When tooth loss occurs later in life, ageing and multimorbidity impact dental treatment decisions. There is sufficient evidence to state that the mandibular implant overdenture is a well-established treatment modality, certainly in non-dependent edentulous individuals, but little is known on the very old and geriatric edentulous patients. They often present unfavourable anatomical conditions, xerostomia and a lack muscle control. Although the benefits of dental implants are well documented, elderly adults are often reluctant to agree to an implant insertion, even if cost is removed as limiting factor. The main reasons for implant refusal are the fear of surgery and pain. The present paper describes the use of minimal-invasive and simple treatment concepts for elderly, edentulous patients. It further highlights possible complications, which may arise with the onset of dependency and/or frailty and advises further simplification of the implant-restorations when needed. Recall and maintenance in this group of patients is crucial to assure the patients’ benefit from the intervention until late in life.

In regard to a critical discussion on the topic of “keratinized gingiva surrounding the implant” and its relation to the “perio-implant prosthesis”; cautious treatment of intervention based on scientific evidence is thought to be important in the former, while careful prosthetic design is paramount in the latter. In the “Scandinavian Approach”, “necessity” is the basis of the intervention principle; however in the “American Approach”, the subjective decisions of the practicing clinician seem to play a larger role on the extent to which treatment is conducted. The difference between the two approaches is the criteria for clinical intervention which can be categorized in terms of what should be done, what can be done, what does not have to be done, and what should not be done.

In this article, the theme of fixed prosthodontic treatment of patients with periodontitis is discussed by categorizing treatment approaches into the Scandinavian approach and the US approach, which were described in the last issue by Drs. Hideaki Hirooka and Tokuo Matsui, respectively. The Scandinavian approach is based on the concept that the clinician should never do more than what is absolutely necessary, but should always be prepared to do what the situation demands, whereas the US approach aims at clinical outcomes using periodontal/regenerative surgeries to adjust the alveolar bone level and to obtain a shallow gingival sulcus and attached gingiva. These approaches have conceptual similarities, although their treatment approach is completely different. I hope that this discussion will provide an opportunity for readers to further consider the role of the prosthodontic specialist in the treatment of periodontal disease.

Material selection in dental CAD/CAM system is indispensable for utilization of digital dentistry in crown bridge. However, in a dental CAD/CAM system, a very wide variety of systems are employed by a combination of materials and processing methods, and these systems tend to diversify year after year and, the number of usable materials increases. Therefore, it is necessary to grasp the basic knowledge of each method and material based on the latest information for material selection. In this review, materials used in dental CAD/CAM systems are roughly classified into three types, a ceramic type material, a metal type material, and a resin type material, and their characteristics are described in order to assist optimal material selection. Furthermore, a ceramic type material is divided into two types, glass ceramics and zirconia. Especially, dental zirconia increases to 10 kinds and quickly expands to Japanese dental restoration. CoCr alloy is most frequently used as a metal type material for dental CAD/CAM system. Because this alloy can be formed by not only maschining but also SLM and a machining/sintering system. A resin type material is divided into eight types, acrylic resin, polyamide resin, polyacetal resin, glass fiber reinforced resin, composite resin, wax, polyurethane, and super engineering plastic, namely PEEK and PEKK. Especially, composite resin, so-called hybrid resin, is rapidly applied due to the health insurance approval.

Implant treatment benefits from digital technology throughout its processes from treatment planning to surgery and even prosthetic treatment. Besides implant planning and simulation based on CT and STL data, the CAD/CAM system in guided surgery and superstructure fabrication has been increasingly employed. However, completely accurate placement cannot be achieved even with the guided surgery. In addition, no criterion has been set for selecting patients and materials for the CAD/CAM prosthesis. The present article summarizes the digital workflow on implant treatment, describing the usefulness of and problems with the guided surgery and CAD/CAM implant superstructure.

Stem cell research in the field of dentistry has been widely conducted as regenerative research, targeting bones, periodontal tissues, and teeth. In the field of prosthodontics, stem cell research has recently helped achieve the establishment of disease models and drug discovery research. Regarding regenerative medicine, the use of stem cells is thought to be a major key factor for achieving reliable regenerative medicine. The tooth developmental process goes through an induction phase between the epithelial and mesenchymal stages regulated by complex signaling molecules. Therefore, the mimicking process will be affected by the type of stem cell selected. In the present report, we will introduce the different types of stem cells that can be applied to regenerative dentistry.

Patient: The patient was a 69-year-old male with decreased occlusal vertical dimension and masticatory disturbance associated with teeth loss and attrition. Using an analysis of free-way space, cephalometric analysis and diagnostic wax-up as references, the occlusal vertical dimension was increased by means of interim restorations and transitional dental prostheses. Periodontal treatment or root canal treatment was performed at this stage. After the occlusion was stabilized, the interim restorations were replaced with definitive dental prostheses.

