[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: It is known that complete dentures that are stable in patients’ mouths resemble each other in peripheral shape. Moreover, it is believed that veteran dentists have similar images of how the borders of complete dentures should look. This study aimed to clarify whether prosthodontists with more than 10 years of clinical experience could effectively evaluate the posterior borders of complete dentures via photos according to their ideal image, and whether they have a set picture in their minds of how an optimal posterior border of complete dentures should look.
Materials and Methods: Twenty-four patients with complete dentures from private clinics in Niigata City were selected from survey participants to examine the relationship between oral and general health status. A dentist not involved in evaluating the dentures’ periphery photographed the polished and impression surfaces. Ten prosthodontists with more than 10 years of clinical experience evaluated the dentures’posterior borders based on the photographs. Cohen’s kappa coefficient was used to analyze variations in levels of agreement among evaluations. The concordance rate for each denture was calculated.
Results: Among all 45 combinations, nine substantially coincident matches (20%) appeared between the dentists’ evaluations based on the shape of the lower posterior border. However, with regard to the upper posterior border evaluations, only one substantially coincident match was evident. In 16.7% of both upper and lower dentures there was 100% agreement.
Conclusions: These results show that if the posterior borders of complete dentures are assessed based solely on observation, agreement among assessment ratios of experienced dentists is limited. However, the fact that 16.7% of dentures showed 100% agreement suggests the possibility that experienced dentists share a common image of how complete dentures should look.

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Purpose: This study aimed to examine whether the newly-developed crown-shaped plaster models are effective for education on the occlusal facet in complete denture practical training.
Methods: Three types of plaster models representing the bimaxillary first molar were employed for both subjective and objective assessments. One type was characterized by the natural tooth crown form (N), and the others by shapes similar to the artificial teeth of Veracia NC (NC) and Veracia SA (SA). One hundred and twenty-nine subjects (68 fourth-year students and 61 fifth-year students) attempted occlusal reshaping and answered a questionnaire to assess the validity of the prototype plaster models. The reproducibility of the relative interocclusal positional relationship in both intercuspal and eccentric positions was evaluated by measuring the distances between reference points from four directions. The efficiency of occlusal reshaping for each plaster model was evaluated by calculating the increase in the area of the occlusal facet per total weight loss in occlusal reshaping. The questionnaire results were analyzed to examine the subjective assessments of the prototype plaster models.
Results: The efficiency of occlusal reshaping for SA was significantly higher than that for NC among fifth-year students. The efficiency of occlusal reshaping for NC was significantly higher than that for SA among fourth-year students pre-reshaped SA (p<0.001). In the questionnaire, several students answered that SA was easier than NC for undergraduate students attempting occlusal reshaping.
Conclusions: These results suggest that the newly-developed crown-shaped plaster models are useful for education on the occlusal facet in comparison with conventional models using a natural crown form.

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Purpose: The aim of this retrospective study was to compare the five-year survival and complication-free rates of the teeth adjacent to partial edentulous spaces of implant-supported fixed prostheses (ISFP) and removable partial dentures (RPD).
Methods: The subjects were patients with ISFP or RPD inserted from 2003 to 2011 at the Clinic of Removable Prosthodontics, Hokkaido University Hospital. Patients who had complete dentures or an observation period of less than one year were excluded. The variables of the subjects were gender, age, prostheses, and number of remaining teeth. Variables of the adjacent teeth were the types of teeth, endodontic therapy, state of tooth restoration, and the presence of opposing teeth. The outcomes of this study were tooth extraction and tooth complications. Tooth complications were defined as tooth fracture, loss of retention, caries, periapical disease and periodontal disease. The five-year survival and complication-free rates of the adjacent teeth were estimated by Kaplan-Meier analysis. Differences of these rates for the prostheses were evaluated using the log-rank test (α=0.05).
Results: In total, 501 patients (ISFP: n=41, RPD: n=460) were selected. The five-year survival rates of the teeth adjacent to the partial edentulous spaces in the ISFP group and the RPD group were 97.5% and 90.9%, respectively. There was no significant difference between the two groups. However, the five-year complication-free rate was significantly higher in the ISFP group (89.3%) than in the RPD group (70.5%).
Conclusions: The results of this retrospective study suggested that the prognoses of the teeth adjacent to partial edentulous spaces were influenced by the prostheses.

