Influence of swallowing saliva repeatedly on oral moisture.

PURPOSE: The aim of this study was to examine the influence of repetitive saliva-swallowing for the level of oral moisture using an oral-moisture checking device. METHODS: Subjects were 24 healthy adults (HA) and 20 patients with oral dryness, 10 of whom had Sjögren syndrome or who had undergone radiation therapy (ODSR) and 10 who had not experienced ODSR (ODNSR). Oral moisture was measured before swallowing saliva (B), and after swallowing saliva once (F), twice (S), and three times (T). Oral moisture was measured at the lingual mucosa using an oral-moisture checking device. Statistical analysis was performed using the Friedman test. RESULTS: Oral moisture of the lingual mucosa of the HA differed significantly between B and T, and F and T, and the oral moisture level tended to be higher the more times saliva was swallowed. However, oral moisture of lingual mucosa in the ODSR was not different at the different times of measurement, but the level of oral moisture tended to be lower the more times saliva was swallowed. Oral moisture of the lingual mucosa in the ODNSR differed significantly between B and T. The trends for the changes of the oral moisture level in the ODNSR were similar to those in the HA. CONCLUSIONS: The results of this study show that swallowing saliva repeatedly could lead the increase of oral moisture in HA and ODNSR not in ODSR.

Influence of oral appliances on craniocervical posture in obstructive sleep apnea-hypopnea syndrome patients.

PURPOSE: The existence of a relationship between head posture and mandibular function has been discussed by several authors. However, the relationship between head posture and the cervical spine in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) who are using oral appliances (OAs) remains unknown. The aim of this study was to evaluate the changes in the cervical spine associated with the use of OAs in patients with OSAHS. METHODS: Fifteen patients (4 females and 11 males; mean age, 48 years) diagnosed with OSAHS were randomly selected. An OA was fabricated individually for each patient. Two lateral cephalometric radiographs were taken while the patient was sitting awake in an upright position. The first radiograph was taken in the intercuspal position and the second was taken while the subject was wearing the OA. Analyses based on the sella-nasion (SN) line were performed in the lateral cephalogram. Comparison of craniocervical angles in patients with and without the OA was performed using Wilcoxon's signed-rank test. RESULTS: Cephalometric analysis showed that the craniocervical angles (CVT-C2V and SN-C4) with OA were higher than those without OA (P<0.05). It seems that the OA caused a significant flexion of the cranium on the upper cervical spine. A significant increase in the craniocervical angle occurred in the fourth cervical segment. CONCLUSION: The changes in forward flexion of the upper cervical spine found in this study imply that changes in the craniocervical relationship should be evaluated periodically after an OA has been inserted.

[Thickness of mouthguard sheet material after vacuum forming process depending on the thickness of mouthguard sheet].

PURPOSE: Mouthguards are available to provide protection from stomatognathic injury during sports. The aim of this study was to examine the thickness of each part of mouthguard sheet depending on the thickness of mouthguard sheet material. METHODS: Cross stripes (10 x 10 mm) were printed in mouthguard sheets. We measured the thickness of each cross stripe area using a measuring-device (R). Two mouthguard sheet materials were compared. The thickness of the mouthguard sheet materials were 2 and 4 mm. The difference in the thickness of the two mouthguard sheet materials was analyzed by Wilcoxon signed-rank test and t-test. Additionally, the relationship between the elongation and the thickness of the mouthguard sheets was investigated by regression analysis. RESULTS: All parts of the sheet mounted on the cast decreased the thickness. The changes of the thickness in each part of mouthguard sheet were similar in both the 2-mm sheets and 4-mm sheets. In addition, the ratio of changes of the thickness in the part of the sheet fitted to the anterior teeth and palate on the 2-mm sheets was greater than that of the 4-mm sheets (p < 0.01). There was no statistically significant difference between the thicknesses of the sheet on the posterior teeth. The relationship between the elongation and the thickness of mouthguard sheet was modeled by quadratic equation. CONCLUSIONS: This study suggests that the ratio of changes of the thickness of the part of the sheet fitted to the anterior teeth and palate on the 2-mm sheets was greater than that of the 4-mm sheets. Furthermore the ratio of changes of the thickness of the part of the sheet fitted to the posterior teeth did not differ between the 2-mm and the 4-mm sheets.

