Annals of Japan Prosthodontic Society
Online ISSN : 1883-6860
Print ISSN : 1883-4426
ISSN-L : 1883-4426
Current issue
July 2020
Showing 1-16 articles out of 16 articles from the selected issue
Preface
Erratum
Invited Articles
  • Hirofumi Yatani
    Type: Invited Article
    2020 Volume 12 Issue 3 Pages 209-224
    Published: 2020
    Released: August 13, 2020
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    Objectives: The objective of this systematic literature review was to assess the long-term clinical outcome of all-ceramic cantilever bridges.

    Methods: An electronic PubMed search supplemented by manual searching was conducted to identify randomized controlled trials as well as prospective and retrospective cohort studies on the all-ceramic cantilever bridges with a minimum 2-year follow-up. The search provided 104 studies with abstracts. A full-text analysis was performed for 15 studies that met the inclusion criteria. Of these 15 studies, 5 studies were excluded because they were follow-up studies of the same study cohort.

    Results: The results obtained are as follows: 1) Survival and success rates were considered in 10 different cohorts of 302 patients; 2) Cantilever bridges as a prosthetic method for minor tooth loss that embodies MI concept, especially resin-bonded cantilever bridges, have higher survival and success rates, compared to two-retainer resin-bonded bridges; 3) Case selection is an important factor for successful cantilever bridge. The upper lateral incisor, the upper central incisor, the lower incisor, and the upper and lower bicuspids are suitable for the pontic location of the bridge. It is desirable that the tooth loss is single and the abutment tooth is vital; 4) As a material to be used, high density sintered zirconia has been recently replacing glass ceramics, and is considered to be the most suitable material; 5) The incidence of complications is generally low. Especially the frequency of biological complications is extremely low, and most of them are technical complications such as debonding; 6) Strict application of the bonding technique established in two retainer-type resin bonded bridges is mandatory for the success of all-ceramic cantilever bridges.

    Conclusion: The survival and success rates of all-ceramic cantilever bridges, especially resin bonded cantilever bridges, are very high. All-ceramic cantilever resin-bonded bridges have many advantages over the conventional two-retainer bridge and present a promising treatment alternative to cantilever resin-bonded bridges using a metal frame.

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Position Paper
Invited Articles
  • Yasuo Morimoto, Hiroto Izumi, Taisuke Tomonaga, Chinatsu Nishida
    Type: Invited Article
    2020 Volume 12 Issue 3 Pages 227-233
    Published: 2020
    Released: August 13, 2020
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    Various chemical substances are handled among the workplace of dental technicians, and highly harmful chemical substances such as cobalt, chromium, cristobalite and indium have been used. Since occupational health management of indium handling work has already been issued as a notification from the government, occupational health management are introduced separately from indium and general chemicals handling workplace. The main measures in the occupational health management of general chemicals are to perform concentration measurement of the chemicals, to prepare local exhaust ventilation, to use appropriate dust or gas mask, to conduct special medical examinations for chemicals include pneumoconiosis. The work environment of dental technicians is not listed as a dust workplace in Ordinance on Prevention of Hazards due to Dust Ministry of Labour Ordinance. However it is necessary to perform sufficiently the occupational health management because of case reports and epidemiological studies to induce the pneumoconiosis in the workplace of dental technicians.

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  • Hiroaki Takeuchi, Mika Terada, Kazuko Kobayashi, Nobuhiro Hanada
    Type: Invited Article
    2020 Volume 12 Issue 3 Pages 234-242
    Published: 2020
    Released: August 13, 2020
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    Insufficient masticatory function causes an increase in carbohydrate intake while decreasing the intake of foods with a low Glycemic Index (GI) and high in protein, dietary fiber, antioxidants, vitamins and minerals. Continuous status of high carbohydrate and malnutrition may increase the risk of developing metabolic syndrome, frailty, and Non-Communicable Diseases (NCDs). Prosthodontic treatment is a medical technique which not only significantly restores the masticatory disfunction, but also contributes to reducing the risk of systemic diseases, improving body composition, and promoting good health. We believe that prosthodontic treatment, the purpose of which had been directed only toward esthetic recovery and oral health so far, should be evaluated and paid attention to in the fields of healthy lifespan and prevention of onset and deterioration of NCDs more than ever before.

