To achieve greater recognition for prosthodontics in academia and among the general public as a vital health science specialty for the 21st century, and to advance this specialty's contributions to society, the Japan Prosthodontic Society has become a corporate juridical person. Today, our organization stands ready to accept the responsibility for leadership in developing initiatives to improve prosthodontic education, research, and treatment. This article examines the future prospects for our discipline in the context of current trends and prospects.

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Purpose: The aim of this study was to investigate the relationship between chewing side continuity and masticatory performance.
Methods: Twenty-two healthy subjects with normal occlusion who chewed alternately on both sides in a preliminary chewing task were selected for this study (15 males, 7 females; mean age, 25.9 years). To evaluate chewing side continuity, the subjects were asked to chew on one piece of gummy jelly for 20 seconds. This task was repeated three times, and the mean number of side-continuous strokes was calculated for each chewing side. The masticatory performance was determined by Manly's sieving method. The results obtained were analyzed for each chewing side, and the subjects were divided into two groups according to the length of chewing side continuity: the long chewing side continuity group (mean number of side-continuous strokes ≥ median) and the short chewing side continuity group (mean number of side-continuous strokes < median). The masticatory performance was compared between the two groups using the t-test, with statistical significance being established at P<0.05.
Results: Among the 44 chewing sides, the most frequently encountered number of side continuous strokes was less than 4. The mean masticatory performance was 87.0% (SD, 7.5%). The long chewing continuity group showed significantly better masticatory performance than the shorter chewing continuity group (P=0.040).
Conclusion: Our results suggest that long chewing continuity could be a measure of better masticatory performance in healthy young dentate subjects who do not have a preferred chewing side.

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Purpose: The purpose of this experiment was to investigate the possibility of objectively evaluating masticatory performance using a portable blood glucose testing device.
Methods: First, the glucose concentrations of four types of glucose solutions with known concentrations were measured using a spectrophotometer and portable blood glucose testing device. Next, 20 healthy subjects were asked to chew gummy-jelly for 20 seconds and the amount of glucose extraction was measured. The results for the two devices were compared.
Results: The glucose concentration according to the spectrophotometer was very close to the true concentration. On the other hand, the glucose concentration according to the blood glucose testing device was not close to the true value, although a statistically significant linearity was found. In regard to measurement of the amount of glucose extraction, there was a significant difference between the results obtained with the two devices. However, by using a regression line and applying the corrections to the values obtained, the values of the blood glucose testing device could be brought close to the values of the spectrophotometer (y=1.036x−2.491, r=0.994, P<0.01).
Conclusion: From these results, it was concluded that, after applying correction, a portable blood glucose testing device could measure the amount of glucose extraction from chewing gummy-jelly as accurately as a spectrophotometer.

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Purpose: The aim of the present study was to develop a new and simple method using PMB to prevent plaque colonization on denture surfaces.
Methods: PMB polymerized with MPC polymer and BMA was prepared as a coating material. Water-insoluble PMB composed of 30 mol% MPC units (PMB30), water-soluble PMB composed of 80 mol% MPC units (PMB80) and clear PMMA disks were prepared. The PMMA disks were dip-coated in 0.5 wt% PMB30 solution or 0.5 wt% PMB80 solution. To examine the PMB coatings' durability, the PMB-coated disks were immersed in distilled water. The PMB elution ratio was measured using a phosphorus analysis. To evaluate the effect of the PMB coating on Candida albicans (C. albicance) adhesion, PMB-coated and uncoated disks were cultured in a solution containing C. albicans for 48 hours. Half of the disks in each group were not washed, and the remaining disks were washed with distilled water to examine the effect of washing. All the PMMA disks were observed and photographed, and the resulting images were analyzed using imaging analysis software.
Results: In the first 48 hours, approximate 14 % of the PMB30-coating and 12 % of the PMB80-coating were eluted into the distilled water. The adhesion of C. albicans to the PMB30-coated or the PMB80-coated PMMA disks was significantly reduced in both the washed and unwashed groups, compared with the uncoated control disks.
Conclusion: PMB coating prevents the adhesion of C. albicans to PMMA.

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Purpose: This study compared oral dryness measured using an oral moisture checking device and the modified cotton method.
Methods: Oral moisture was measured at the lingual mucosa (LM) and the buccal mucosa (BM) using an oral moisture checking device in 13 healthy adults (HA) and 13 patients with oral dryness (OD). The modified cotton method was performed in the same subjects by placing cottons under and over the tongue for 30 seconds and measuring the weight of the saliva absorbed by the cotton. Differences between groups were examined using the Mann-Whitney U-test.
Results: The moisture percentage at the LM in the HA and OD groups was 30.0 ± 0.5 % and 28.6 ± 1.1 %, respectively, while the percentage at the BM was 30.3 ± 0.2 % and 29.6 ± 0.7 %, respectively. The amount of hypoglossal salivary secretion in the HA and OD groups was 0.339 ± 0.172 g and 0.036 ± 0.033 g, respectively, while the amount of salivary secretion on the tongue's surface was 0.059 ± 0.023 g and 0.011 ± 0.007 g, respectively. Both oral moisture and the amount of saliva at rest were significantly different between the HA and OD groups (P<0.05).
Conclusion: Both the oral moisture checking device and the modified cotton method were useful for measuring oral dryness. An oral moisture level of 30 % or less, less than 0.1 g of saliva collected at the hypoglossus within 30 seconds, or less than 0.02 g of saliva collected from the surface of the tongue within 30 seconds may indicate oral dryness.