Evaluation of the masticatory part and the habitual chewing side by wax cube and bite force measuring system (dental prescale).

PURPOSE: This study evaluated the masticatory side as well as which side was the habitual chewing side by the use of wax cubes and a bite force measuring system in normal dentate subjects (ND) and complete denture wearers (CD). METHODS: Forty two ND subjects (29 males, 13 females; mean age, 24.8 +/- 2.4 years), and 11 CD subjects (4 males, 7 females; mean age, 72.8 +/- 7.0 years) participated in the study. The test food used in this study was wax cubes to determine the masticatory side. The difference in the occlusal contact area and occlusal force between the masticatory side and the opposite side was investigated using Dental Prescale. ND was classified into 2 groups: those whose agreement on the masticatory part was high (ND-H) or low (ND-L). The distribution of the center of the occlusal balance was analyzed by Dental Prescale in ND-H, ND-L, and CD. RESULTS: The occlusal contact area and occlusal force of the masticatory side was greater than the opposite one, and the center of the occlusal balance was wide in ND-H. In ND-L and CD, the occlusal contact area and occlusal force did not differ between the masticatory side and the opposite one, and the center of the occlusal balance developed a tendency to gather in the center. CONCLUSION: The results of this study suggested that the evaluation of the masticatory side and the use of Dental Prescale were helpful in determining the habitual chewing side.

Relationship between medicine and stimulated saliva and oral moisture.

PURPOSE: The aim of this study was to investigate the relationship between medicine and stimulated saliva and oral moisture. METHODS: Fourteen patients with subjective oral dryness and 13 healthy adults were enrolled in this study. Disease, medicine, and medicines that had a side effect of oral dryness were investigated. The Saxon test was performed by chewing a piece of gauze sponge for 2 min. Oral moisture was measured at the lingual and buccal mucosa using an oral moisture checking device. Statistical analysis was performed by the Mann-Whitney U-test and Student t-test. RESULTS: Stimulated saliva and oral moisture did not differ according to the number of diseases. Oral moisture at lingual mucosa was different between a minor medicine group (0-2 types of medicine) (31.3 +/- 1.9%) and a major medicine group (>or=3 types of medicine) (29.5 +/- 2.2%) (p = 0.05). Oral moisture differed between a group not taking any medicine that had a side effect of oral dryness (31.2 +/- 1.8% at lingual mucosa and 33.8 +/- 1.4% at buccal mucosa) and a group taking such medicine (29.3 +/- 2.3% at lingual mucosa and 32.4 +/- 1.8% at buccal mucosa) (p < 0.05). CONCLUSION: The results of this study showed that oral moisture tended to decrease in the subjects who took many types of medicine or who took medicine that had a side effect of oral dryness. The medicine did not influence the amount of stimulated saliva. Therefore, it was suggested that medicine could influence the moisture of the oral mucosa.

A new method for denture identification.

Three denture marking methods were performed on specimen plates which were prepared using a heat-cured acrylic resin. The first method (LA) was to place a label into a suitable space on the specimen, and then cover it with autopolymerizing acrylic resin. The second method (DA) was to print the mark directly on the specimen, and then cover it with autopolymerizing acrylic resin. The third method (DB) was to print the mark directly on the specimen, and then cover it with bonding resin. To investigate the durability of these methods, specimens were immersed in NaOCl, denture cleanser, and coffee. Photographs of the specimens were taken and RGB values were measured. Differences in durability were analyzed by Friedman test. The RGB values were significantly different between LA and DB, but those of DA changed little. The results made it clear that DA was a more durable denture marking method than LA--which is a method generally used.