    This paper describes some concrete approaches for health guidance before and after prosthodontic treatment, setting the ultimate goal of the treatment to items related to health promotion. Although our approaches are still in the process of systematization, the dentistry should henceforth be asked for a new medical care system by adding a function of checking up for general health to the control of oral diseases, and should play an important role in extending healthy lifespan.

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Review
  • Masako Nagasawa, Hiroshi Kono, Masakazu Okubo, Nami Akiba, Atsushi Min ...
    Type: review-article
    2020 Volume 12 Issue 3 Pages 243-256
    Published: 2020
    Released: August 13, 2020
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    One of the major purposes of dental education is to acquire clinical ability. Dentists should fulfill the patients’ requirements by flexibly applying these clinical ability based on proper knowledge. Especially, prosthodontic treatment requires not only the ability of prosthodontic diagnosis, but also high technical skills. In 2020, a skill examination, as part of the post-clinical clerkship clinical performance examination (Post-CC CPX), will be introduced officially in Japan. This movement is in response to the recent social demand for assuring the clinical ability of dental students upon graduation because the environment of students’ clinical training has dramatically changed and become more complicated with the super-aging of society. Moreover, the Japan Prosthodontic Society introduced a technical skills competition for dental students this year. In this paper, we discuss clear outcomes, methods and assessments of technical training in prosthodontics. As specialists of prosthodontics, we should reconsider how technical training should be as members of an educational institute whose mission is to train high-quality dental students.

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Case Repor
  • Yu Yonezawa, Takuya Kobayashi, Saori Aki, Yutaro Oyamada, Syouta Fukaz ...
    Type: case-report
    2020 Volume 12 Issue 3 Pages 257-263
    Published: 2020
    Released: August 13, 2020
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    Patient: In recent years, the application of information technology to clinical dentistry has progressed, and even in the field of dentures, it has become possible to make dentures using CAD/CAM technology. However, digital technology cannot be applied to all denture manufacturing processes, including clinical procedures and laboratory operations.

    We report on the immediate production of a dental prosthesis by taking an optical impression using an intraoral scanner in a case where the conventional precise impression could not be obtained due to the progress of periodontal disease. The patient was a 52-year-old woman. She was scheduled to undergo extraction of a large number of teeth due to severe periodontitis. When the source of infection associated with tooth extraction was removed, she wanted a treatment that would not cause esthetic or chewing problems. We obtained digital data, erased the teeth to be extracted and arranged the artificial teeth on the CAD software, output the designed data as STL data, immediately fabricated the denture, and mounted it.

    Discussion: This new method for denture fabrication provides safe dental care without esthetic disorders for patients with advanced periodontal disease.

    Conclusions: Dentures can be immediately produced using CAD/CAM technology based on optical impression in cases where an accurate impression cannot be obtained by the conventional method.

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Original Articles
  • Yuta Yamazaki, Atsushi Kawamura, Makiko Takashima, Yoshiaki Arai
    Type: research-article
    2020 Volume 12 Issue 3 Pages 264-271
    Published: 2020
    Released: August 13, 2020
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    Purpose: Previous clinical studies have indicated that the loss of retention between post and tooth is a major cause of failure in the restoration of endodontically treated teeth. Since bubble-like defects were found in the cement layer of the debonded post, we hypothesized that this cement defect decreases the adhesive strength. The purpose of this study was to evaluate if the technique used to insert resin cement influences the presence of bubbles and the push-out bond strength.

    Methods: The root canal of a transparent resin block and bovine tooth were parallel-wall drilled with a Peeso Reamer to achieve a post length of 10 mm. Prefabricated metal posts were cemented using self-adhesive resin cement, for nine combinations of three tools and three cement application sites. The resin block was scanned with a digital camera, then image analysis software was used to calculate the percentage of bubbles in the cement layer. Bovine teeth were sectioned into five 1-mm thick slices for the push-out bond strength test.