Discussion: After a suitable mandibular position for functional mandibular movements was investigated by using interim restorations and transitional dental prostheses, definitive dental prostheses were delivered, resulting in a favorable prognosis.

Conclusion: A suitable mandibular position for increasing the occlusal vertical dimension should be established by performing reversible treatment.

Patient: The patient was a 64-year-old man who complained of pain and esthetic disturbance with removable dentures. His only remaining tooth was the right mandibular first premolar. Pain in the underlying mucosa of the denture and esthetic disturbance were diagnosed due to his big mandibular torus, thinning of the mandibular mucosa, and malposition of artificial teeth. Six implant bodies were placed in the maxilla and mandible, respectively. Then, provisional restorations whose good shape, functionality, aesthetics and hygiene were confirmed by digital scanning were used to fabricate the final full zirconia restorations. The patient was satisfied with the function and esthetics even three years after treatment.

Discussion: Accurate digital reproduction of the shape of the provisional restorations to the final restorations contributed to the patient’s satisfaction.

Conclusion: Bone-anchored implant restorations for edentulous jaws were found to be effective in this patient with mandibular torus.

Patient: A 44-year-old female presented with trismus due to anterior disc displacement without reduction two months before the first visit. Narrowed left condyle, premature contact at the occlusal facet of the protrusion in the left molars and clenching were observed. Occlusal reconstruction with a dental implant and fixed partial prosthesis was performed after disc rehabilitation and disappearance of temporomandibular symptoms by manipulative reduction and occlusal appliance therapy.

Discussion: Early initiation of treatment after disc displacement and establishment of substantial occlusion with a fixed prosthesis are likely to be effective for rehabilitation of anterior disc displacement without reduction and stabilization of the temporomandibular joint.

Conclusion: Early rehabilitation of anterior disc displacement without reduction and occlusal reconstruction resulted in a good outcome in this patient with anterior disc displacement without reduction.

Patient: A 42-year-old female diagnosed with recurrent left maxillary mucoepidermoid carcinoma underwent partial resection of the hard and soft palates. Matsuura’s classification of maxillary deficiency was H3S1D2T0. The patient developed dysarthria after surgery due to palatal defects. An immediate prosthesis was placed during the healing period. A final maxillar prosthesis was fabricated using the flange technique while paying special attention to the form of the lateral and posterior border of the prosthesis.

Discussion: In this case the clarity of the patient’s utterances was significantly improved by the final prosthesis. A good outcome was achieved by making the form of the border and flange of the prosthesis during the fabrication process.

Conclusion: The form of the flange and the position of the posterior border which overlies the remaining soft palate are important for improving both dysarthria and dysphasia in patients with defective palates after surgery.

Patient: A 56-year-old female visited our clinic with a chief complaint of esthetic problems and masticatory disturbance caused by displacement of the maxillary central incisor. She was not using a distal extension removable partial denture in the left side of the mandible. Orthodontic extrusion was performed before extracting the maxillary central incisor in the periodontal initial treatment. Dental implants were used to counter the loss of occlusal support and as an anterior guide.

Discussion: The orthodontic extrusion before extraction was effective for leveling the alveolar bone in this case. Occlusal balance and high satisfaction of the patient were achieved over ten years by the implant-supported prosthesis.

Conclusion: The masticatory dysfunction caused by the loss of occlusal support was resolved with good results after treatment using dental implants.

Patient: The patient, a 75-year-old male, complained of masticatory dysfunction caused by pain and repeated fracture of dentures. The diagnosis was a decrease of occlusal vertical dimension caused by the attrition of teeth and left-side deviation of the mandibular position. To improve the decrease of occlusal vertical dimension and the mandibular deviation, treatment dentures were applied. After rehabilitation for approximately 3 months and stabilization of the mandibular position, the final prostheses were fabricated. With periodic maintenance, a good prognosis was obtained.

Discussion: Rehabilitation with treatment dentures and stabilization of the mandibular position led to exact reconstruction of the intercuspal position in the final prosthesis.

Conclusion: For this case with infraocclusion caused by the attrition of teeth and deviation of the mandibular position, a good prognosis was obtained by using treatment dentures.

Patient: The patient, a healthy 22-year-old female, had 9 congenital missing teeth in the upper and lower jaws. After orthodontic treatment, the patient visited our department to restore esthetic and functional disorders of all edentulous spaces. An implant-supported fixed prosthesis for the edentulous spaces of the maxillary and mandibular premolars and a fixed partial denture for the mandibular incisal edentulous region were applied.

Discussion: As a result of connective tissue grafting and ridge shaping to fit ovate pontics in the lower anterior edentulous region, long-term esthetic and functional stability was obtained even without implants.

Conclusion: It has been three and a half years since the treatment was finished and the patient has not experienced any complications. This case indicates the importance of continuous maintenance for acquiring a good long-term prognosis.