[Histological study of bone regeneration using vascular endothelial growth factor on rat mandibular bone defect].

PURPOSE: Local application of vascular endothelial growth factor (VEGF) was examined to determine whether it is effective in promoting bone regeneration. METHODS: We operated on live 6-week male SD rat mandibular bone tissue to prepare bone defects in order to attempt the guided bone regeneration (GBR) method. Laboratory animals were divided into 3 groups: the control group, the fibrin group, and the VEGF group. Both radiological observation using soft x-ray and histological observation were performed respectively on the 10th, 20th and 30th days after the operations. RESULTS: After 10 days, there was no apparent radio-photographic changes in the bone defects. However, after 20 days there were quite apparent changes, and after 30 days there were even more remarkable changes. The fibrin and VEGF groups changed more than the control group. In our histological observation, we observed rich capillary formation most notably in the VEGF group. This VEGF group also exhibited regeneration in the bone tissue. CONCLUSIONS: Histological and soft x-ray radiological observations indicated that VEGF was effective for blood vessel formation, and VEGF offers potential for bone regeneration.

[The usefulness of an oral moisture checking device (Moisture Checker for Mucus)].

PURPOSE: An oral moisture checking device is easy to use for the examination of oral dryness during clinical procedures. This study examined the usefulness of an oral moisture checking device. METHODS: The subjects in the examination of factors that influence the measured value of the oral moisture checking device were 16 sound adults (mean age 27.5). The subjects in the examination of measuring the moisture of sound adults were 32 adults (mean age 24.4). In the factors that influence the measured value of the device, the measuring pressure was examined by comparing the measured value with a trial stopper and without the stopper. The factor of sensor cover was examined by comparing the measured value before and after changing the sensor cover. The factor of device was examined by comparing the measured value using the two devices. The moisture of sound adults was measured at the lingual mucosa and buccal mucosa. RESULTS: The measured value with a trial stopper was lower by 0.2-0.3% than that without the stopper. The measured value differed before and after changing the sensor cover by 0.5-0.8%. The measured value was not different among devices. The mean value of the moisture of sound adults was 30.6+/-0.3% at the lingual mucosa, and 30.9+/-0.3% at the buccal mucosa. CONCLUSIONS: The measurement errors of the oral moisture checking device were within 1% under the condition of proper measuring pressure. Additionally, the moisture of sound adults converged toward definite values. The results of this study suggested that the oral moisture checking device is useful for the examination of xerostomia.

[The effectiveness of prosthodontic mandibular advancement for obstructive sleep apnea syndrome].

PURPOSE: This study investigated the hypothesis of a direct association between the shift of incisal point and the diameter of the oropharynx space, and nocturnal oximetry with and without prosthodontic mandibular advancement (PMA) which is one type of oral appliance used to treat obstructive sleep apnea syndrome (OSAS), and to indicate the effects of PMA. METHODS: A total of 19 patients with OSAS were subjected to finger pulse oximetry recording and lateral cephalometric radiography: with and without PMA. The distance of the oropharynx space (PNS-AS, SPAS, MAS, and IAS) and the shift of incisal point with PMA were measured. The oxygen desaturation index (ODI 4%) and the cumulative percentages of time spent at saturations below 90% (CT(90)) during sleeping were calculated. Spearman's rank correlation test was used to measure the relationship between the increase of the velopharyngeal space and the distance of the mandible. The ODI 4%, CT(90) and distance of the velopharyngeal space were compared for all subjects with and without PMA by Wilcoxon's linking test. RESULTS: There was a strong relationship between the increase of the lower part (IAS) and the distance of anterior shift of incisal point (r=0.61, p=0.01). ODI 4% and CT(90) significantly decreased (p<0.01) and the three liners of the oropharynx(SPAS, MAS, IAS) significantly increased with PMA (p<0.01). CONCLUSIONS: It was shown that prosthodontic mandibular advancement could reduce the ODI 4% and CT(90) value in patients with OSAS, by enlarging the oropharynx space.