    Results: The bubbles were concentrated at the apical side for all methods. When we used the plastic needle to apply cement to the post and root canal, the bubble mixture rate was significantly lower than that of the other methods. Using the brush resulted in a significant decrease in the push-out bond strength at the apical side, whereas there was no significant difference in the push-out bond strength between the sites with other tools.

    Conclusions: It is considered that there is less adherence at the site of air bubbles, and therefore a decrease in the adhesive strength. We conclude that it is important to use a tool that reaches the deepest part of the prepared root canal to reduce the air bubble mixture rate and to obtain the highest adhesive strength.

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  • Keishi Ohta, Kaoru Koide, Toshihide Sato, Mami Ishii
    Type: research-article
    2020 Volume 12 Issue 3 Pages 272-279
    Published: 2020
    Released: August 13, 2020
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    Purpose: The objectives of this study were to determine how changes in body and head posture during dental treatment affect condylar position, and to develop a set of standards for the patient’s posture.

    Methods: Condylar position was investigated in eight subjects with normal occlusion and not suffering any stomatognathic dysfunction. This was done by measuring deviation in the anteroposterior direction and vertical direction, and an anterior jig was attached in all eight subjects. The measurement conditions were four kinds of head position (backward 10 degrees, forward 0, 10, 20 degrees from the reference position) and four kinds of body position (backward 50, 60, 70, 80 degrees from the reference position) while in the supine position and tapping on the incisal point. The measuring equipment was a jaw-tracking device, which measured the jaw three-dimensionally with six degrees of freedom. The Frankfurt plane was adopted as the reference plane for the jaw-tracking device, and Beyron’s point was used as the measurement point. The anteroposterior direction and the vertical direction were determined.

    Results: A significant difference in anteroposterior direction was recognized between head positions of 0 degree and 10 degrees forward, 0 degree and 20 degrees forward, 10 degrees backwards and 20 degrees forward. A significant difference in vertical direction was recognized between head positions of 10 degrees forward and 20 degrees, 0 degree and 20 degrees forward, 10 degree backward, 10 degrees forward and 20 degrees. Changes in posture had little effect on condylar position.

    Conclusions: The results of the present study suggest that the condylar position may be affected by the patient’s head and body posture. In conclusion, careful adjustment of the patient’s head and body position is needed when recording the occlusal registration or performing occlusal adjustment.

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Case Reports (Specialist)
  • Hidemichi Kihara
    Type: case-report
    2020 Volume 12 Issue 3 Pages 280-283
    Published: 2020
    Released: August 13, 2020
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    Patient: A 19-year-old male patient visited for lower anterior teeth treatment with dental implants. He had fallen from a high place onto his face, and had suffered a wide range of crest defects in the mandibular anterior region due to a complex fracture of the mandible. An iliac bone graft was performed from the inferior border of the mandible, then a superstructure for dental implants and fixed prosthesis for natural teeth were installed.

    Discussion: A functional and esthetic dental implant prosthesis could be provided for a wide range of bone defects by combining iliac bone grafting and free gingival grafting for the complex fracture of the mandible.

    Conclusion: Currently, no problems with the soft and hard tissue surrounding the implant are observed. It is necessary to monitor the bone resorption of the transplanted bone.

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  • Masaki Kakudo
    Type: case-report
    2020 Volume 12 Issue 3 Pages 284-287
    Published: 2020
    Released: August 13, 2020
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    Patient: The patient was a 66-year-old woman with the chief complaint of poor esthetics of the upper teeth, which she wanted to be replaced. The patient was diagnosed as having an esthetic disorder due to an inadequate fixed partial denture on the maxillary anterior teeth and a functional disorder due to missing molars. Occlusal reconstruction with hybrid resin facing prostheses and removable partial dentures was performed.