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Patient: A 73-year-old male with moderate cerebrovascular dementia was diagnosed as dysphagia by videofluoroscopic examination. A new exercise of sucking lollipop candy for about 15 minutes was added to his usual dysphagia rehabilitation for 6 months. Changes in swallowing and other oral function, number of bacteria on his tongue surface, body weight and diet condition were investigated during the rehabilitation period. After 6 months of intervention, tongue movement was improved, maximum voluntary tongue pressure, body weight and amount of diet was increased, while the amount of food residue of bolus and the number of oral bacteria were decreased.
Discussion: In addition to the usual rehabilitation, sucking lollipop candy could be applicable and effective for preventing deterioration of oral function and oral muscles due to disuse, in spite of insufficient understanding of the rehabilitation instructions due to moderate dementia.
Conclusion: Sucking lollipop exercise could be a prospective option which improves the oral environment in addition to oral function of dementia patients.

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Patient: The patient was a 58-year-old male with the chief complaints of masticatory disorder and esthetic problems. The patient had tooth fractures and loss of posterior teeth that caused infraocclusion. The complaints were rehabilitated by a treatment denture with an increased vertical dimension. The final prostheses, having adequate occlusal vertical dimensions, were determined from the treatment denture.
Discussion: Maintenance has continued for three years and ten months, and the conditions have been stable. With focus on the vertical dimension, the use of a treatment denture to establish occlusal stabilization is recommended.
Conclusion: Infraocclusion caused by tooth fractures and loss of posterior teeth was improved by occlusal reconstruction with fixed and removable prostheses.

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Patient: The patient was a 57-year-old female who complained of inclined anterior teeth and masticatory disorder. Oral rehabilitation applying a cross-arch bridge based on the diagnostic wax-up was performed.
Discussion: Vertical stop in the premolars was constructed by a prosthesis after orthodontic treatment for the lower arch. It was necessary to observe occlusion, periodontal tissue, and the temporomandibular joint because oral rehabilitation was shortened dental arch. In case of complications, removable partial dentures for the missing teeth will be fabricated.
Conclusion: Provisional restoration to confirm the esthetics and function is important for full mouth reconstruction. This case indicates that oral rehabilitation based on provisional restoration leads to longevity and predictability.

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Patient: The patient was a 52-year-old woman with a chief complaint of mobility of the right maxillary molars and uncomfortable dentures. The diagnosis was a masticatory dysfunction caused by severe periodontitis of maxillary teeth and ill-fitting dentures in the maxilla and mandible. The remaining maxillary teeth could not be saved and were extracted. Dentures were remanufactured to establish occlusion and esthetics thereafter. However, the dentures were not acceptable to the patient because of discomfort. Therefore, an implant-supported overdenture with magnet attachments in the maxilla was eventually applied.
Discussion: Fixed dentures are not always the best option as implant-supported prostheses. From the viewpoints of occlusion and lip-support, a removable maxillary denture using implants was selected in this case.
Conclusion: The patient was satisfied with the implant-supported overdenture using magnet attachments in the maxilla.

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Patient: The patient was a 47-year-old female who visited our hospital with a chief complaint of occlusal pain in the upper left molar region. At the initial visit, examination of the oral cavity showed a root fracture of the second left maxillary molar. We extracted the tooth and replaced it with dental implants.
Discussion: The treatment was planned using a study model, diagnostic wax-up, and preoperative computed tomography (CT) to minimize the surgical invasiveness of the treatment.
Conclusion: In this case, we treated the upper free-end edentulous space with dental implants and obtained a good prognosis.

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