyloidosis of the small intestine was confirmed.

[Studies on the hygiene of arc-welding. (Part 8). Effects of atmospheric conditions on the chemical composition of fumes from low hydrogen welding].

Welding fumes were generated from several kinds of low hydrogen type electrodes which changed the atmosphere with use of various gases, such air, Ar, CO2 and N2, and were collected in water with an impinger. These fumes were analyzed by X-ray refractometry and chemical analysis, and pH of their collecting water was measured. Based on these results, this paper discusses the mechanism of scattering K and Na in fumes from low hydrogen welding which are considered to be the sources of respiratory tract irritation. All sample fumes from low hydrogen welding in several atmospheric conditions contained fluorite (CaF2). The pH of water in which all sample fumes were collected remarkably elevated. Chemical composition ratios of both K2O and Na2O in all sample fumes were larger than those in coating materials. The sample fumes from welding in each of both N2 and CO2 atmosphere showed higher ratios of K2O and Na2O than those in Ar. The conclusions obtained from the discussion are as follows: The potential gradient of the arc becomes larger during welding in the atmosphere with use of N2 or CO2 because the dissociation voltage of N2 and CO2 is very low. Furthermore, fluorite (CaF2) makes the slag more fluid. Then, K and Na become easily dispersed from the arc column of low hydrogen welding.