The authors would like to introduce the invention, derived from the research on denture plaque, applied to a wide variety of items.

Firstly, we found L. rhamnosus L8020, as one of the normal strains of bacteria in the oral cavity and have shown to have inhibitory activity against a broad spectrum of bacteria causing dental caries and periodontal disease, in addition to oral Candida. Based upon the patents on L. rhamnosus L8020, several products incorporated with L8020, like mouthwash, dentifrice, tablets and chocolate, in addition to yoghurt, have been commercialized.

Secondly, we developed the organosilicon quaternary ammonium salts [3-(triethoxysilyl) - propyldimethyl- octadecyl ammonium chloride (Etak), a coupling agent with disinfectant. It has broad spectrum antimicrobial activity against both Gram-positive and –negative bacteria, fungi and yeasts, in addition to envelope virus, like influenza and corona virus. This compound binds chemically to a variety substrates, making it a nonleachable antibacterial and antiviral agent. Its bounded antimicrobial activity has had a variety of applications by binding to fibers, fabric, carpet, sock manufactures (to control odor-causing bacteria), and metal surfaces. The effects will be contributed to the suppression of a variety of infectious diseases, including flu and covid-19. Mikihouse, Dinos, AOKI, Esai company has been commercialized a variety of items, based upon our patents.

This paper described the examples that intellectual property based upon innovations from prosthodontic research have been utilized by general companies, and yielded the living ware.

As you know, there are 4,620,000 patients with dementia in Japan by estimate. Now, we live in the super-aging society that any country has never experienced before. In the current situation where there are no disease modifiers even for Alzheimer’s disease, what medical workers including medical doctors, dentists, pharmaceutical chemists and others do for the nation is more disease enlightenment and preemptively preventive intervention. Such activities are prescribed by the Comprehensive Strategy to Accelerate Dementia Measures called “New Orange Plan” as Japanese national policy. From the prevention to the therapeutics, many investigations and studies for dementia are performed in each clinical department concerned. Needless to say, many suggestive clinical knowledge in an oral cavity region are reported from dentists, however these clinical information cannot become a common sense in researchers and clinicians for dementia.

Why is such a phenomenon occurred? One of the cause of the problem is a study design. For example, in spite of the preventive medical study for the mild cognitive impairment (MCI), it is an essential mistake by using Mini-Mental State Examination (MMSE) of neuropsychiatric cognitive examination. MMSE is not a screening tool for MCI but it for dementia.

I will make “a common language” a Key word and consider its reason and a solution for it in this article.

As a term indicating the state that the oral function of older adults decreased, both of oral frailty and oral hypofunction are used. Oral hypofunction is a disease whereas oral frailty expresses the state that an oral function decreases. It is reported that decreasing oral function is associated with dementia and decreasing cognitive function. Because the treatment of dementia is not yet established, we should consider the prevention of mild cognitive impairment by the management of oral function in older adults. In this report, we introduce recent reports including our researches about the association between cognitive function and oral function.

The number of patients with dementia is increasing not only in Japan but also worldwide. Recently, the importance of prevention in daily life rather than treatment is emphasized for dementia. As prevention of dementia, various preventive methods such as improvement of lifestyle habits such as appropriate exercise and diet therapy have been introduced, and mastication is also expected as one of them.

Although there are many reports supporting the relationship between mastication and dementia / cognitive function based on previous research reviews, the underlying mechanism has not been elucidated. In order to understand the mechanism in the future, it is necessary to conduct comprehensive research and research based on the research system of medical and dental cooperation, and the progress of neuroimaging research may greatly contribute.

Objectives: This article describes the examination and management of seven items of oral hypofunction, including tests for chewing ability, and introduces measures for its efficient implementation.

Introduction process: In April 2016, “tests for chewing ability for dentures” was introduced to medical insurance, and since April 2018, it has been possible to conduct a test for masticatory efficiency alone and an occlusal pressure test has been added. Test and management of “Oral hypofunction” was introduced in April 2018.

Spread of the test: The tests for chewing ability for dentures have not been performed on 1% or less of the indicated cases even after more than 3 years since its introduction. Test for oral hypofunction was also very limited due to the time required and other reasons.

For effective implementation: It will be necessary to set standard values for the tests for chewing ability for dentures. For oral hypofunction, it may be necessary to set the order of examinations, use patient explanation sheets, and revise insurance rules. It is our responsibility to contribute to the oral health of the people by utilizing these tests.

Purpose: The influence of an anodized titanium custom abutment on the color of highly translucent zirconia used for the superstructure was investigated.

