No abstract

Although there are numerous reports on detection of bacteria causing periodontal diseases within the oral cavity, most of these treat the oral cavity as a single entity. The objective of this study was to determine whether there was site-specificity in the detection of certain bacteria in supragingival plaque from different regions of the oral cavity. The subjects were six adults with no recognized oral problems. We examined eight regions; the labial and lingual surfaces of the upper and lower anterior teeth and the upper and lower first molars. The target bacteria included five species of bacteria that cause periodontal diseases. After professional medical tooth cleaning (PMTC), the volunteers performed no oral prophylaxis for three days. Then we collected about 1l of plaque from each of the regions by excavators. We searched for the five species of bacteria by immunoslot-blot assay and compared the results from the respective regions. We discovered that the detection rate was very small for all five bacterial species on the lingual surface of the lower anterior teeth, which is known to have good salivary clearance. On the labial surface of the upper anterior teeth, which is commonly believed to have poor salivary clearance, the detection rate was higher but there was no specificity with respect to detection rate. The regions with the highest detection rates were the buccal surface of the upper and lower molars. On the lower molars, larger populations of Porphyromonas gingivalis and Prevotella nigrescens were detected. On the upper molars, Prevotella intermedia and Prevotella melaninogenica were detected. These results suggest that there is regional specificity in the presence of periodontopathic bacteria in the mouth. it at different locations in the mouth for specific periods of time. They then determined the half-life (time needed for the potassium concentration within the agar to decrease to 1/2 of the original level) for potassium loss. The region with the shortest half-life and thus the highest salivary film velocity was the lingual surface of the lower anterior teeth, while the region with the longest half-life and thus the lowest salivary film velocity, was the labial surface of the upper anterior teeth. Weatherell et al. 3) conducted a similar survey using fluoride, while Watanabe 4) used in children the test described above, and they reported similar results. Moreover, Suzuki and Watanabe 5) simultaneously monitored pH values in three different

OBJECTIVES: The concentration of the substances eluted from the gum into saliva before and after swallowing has not almost carried out. The purpose of this study was to measure the volume of saliva before (VMAX) and after (RESID) swallowing in the mouth and was also to measure the concentration of the component (sugar) eluted from the gum chewing. METHODS: The RESID was measured by a dilution method (Lagerlof and Dawes, 1984). It was computed by measuring the potassium concentration in saliva and in the expectorated after a five-second rinse with 10 ml of water immediately following a swallow. The volume swallowed was calculated as salivary flow rate divided by the swallowing frequency, and the VMAX was estimated as the sum of RESID and the volume of saliva swallowed. Swallows were registered by placing over the larynx an electrode which was connected to an EMG. The volume of sugar contained in the gum was 74.8% as a total weight of the gum. Subjects were seven males and 13 females who were all in good health for measuring the RESID and VMAX. For each of the six participants of them, the concentration of sugar in saliva expectorated was measured by frame photometer. RESULTS: VMAX, swallowing frequency and the volume of fluid swallowed increased as comparing with the values when the salivary flow rate was unstimulated. The mean volume of sugar in expectorated saliva as a percentage of the initial weight of sugar contained during gum chewing at the first swallowing was ‫%83.5ע5.61‬ and at the 10th swallowing was ‫ע67.0‬ 0.06%. These were 3.6 times and 1.8 times of those of unstimulated saliva, respectively. flow rate peaked in the initial minutes of chewing and then fell with time towards a relatively constant value about three times greater than unstimulated flow rate. A recent study by Dawes and Kubieniec 3) also reported that when with the chewing-gums the flow rate increased initially and then, after 35-40 min, fell to similar plateau values which remained significantly higher than initial unstimulated flow rate and significantly higher than the flow rate at the corresponding time intervals when only unstimulated saliva was collected. They concluded that during prolonged chewing-gum use, both salivary flow rates and pH remained significantly above the values for

Objectives: The purpose of this study was to evaluate the effect of salivary flow rate on fluoride retention in the mouth and to measure the site-specificity of them when six healthy adults were awake and when they had been sleeping.Methods: 40 mg of NaF and 5 ml distilled water were mixed with 0.15 g of agarose which was heated until the agarose dissolved. Aliquots were pipetted into holders (diameter 4 mm, depth 1 mm) and there were bonded onto mouth guards produced from each subject. The bonding sites were on the upper anterior buccal (UAB), the upper posterial buccal (UPB), and the lower anterior lingual (LAL). When the subjects were awake, the mouth guards were fixed in the mouth and exposed to saliva for 15, 45 minutes. The agarose was taken out of the holder and put into 2 ml of distilled water for 90 minutes and the fluoride concentration were measured by a fluoride ion meter. To examine the retention of fluoride in the mouth during sleep, the mouth guards were placed before going to bed (0:00 am.) and removed at 6:30 am and the fluoride concentration measured as above. Results: The fluoride clearance from various sites in the mouth was extremely lower when subjects were asleep than when they were awake.When the subjects were awake, the half-times (the time for the initial fluoride concentration to decrease by half ) were highest in UAB and lowest in LAL. When the subjects had slept, the clearance rates of fluoride from the gel were also showed the same results of the above. Conclusion:The retention of fluoride in the mouth is affected by salivary flow rate and the fluoride concentration in the saliva was kept at high level for a long time during sleeping.

OBJECTIVE: The recovery of tooth enamel after acid etching was examined in vitro using enamel powder in order to maximize the contact surface area. METHODS: The weight of the powder decreased due to acid etching and then increased when the powder was exposed to a calcifying solution. The increase in weight was due to the formation of needle like crystals. According to thermal gravimetric analysis, the newly formed enamel layer was very stable, and was suggested to be apatite by X-ray diffraction and FT-Raman analysis. There was no distinct difference between the newly formed layer and the original tooth in terms of composite X-ray image (CaK␣ and PK␣). The new layer appeared to be a crystallized extension of the tooth enamel, as determined from SEM observations. However, the outer layer of tooth enamel was damaged by acid etching, and the crystallization had deteriorated 48 hours later when compared with that of a non-etched sample. On the other hand, we were unable to confirm the effectiveness of the recovery. From these results, the recovery of damage caused by acid etching cannot be expected when a tooth is exposed to a calcifying solution. However, the finding demonstrated that the crystallized layer was apatite. and these were analyzed by Fourier Transform Raman Spectrophotometry (FT-Raman) 8) and by X-ray diffraction and by Thermogravimetry. Materials and Methods Materials Preparation of the extracted teethFive maxillary central incisors, extracted by periodontosis and stored in distilled water, without macroscopic dental caries, morphological abnormality, or calcification abnormality on the labial surface were used. Polishing was carried out with emery abrasive paper #400, after the labial surface was cleaned by a polishing brush. Preparation of enamel powderHuman enamel powder (hereafter abbreviated as enamel powder) was prepared from 20 sound permanent teeth. The tooth surfaces were cleaned with a polishing brush. Then the dentin was ground off