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Purpose: The purpose of this study was to characterize masticatory function in patients with myotonic dystrophy (MyD) and to clarify the masticatory disturbances that might be encountered in these patients.
Methods: Eighteen patients with MyD with an average age of 54.1 years were enrolled as the subjects of this study. Factors such as activities of daily living (ADL), occlusal contact area, number of foods that were easy to chew, maximum bite force, and muscle activity in the temporal and masseter muscles during one chewing cycle were investigated, and the correlations among these factors were evaluated in these patients.
Results: The ADL score was significantly correlated with only the occlusal contact area. A significant negative correlation was observed between the muscle activity in the temporal and masseter muscles and the maximum bite force (P<0.05), as well as between the muscle activity and the number of foods that were easy to chew (P<0.01). A significant positive correlation was observed between the maximum bite force and the number of foods that were easy to chew (P<0.01), as well as between the maximum bite force and the occlusal contact area (P<0.01).
Conclusion: These results suggest that patients with MyD find only a few types of foods easy to chew because of their weak bite force, and that they compensate for the weak bite force by greatly increasing their temporal and masseter muscle activity while chewing. Also, patients with MyD with a low ADL score frequently have a small occlusal contact area.

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Purpose: Loss of molar teeth in rats has been reported to be associated with impairment of spatial memory, which may be related to hypo function of the hippocampus. However, the effects of tooth loss on the higher brain functions still remain unclear. In the present study, the glutamate levels in the hippocampus were measured as an index of the functions of the hippocampus, in order to elucidate the neurochemical changes in the brain in edentulous rats.
Methods: At the start of this study, 4-week-old male Sprague-Dawley rats were divided into 3 groups: EXT, in which all the maxillary molar teeth were extracted; ANE, in which anesthesia was administered, but no tooth extraction was performed; UNT, in which neither anesthesia was administered nor tooth extraction was performed. A guide cannula and recording electrode were then fixed in the right hippocampus of the rats at 7 weeks of age. A dialysis probe with a stimulation electrode was introduced into the guide cannula after allowing a 1-week recovery period, and the glutamate levels in the hippocampus were measured in the rats at 8 weeks of age. Tetanic stimulation (100 pulses of 0.2-ms duration at 100 Hz) was applied to the hippocampus through the stimulation electrode undermonitoring by extracellular recording via the recording electrode when the glutamate levels had stabilized. The fluctuations in the glutamate levels following the tetanic stimulation were compared among the three experimental groups using a brain microdialysis system.
Results: The extracellular glutamate concentrations within the hippocampus increased in all the 3 experimental groups following tetanic stimulation. However, the edentulous rats exhibited lower increases in the glutamate levels as compared with the sham and untreated groups.
Conclusion: Decreased afferent information from periodontal sensory receptors resulting from molar tooth loss in rats appears to cause hippocampal hypofunction. Tooth loss may thus cause impairment of memory and learning in humans.

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Purpose: The purpose of this study was to investigate the effects of different occlusal vertical dimensions (OVD) and labiolingual positions of artificial anterior teeth (LLP) on facial esthetic evaluation and to identify the related factors that affect the esthetics of the facial profile.
Methods: Ten edentulous patients were fitted with the following dentures with varying OVD (group A), and nine dentures with varying OVD and LLP (group B). Facial pictures of each of the subjects with dentures were taken from three angles (frontal, 45-degrees oblique to the right, and right lateral), and presented to 20 panelists (dentists) for esthetic evaluation. Each panelist selected two pictures at each angle that looked old and natural, respectively. A score of 2 was then assigned to the picture that was selected first and a score of 1 to the picture that was selected second; the scores across the panelists were then totaled to obtain the "old" and "natural" scores for each denture at each angle. Multiple comparisons were performed with the scores for criterion dentures serving as the control.
Results: When the OVD was −3 mm, a significant increase in the "old" score was noted. When the OVD was 0 mm and LLP was −2 mm, significant differences in both the "old" and "natural" scores were noted. When both OVD and LLP were changed, changes in the angle of photography produced different results.
Conclusion: Reduction of OVD and LLP displaced 2mm in lingual direction gave the face an unnatural and older appearance. The results of esthetic evaluation can be affected by the angle of photography.

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Purpose: Multifactorial interventions to prevent falls are relatively less effective in the elderly with dementia. We hypothesize that the primitive posture reflex associated with dental occlusion may play an important role in preventing falls in elderly persons with dementia. To demonstrate this, we compared the incidence of falls in individuals with and without dental occlusion.
Methods: This study was conducted at a special geriatric hospital for patients with severe dementia in Hiroshima, Japan. One hundred and forty-six ambulatory institutionalized elderly subjects (42 male and 104 female; mean age, 82.2 y) were divided into three groups on the basis of oral examinations: Group A, premolar and molar occlusion was maintained by natural dentition; Group B, occlusion was maintained by partial or full denture(s); and Group C, occlusion was not maintained by either natural or prosthetic teeth. Each subject was classified into either the "High Falls" (history of two or more falls during the previous one year) or "Low Falls" (history of one or no fall during the previous one year) category. In addition, a small pilot study was conducted to investigate the prevalence of falls in edentulous individuals within one year following denture delivery.
Results: During the 1-year investigation period, 41 of the 146 subjects had recurrent falls and the dental occlusion status was found to be significantly different between the "High Falls" group and the "Low Falls" group (P<0.0001). In the "High Falls" group, 10 subjects had dentures; of these, three patients were excluded because of a comatose condition or death from old age, and the remaining 7 patients experienced fewer falls during the one-year follow-up.
Conclusion: These findings suggest that dental occlusion with either natural or prosthetic teeth may play an important role in maintaining the postural reflex and preventing falls in the elderly with dementia.

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