The deglutition mechanism involves three stages: the first is the buccal pharyngeal stage, the second is the pharyngeal stage, and the third from the esophagus into the stomach.
Swallowing is affected by muscle tone, salivation, afferent and efferant function of the cranial nerves V, VII IX, X and XII providing the sensory and motor innervations to the face, lips, tongue and oral cavity. Dysphasia is often observed at the second stage in elderly people with cerebral vascular accident (CVA) and parkinsonism. The secondary effects of dysphasia may cause aspiration pneumonia. We studied the relationship of the oral function and oral hygiene to pneumonia. For the purpose of this study, 31 elders with CVA (CVA group) in a nursing home were examined and compared with 19 elders without CVA (control group). The evaluator should be aware of the resident's present status of food and liquid intake, level of oral hygiene and respiratory status. At first, we investigated the resident's history of continuous fever, cough reflexes and pneumonia. To evaluate the oral function, we examined occlusion, jaw control, tongue control, swallow (liquid-cup and solids) and oral sensory. We used a plaque for bacterial examination. The evaluation of oral hygiene proceeded according to the gingival score index and oral hygine index (OHI).
The results were as follows: 1. The CVA group experienced continuous fever more often than the control group.
2. Dysphasia was observed markedly in the CVA group.
3. The CVA group had poor chewing ability, lip closure, tongue control and oral sensitivity.
4. According to the bacterial test, pus-corpuscles were significantly found in CVA group.

View full abstract

At present, we often have to estimate the stomatognathic function of dentures based on only the patient's complaints and our own examination . We have not yet established an objective method of examining and estimating it In these circumstances, we have studied masticatory efficiency, electromyograms and biting force, as a way of examining the stomatognathic function of complete denture wearers. In this study, elderly complete denture wearers were chosen and estimated their dentures from the result of the examination of the mandibular movements and the electromyogram . Moreover, usefulness of this examination method were studied.MKG/K6-I was used for the examination, and electromyographic activities and mandibular movements were simultaneously recorded . The subjects were five elderly complete denture wearers who came to our hospital complaining of masticatory dysfunction caused by pain or the reduced retention and stability of the denture . Their opening-closing movements, gliding movements, tapping and chewing movements were examined comparing their previous denture with new denture .At the same time we had them ate some peanuts and judged their masticatory efficiency .
The examinations above, produced the following results .
1. In opening-closing and tapping movements, their new dentures indicated stability of mandibular path and intercuspal position, and increased in the velocity of vertical motion, and coordinated in electromyographic activity on both sides.
2. The examination of masticating peanuts indicated that the mandibular path from the working side to intercuspal position were stabilized and both muscle activities and masticatory rhythms were improved.
3. From the results of the masticatory test using new dentures, a recovery of the stomatognathic function was recognized.
4. In gliding movements, three subjects suggested no differences between the mandibular path of their previous denture and new denture.
5. Examination of the mandibular movements measured by MKG and the investigation of the electromyogram of masticatory muscles were applicable and useful for estimation of the stomatognathic function in elderly complete denture wearers . Further, it can be considered that examinations of both tapping movements and masticatory movements provided exact estimation of the denture function .

View full abstract

The purpose of this study is to evaluate the effects of food consistency to adult rats. Twenty male Wistar rats aged 14 weeks were used for this study and they divided into tw groups: one group (10 rats) was fed solid food (CE-2 Clea Japan Inc.) and the other group (10 rats) was fed powder food made with the some composition. The following experiments were performed at the age of 26 weeks.
1. Spatial learing and memory experiment using water maze task.
2. Spatial learning and memory experiment using a radial maze task.
No significant difference (p<0.05) was observed between the solid food group and the powder food group.These results suggested that the effect of food consistency on learning and memory ability in adult rats is minimal.

View full abstract

Morphological changes in temporomandibular joint with increasing age have been reported.
These changes could affect mandibular movements ; however, changes of mandibular movements have been never clarified. We measured mandibular movements of elderly subjects in three-dimensions to investigate changes with aging.
Ten subjects ranging from 60 to 79 years of age (old group) and 11 young subjects ranging from 19 to 24 years of age (young group) were selected. The dentition of both group subjects was either complete or nearly so, and their intercuspal positions were firm.
We investigated the paths of protrusive movement and lateral excursion at representative points; the incisal point and the condylar centers. The parameters analyzed with protrusive movement were: the sagittal inclination of the incisal path, the sagittal inclination of the condylar path, and the sagittal curvature of the condylar path. The parameters with lateral excursion were: the path length of the working side condyle, the horizontal inclination of the incisal path, the horizontal inclination of the non-working side condylar path, the horizontal curvature of the non-working side condylar path, and the sagittal inclination of the nonworking side condylar path.
The results were as follows:
1) In parameters with incisal paths, no statistical difference between the old group and the young group could be found.
2) The sagittal inclination of the condylar path during protrusive movement and that of the non-working side condylar path were gentler in the old group than in the young group.The sagittal curvature of the condylar path during protrusive movement tended to be bigger in the old group than in the young group.It is considered that these results are due to theflattening of the anterior slope of the mandibular fossa which occurs withaging.
3) In the path length of the working side condyle, the sagittal inclination and curvature of the non-working side codylar path, there was no statistical difference between two groups. These parameters are considered to relate to the condition of the lateral ligament of the temporomandibular joint. Therefore these results shows that the lateral ligament does not change even in elderly subjects, if their intercuspal positions are firm.