Methods: Using a columnar titanium alloy of 10 mm diameter and 10 mm height, three types of sample, untreated (gray) and anodized (gold and pink) samples, were prepared as experimental groups. For the control group, resin samples were prepared. Highly translucent zirconia of 0.5 mm thickness was used for the samples, and two types of cement paste, those with universal and opaque colors, were used. The paste was inter-positioned between the abutment and zirconia, colorimetric tests (L*, a*, b* values) were performed using a non-contact type dental spectrophotometer, and differences in color (ΔE) on comparison with the control group were calculated.

Results: When the universal and opaque colors were used, the color differences (ΔE) were 11.61 and 5.81, respectively, showing a significant difference between the cements (P < 0.05). In addition, when the pink titanium sample was used, the color difference of the opaque color (ΔE) was 4.21, being the minimum value. On the other hand, the color (hue/chroma) index when using the opaque color, a* value, showed diverse changes, such as −0.66 (tended to be green) when the gold color was used.

Conclusion: These findings suggest that the use of anodized titanium and opaque color cement reduces color changes of highly translucent zirconia. In addition, the variation of a* value suggests the necessity of color adjustment, such as adjustment of stain, because the color of the abutment may influence the color of highly translucent zirconia.

Purpose: The study aimed to quantitatively and morphologically evaluate the gothic arch (following GoA) and tapping point (following TP) records at the time of new denture production, and to statistically analyze the number of adjustments of the new dentures and clarify the relationship.

Methods: Thirty-four records obtained by the GoA tracing method with tapping method were examined. Quantitative and morphological evaluations were conducted using the newly obtained GoA score. The results were divided into four groups by distance among the apex (following Ap)/TP and were statistically analyzed.

Results:

① Group A (0–0.8 mm) accounted for 32.4% (11 patients), group B (0.9–1.6 mm) 35.3% (12 patients), group C (1.7 mm) 23.5% (8 patients), and group D (TP only) 8.8% (3 patients). Ap and TP matched in 11.8% (in group A).

② There was no statistical difference in the front momentum or lateral momentum.

③ Within each group, there was no statistical difference in the spread angle from Ap.

④ The spread angle from TP increased with increasing Ap/TP distance.

⑤ The GoA score increased with increasing Ap/TP distance.

⑥ TP converged in 19 of 34 cases, but not in 15 cases. Compared with the cases where TP converged, the Ap/TP distance and GoA scores were significantly greater in cases where TP did not converge.

⑦ Regarding the number of denture adjustments, there was a statistically significant difference from group B, to group A and group C.

⑧ There was no relationship between the number of new denture adjustments and the convergence of TP.

Conclusion: Quantitative and morphological evaluations were performed on GoA and TP records, and the relationship between the number of denture adjustments and the convergence of TP was evaluated. When the distance among Ap/TP increased, there was no change in the functional limit of the mandibular movement from Ap. On the other hand, the movement from TP used the area of intermediate movement, therefore, the statistical variance increased. It was also found that the GoA score increased as the distance among Ap/TP increased, proving dysfunction of the mandibular movement. Regarding the number of denture adjustments, there was a statistically significant difference for group B, but clinically, there were only small differences with other groups. If the Ap/TP distance or GoA score increases, there may be an organic change in the temporomandibular joint or an inconsistency in the neuromuscular mechanism. However, the GoA tracing method with tapping method can diagnose whether or not the TP is appropriate for the mandibular position for the dentures.

Patient: A 63-year-old female patient presented with gingival swelling considered to be caused by metal allergy in the mandibular left posterior teeth. As a result of pathological tissue examination and patch tests, the patient was diagnosed with oral lichen planus due to dental metal allergy to Au, Pd and Sn. In this case, the metal materials were removed and replaced with provisional restorations, and the improvement of symptoms was evaluated thereafter. Monolithic zirconia single crowns were placed on the maxillary right and mandibular left posterior teeth.

Discussion: The periodontal tissues and occlusal function have remained in good condition for more than five years. No allergic reactions have been observed.

Conclusion: It was demonstrated that the removal of dental metal materials is effective for treating allergic symptoms in patients sensitized to dental metal materials. This case of lichen planus caused by dental metal allergy was relieved by replacing monolithic zirconia restorations.

Patient: A 74-year-old male complained of difficulty with eating properly due to instability of his complete dentures. New complete dentures were fabricated with the closed mouth impression technique. However, pain in the lower incisal area continued, so a dynamic impression technique was performed and the area was relined by the indirect method.

Discussion: A possible cause of overpressure in the lower anterior area may have been that the patient’s occlusal force was not appropriate at the time of taking the closed impression, or that impression pressure was likely to be applied to the anterior area.

Conclusion: The overpressure generated at the final impression was corrected by the dynamic impression technique to finally achieve the patient’s satisfaction and recovery of masticatory function.

