[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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Purpose: With an increasing number of people retaining their teeth, the need for dentures has decreased slightly. However, the number of people wearing partial dentures has not changed, and appropriate denture treatments are required for the elderly. The purpose of this study was to examine the quantitative and qualitative changes in denture treatments from 1996 to 2013, using a survey of medical care activities in the public health insurance system of the Ministry of Health, Labour and Welfare in Japan.
Methods: Data on each of the medical fee points in dental practices and the cases undergoing denture treatments were extracted from a survey of medical care activities in the public health insurance system (Ministry of Health, Labour and Welfare).
The 18 years were divided into 3 periods of 6 years each, and denture treatment was analyzed according to the following categories: dentures, clasps, bars and reinforcing wires, repairs, and relines.
Results: The total number of cases involving dentures decreased after 2007. The use of dentures in patients with many or all teeth missing decreased, whereas that in patients with few teeth missing (1–8 teeth) did not decrease much. The total number of clasps used corresponded to the decrease in the number of dentures, with a little less than 3 clasps being used per plate. The use of precious metals (Au, Ag, and Pd alloy) decreased in clasps, while the use of base metals (Co-Cr) slightly increased. Temporarily, the use of bars increased in 2002, and repair cases peaked in 2003. Relining cases consisted of about 20% of the total number of new denture cases.
Conclusions: Although the number of new denture treatments has been decreasing every year, cases involving repairs and relining have not decreased much. Discontinuation of the use of reinforcing wires in the public health insurance system was associated with a transient increase in repair cases. The material of the clasps and bars has changed from precious metals with high price fluctuations to base metals. These findings are closely related to changes in the social system, technology, and public health insurance system.

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Purpose: Ceramic materials are frequently used in restorative and prosthetic treatment because of their superior esthetics, and it is important that temporary crowns are maintained in the abutment space until the final prosthetic is fitted. The objective of this study was to evaluate the properties of 10 commercial temporary cements.
Materials and Methods: Ten temporary cements were investigated: four types of resin-based cements and two types each of zinc oxide-based, carboxylate-based, and glass ionomer-based cements. The film thickness, tensile bond strength and compressive strength of these cements were measured, and the results were statistically analyzed using post-hoc Tukey multiple comparison tests.
Results and Discussion: Zinc oxide-based and glass ionomer-based cements recorded the thinnest film thickness. The carboxylate-based cements were significantly thicker than the other cements. The tensile bond strength of the resin-based cements was the highest after storage at room temperature, but the bond strength of almost all groups decreased significantly after water storage. However, the bond strength of the zinc oxide-based cements was not significantly decreased after water immersion, because of the oil component of the cement. The compressive strength of the resin-based cements was greater than that of the other cements.
Conclusion: Our findings suggested that the strength of temporary cements affected the bond strength.

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Purpose: The purpose of this study was to reproduce three-dimensional chewing movements and the change of occlusal contact points by software.
Materials and Methods: The study model was converted into the software as STL data from a CAD scanner. In addition, we recorded XML data of the mandibular border movement, opening and closing movements, and chewing movements using a six-degree-of-freedom jaw tracking device (ARCUS digma2, KaVo, Biberach, Germany). The XML data was converted to STL data, and we reproduced the three-dimensional chewing movements and occlusal contact points by the software.
Discussion: Using the functional analysis program, it is possible to reproduce the border movements, opening and closing movements, and chewing movements in three dimensions. We could also observe the change of occlusal contact points in the chewing movements. We suggest that occlusal interference could be found or the temporo-mandibular joint could be examined in the future by using the software to analyze three-dimensional jaw movements.
Conclusions: We succeeded in observing three-dimensional jaw movements from every angle by the software. In addition, the changes of occlusal contact points in chewing movements were reproduced.

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Patient: A 66-year-old male visited our hospital with a chief complaint of occlusal discomfort. He had subjective and objective symptoms caused by severe attrition of teeth. We reconstructed the occlusion with prosthetic treatment, performed occlusal reconstruction and evaluation, and then performed crown restoration of the mandibular teeth. He wore an occlusal splint so that there was clenching and received periodical medical examination every six months. Four years have passed since the treatment without incident.
Discussion: Occlusal discomfort seems to have disappeared, suggesting that we established cuspid protected occlusion and proper occlusal vertical dimension and removed occlusal interference of the second molar for lateral movement.
Conclusion: In this case with a complaint of occlusal discomfort due to severe attrition of the full mouth, the occlusal discomfort and other symptoms disappeared by oral rehabilitation. As a result, the patient obtained satisfaction and health.

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Patient: The patient, a 55-year-old woman, complained of bleeding and pus discharge from the maxillary anterior gingiva. The patient was diagnosed as having severe generalized periodontitis with a defective prosthesis. Periodontal therapy and occlusal improvement using provisional prostheses were performed together. As the final prostheses, a cross-arch bridge in the maxilla and bridges in the mandible were placed. Thereafter, she has remained satisfied without the previous complaints.
Discussions: Accurate transfer of the crown shape from the provisional prostheses to the final ones and subsequent maintenance accounted for the good prognosis.
Conclusion: Appropriate periodontal and occlusal therapy for this periodontally compromised patient has led to a good course for more than 5 years since the final restoration.

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Patient: The patient was a 61-year-old woman with the complaint of dysmasesis by fracture of dentures. She had only one occlusal contact in the right canine region, and was diagnosed as infraocclusion by occlusal analysis. As previous treatments, bite raising and occlusal reconstruction had been done with treatment dentures. Guide planes were made on every remaining tooth to increase the grip force of the dentures, then the removable partial dentures were inserted.
Discussion: In this case, an appropriate occlusal vertical dimension was set by several measurement methods. By making guide planes on every remaining tooth, the grip force of the dentures was increased and an excellent result of treatment was achieved despite the non-vertical stop occlusion.
Conclusion: In the present case, an excellent result was achieved by bite raising and occlusal reconstruction followed by fabricating dentures with enough grip force.

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Patient: A 43-year-old male patient complained of articulation disorders after the placement of an adhesion bridge to restore maxillary anterior missing teeth. Since severe bone resorption was detected by X-ray CT in the edentulous region, implant prosthetic treatment was performed following autogenous bone grafting. Finally, the edentulous space was restored with an implant-supported fixed prosthesis.
Discussion: Symmetry of the oral cavity proper, consisting of alveolar ridge form and palatal wall of the dental arch, is closely related to articulation function, therefore abnormalities of anterior palatal form can cause articulation disorders. In this case, the palatal wall of the superstructure was fabricated to be as symmetrical as possible, taking tongue function into consideration. Since the superstructure was fixed with cementation, improvement of articulation and comfort of the tongue were obtained.
Conclusion: Improvement of articulation was achieved by symmetrical restoration of the oral cavity proper.

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