View full abstract

Along with the rapid growth in the proportion of senior citizens in the population, an increase in the number of senile dementia cases is expected in Japan. The incidence rate of senile dementia is generally estimated 5-7% but it is 15% among 80-84 year olds and 20% among those over 85 years old. It is expected that as the number of elderly with their own teeth increases, dentists have to be prepared to treat senile cases.
The object of the study was to understand how the dementia level influences dental practice. The subjects were 89 institutionalized elderly in a nursing home. The abilities required in dental practice were observed by dentists and the results of the observation were compared with the level of dementia judged by a psychiatrist. The possibility of dental treatment of dementia patients was investigated and the following conclusions were obtained.
(1) There was a significant correlation (correlation coefficient : 0. 636 p=0. 001) between the level of Dementia and the index of ability required in dental practice (Dental Index Score for Patient with Dementia: DISPD)
With increasing severity of dementia, the ability to be receive dental treatment.
(2) About half of the elderly with mild dementia could keep their oral area clean. But with increasing severity of dementia, the ratio of those who needed oral care increased. All the subjects with the severest dementia could not take care of themselves.
(3) Of the subjects with mild dementia, 80% could explain their chief complaints. As the severity increased, the ability to express the conditions decreased. None of the severest dementia patients could explain their chief complaints.
(4) More than 85% of the elderly except those with the severest dementia could undergo dental examination and diagnosis. The percentage for the severest dementia patient group was only 37%.
(5) As regards the ability to undergo dental treatment, only 37% of the patients in the severest dementia group were fit for such treatment, compared with more than 85% for all the other including those whodid not suffer from senile dementia.
(6) As for the subjects' attitude toward dentists and dental personnel, there was one habitually aggressive person in the severest dementia group.About 10% of senile dementia persons regardless of the degree of the disease were more of less unco-operative.
(7) Except for the severest dementia patients, it was thought possible for capable dentists with a good knowledge of senile dementia to deal with the dental problems of 80% of the patients with dementia.

View full abstract

Edentulous patients can freely purchase denture adhesive through retail outlets. However, dentists are not usually aware of what the patients think of the adhesive. We had conducted aclinical test of new denture adhesive, and evaluated its clinical effect.
The denture adhesive used for the test was a new cream type denture adhesive, and the subjects were the wearers of maxillary complete dentures. We measured the bite force of the front teeth before and after applying the denture adhesive and the result was taken as the retention strength of the adhesive. We also visually inspected the oral cavity of the subjects on the initial date and then 2 weeks and 1 month later. In addition, we distributed questionnaires to the subjects for self-evaluation of the denture adhesive before and after using it. We took all of the above into consideration to evaluate the efficacy of the product.
3 hours after applying the denture adhesive, the bite force of the front teeth was doubled from the maximum bite force without the adhesive. No side effects were reported. According to the questionnaire, the overall efficacy rate by self -evaluation was 88, 3%.
The product was found to effectively improve the stability of maxillary dentures.

View full abstract

The relation between the oral hygiene awareness and the oral health condition of elderly patients is not well known. The purpose of this study was to investigate the relation between this awareness in elderly patients and their oral health condition. The subjects were a total of 115 (none edentulous) first visited patients of over 60 years, who visited the Department of Geriatric Dentistry of Nippon Dental University. An investigation of oral hygiene awareness and an observation of the oral condition were carried out. All the information about their awareness was obtained through interviews by dental hygienists. The relationships of the awareness to oral hygiene, plaque index and the number of present teeth were evaluated.
The results were as follows ;
1.50 . 4% of subjects had received oral health instruction. More over 70 year old had received instruction than under 70 year olds . The number of present teeth was more in the subjects who had received the instruction than who had not . The oral health instruction, however, was not related to the awareness of the correct number of tooth brushings a day, the oral health condition and the loss of teeth .
2. PCR (Plaque Control Record) was 60.4% among the under 70 years olds and 81.1% among those of over 70 years olds. The oral health condition was very poor in both groups .The over 70s were poorer than the under 70s.
3. Many subjects with only a few present teeth said that there is no use complaining about the loss of teeth because of aging. The oral health condition was very poor in the subjects who have such attitude.
4. Most of the subjects brushed their teeth twice a day, The number of toothbrushings was not related to their oral health condition.
From the above, toothbrushing was not recognized by the elderly as preventing dental disease and helping treatment. It appeared that elderly peopl's oral hygiene awareness was strongly influenced by their resignation due to aging and by their experience of loss .

View full abstract