Patient: A 59-year-old male patient complained of an unstable denture, masticatory dysfunction, and poor esthetics. Based on the clinical findings, the instability of the denture and esthetic disturbance of the lower anterior teeth were attributed to reduction of the occlusal vertical dimension caused by attrition of the teeth. Therefore, a fixed partial denture was chosen for the maxillary anterior teeth in order to reduce the overload on the upper-right second molar and retain the anterior guidance and physiological occlusion after bite-raising. Finally, the patient’s complaints improved after full mouth reconstruction.

Discussion: The patient’s satisfaction was improved by fabricating a fixed partial denture for the maxilla, instead of a removable partial denture that gave rise to denture fracture and instability.

Conclusion: It is suggested that long-term stability of the prosthesis was obtained by correctly diagnosing tooth attrition and providing treatment with better prognosis.

Patient: A 39-year-old male patient underwent subtotal glossectomy, radical neck dissection on the right side, and reconstruction using a forearm flap under the clinical diagnosis of recurrent tongue carcinoma. The patient’s chief complaints were speech disorder and swallowing disorder due to the glossectomy and dissection. Tongue pressure production was evaluated before, during and after the fabrication of a palatal augmentation prosthesis (PAP) and mandibular partial denture with extended saddle.

Discussion: The PAP and mandibular partial denture with extended saddle improved speech intelligibility and swallowing ability.

Conclusion: For patients with severe disorder in tongue movement, speech intelligibility and swallowing ability can be improved by securing tongue-palate contact and optimizing the oral cavity volume.

Patient: The patient was a 76-year-old woman with severe dry mouth due to Sjögren’s syndrome. She complained of instability of her dentures when eating and talking. After correction of the occlusal plane and denture formation using treatment dentures, a maxillary complete denture and a mandibular cone crown telescope denture were inserted.

Discussion: In this case, the fitting, shape of the polished surface, and occlusion of the prostheses were improved to ensure denture stability with function by the treatment denture. The patient was satisfied with the recommendation to use oral moisturizers for the severe dry mouth.

Conclusion: The result in this case suggests that appropriate denture formation and care of dry mouth could improve oral functions and satisfaction in patients with severe dry mouth.

Patient: The patient was a 68-year-old man who had mastication disorder and esthetic failure after resection of mandibular gingival carcinoma with surgical reconstruction. He had multiple tooth loss, and presented restricted mandibular movement and deviation of mandibular position to the right associated with surgical reconstruction. Comprehensive prosthetic treatment was planned by using treatment dentures.

Discussion: It was considered that a satisfactory outcome and good prognosis of the final denture were achieved by monitoring the oral function and associated changes over time using treatment dentures.

Conclusion: Advance comprehensive planning of the prosthetic treatment based on preliminary treatment dentures in this patient, who had undergone mandibular gingival carcinoma resection with surgical reconstruction, resulted in a favorable outcome.

Patient: A 52-year-old male with difficulty in chewing was referred by an oral surgeon for postoperative mandibular denture preparation. His mandible was reconstructed with peroneal free flap following resection of ossifying fibroma. Alveoloplasty was then performed as preprosthetic treatment and a mandibular interim denture was inserted and adjusted. After wound healing, a mandibular telescopic crown-retained denture was inserted.

Discussion: In this case, it was considered necessary to provide rigid support for the mandibular denture to ensure it would withstand forces during use. The mandibular denture was likely made stable by the alveoloplasty preventing its mobility in conjunction with compressibility of the flap.

Conclusion: It is suggested that good results may be obtained by applying the concept of rigid support.

Patient: The patient was an 81-year-old female who exhibited difficulty in performing shigin and chewing due to the instability and poor retention of dentures. The occlusal plane was irregular because of elongated maxillary teeth, and both maxillary and mandibular dentures were ill-fitting. A cone crown telescope was inserted into the maxilla, and a resin-base complete denture was inserted into the mandible after confirming retention and stability of the treatment dentures.

Discussion: Alteration and confirmation of the denture form and mandibular position using treatment dentures before placing the final dentures improved the speech disorder and masticatory disturbance.

Conclusion: The use of treatment dentures for patients with a markedly resorbed alveolar ridge may improve the therapeutic effects of the final dentures.

Patient: The patient was a 79-year-old female who visited our hospital with the chief complaints of esthetic problems and masticatory disorder. At the first examination, the patient had no occlusal-supporting area, so a decrease of occlusal vertical dimension was suspected. The vertical dimension was increased by using treatment dentures, and finally a fixed prosthesis and removable partial dentures were inserted.

Discussion: In this case, a provisional restoration was attached after recovering the vertical dimension with the treatment dentures. When transitioning to the final prosthesis, it is considered that the masticatory function at the attached provisional restoration could be reproduced by using the face bow record and check bite method.

Conclusion: Decrease of occlusal vertical dimension and loss of occlusal-supporting area were improved by using fixed and removable prostheses with appropriate vertical dimension, and good results were obtained.