    Discussion: The vertical mandibular position was established at the crown and bridge prostheses, and the final prostheses were mainly tooth-supported. The design of the retainers of the removable partial dentures was also taken into consideration to ensure good esthetics.

    Conclusion: Occlusal reconstruction and good esthetics were obtained with hybrid resin facing prostheses and removable partial dentures.

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  • Shunta Miwa
    Type: case-report
    2020 Volume 12 Issue 3 Pages 288-291
    Published: 2020
    Released: August 13, 2020
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    Patient: A 66-year-old male complained of ridge pain during compromised periodontal maintenance. Tooth mobility at the upper right and lower left molar region was observed and the upper left and lower right edentulous ridges opposing the remaining teeth were severely resorbed. The patient was diagnosed with masticatory disturbance due to chronic periodontal disease and incompatibility of dentures. After agreeing on mouth preparation and the production of removable dentures, the mobile teeth were extracted and the lower remaining teeth underwent root canal treatment, and were then covered by a magnetic attachment and root cap. Upper and lower complete dentures were made with metal plates.

    Discussion: It is considered that mechanical stability was improved by decreasing the pressurization factors and correcting the occlusal plane.

    Conclusion: The overdenture was an effective treatment option for this case of non-vertical stop occlusion in terms of maintaining occlusal balance.

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  • Yusuke Mihara
    Type: case-report
    2020 Volume 12 Issue 3 Pages 292-295
    Published: 2020
    Released: August 13, 2020
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    Patient: The patient was a 69-year-old man who complained of pain and discomfort when eating. His maxillary complete denture showed attrition, while his mandibular complete denture showed remarkable defects in the shape of the denture base, fitness, occlusion, and placement position of artificial teeth. A temporary denture was made for only the mandibular denture with many problems, while for the maxillary denture the occlusal surface of the artificial tooth was repaired. After making the temporary denture, maxillary and mandibular dentures were made using impressions with the closed mouth position method.

    Discussion: Periodic examinations are still being carried out, with good findings. The early functional recovery and establishment of a good relationship with the patient seem to have improved the patient’s satisfaction with the final dentures.

    Conclusion: By making the mandibular denture and repairing the maxillary denture, the patient’s function was restored early.

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  • Yosuke Akiba
    Type: case-report
    2020 Volume 12 Issue 3 Pages 296-299
    Published: 2020
    Released: August 13, 2020
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    Patient: A 52-year-old female complained of masticatory disorder caused by missing mandibular molars and esthetic disorder because of malocclusion of the mandibular anterior teeth. After orthodontic treatment, non-vertical stop occlusion and low occlusal vertical dimension were observed. Removable partial dentures and provisional bridges were used to restore the mandibular position. After achieving occlusal support by implants, a porcelain fused to metal crown was made in accordance with the custom incisal table to provide relevant anterior guidance, and occlusal support was acquired by dental implants. Anterior guidance was then reconstructed with the custom incisal table and a porcelain fused to metal crown was fabricated.

    Discussion: The risk of collapse of occlusion caused by non-vertical stop occlusion was reduced by mandible repositioning and occlusal support by implants.

    Conclusion: The use of implant prostheses improved the occlusal relationship, esthetics and patient’s oral health-related quality of life.

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  • Mika Honda
    Type: case-report
    2020 Volume 12 Issue 3 Pages 300-303
    Published: 2020
    Released: August 13, 2020
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    Patient: The patient was a 54-year-old female with dental phobia, complaints of esthetic dissatisfaction and masticatory dysfunction. A treatment denture was placed after tooth extraction. The definitive denture with non-metal clasp denture was placed after the treatment denture was placed. The prognosis of this treatment has remained good for 3 years.

    Discussion: In order to remove the patient’s fear of dental treatment, information about the causes of the dental phobia was obtained during the medical interview. Moreover, the treatment denture and the test for chewing ability raised her motivation for dental treatment.

    Conclusion: It is important to reduce fear of dental treatment and to recognize the improvement in oral condition for patients with dental phobia.

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