Purpose: The aim of this review article was to present the current concept of “bone quality” which was stated to be important parameters for bone diagnosis other than BMD by the National Institute of Health (NIH), based on collagen fibers, biological apatite, and bone cells.

Results: The term “bone quality” has been considered to be synonymous with bone mineral density (BMD) based on radiographic and sensible evaluations in prosthetic dentistry. However, the concept of bone quality, which is comprised from bone architecture, bone turnover, bone mineralization, and micro-damage accumulation, was proposed by the NIH in 2000. The current concept of bone quality is completely independent of BMD. Moreover, our investigations have shown that collagen fibers, biological apatite (BAp), and bone cells such play important roles in regulating the current concept of bone quality in bone around hip and dental implants.

Conclusions: The current concept of bone quality plays crucial roles in understanding bone mechanical functions. Collagen fibers, BAp and bone cells are the main factors affecting bone quality under loaded conditions. Our findings strongly suggest that understanding and accepting the current concept of bone quality is required in prosthetic dentistry.

Maxillomandibular registration plays an important role for the success of complete denture treatment. The methodology to determine horizontal mandibular position has a lack of objective indicators, leading the difficulty in maxillomandibular registration. Gothic arch tracing (GoA), a device to diagnose mandibular movements, has been used as one of methods to determine horizontal mandibular position for a long time. Occasions to use GoA, however, seem to be decreasing in recent years. Furthermore, GoA is not described in the recent textbooks of the United States, which shows reduced opportunities for the education about GoA. The topics of this manuscript are as below; 1) the usefulness and significance of GoA, 2) the problem and notice of GoA, 3) how to determine the goal of maxillomandibular registration. In addition, we would like to describe the necessity of GoA in the complete denture treatment.

Since the DICOM (Digital Imaging and COmmunication in Medicine) data of CT (Computed Tomography) is digital data, the implant treatment is highly compatible with digital dentistry and digital technology has been introduced from a relatively early stage. In addition to simulation software, guide surgery and safe surgery using a navigation system, the superstructure of the implant using CAD/CAM has also become widespread today.

Diffusion of optical impressions extends the digital workflow not only to laboratory but also to clinical procedures, and in some systems, from the optical impression to the construction of the superstructure of the implant are systematically developed, and the full digital workflow It can be said that top-down treatment by approach has come close to completion.

On the other hand, it is also true that digital workflows related to optical impressions are less flexible than conventional workflows, and there are some restrictions, such as highest level of accuracy obtained by conventional workflows is not guaranteed. In this article, we will present changes and utilization of optical impression in implant treatment and discuss future development with focus on technical limitations currently faced.

Erythematous candidiasis (EC) is an atrophic variant of oral candidiasis, which results in oral pain and burning, and dysgeusia. The course of the disease is often chronic and recurrent. Thus, an early diagnosis and appropriate treatment are necessary. The species most frequently implicated in EC is Candida albicans; however, other species have been encountered. The diagnosis of EC in clinical practice is established with an exfoliative cytological examination. Hyposalivation is the most important predisposing etiological factor for EC. Since chronic EC does not resolve spontaneously, antifungal therapy and the management of dry mouth is required for its resolution. Gargling with a mouth rinse, and the application of a saliva substitute, artificial saliva and moisturizing gel can prevent an increase in the degree of Candida colonization, moisten the oral mucosa, and strengthen the anatomical barrier, and is considered to be an appropriate measure for the treatment of EC in patients with dry mouth. In cases of EC in which denture use is an etiological factor, the disinfection of dentures is essential. A topical application of an antifungal agent to the dentures has been shown to be effective in some cases.

Denture plaque has been recognized as microbial biofilm on denture, and has been reported to be a causative factor of oral candidiasis like denture induced stomatitis, angular cheilitis, and oral thrush. In addition, denture becomes a plaque harbor, to cause respiratory and/or gastrointestinal infections. Hence appropriate denture plaque control is essential to health for the elderly.

In this review, we describe what is denture plaque, and then the feature of the commercially available denture cleansers.

Denture relines using resilient silicone or resilient acrylic material had been implemented in the daily practice for decades. However, this remedy had been controversial and ridiculed among the prosthodontists as “one of the escapes from standard treatment.” However, the rise of global elderly populations resulted in the advent of a super-aging society in several regions; the treatment has been accepted as one of the alternatives treatment for those with limited access or limited time for care. Under such circumstances, Public insurance in Japan has covered the remedy since April 2016; limited to indirect reline for a mandibular denture. In this report will summarize clinical evidence of resilient relined denture on clinical subjective and objective outcomes, both with silicone and acrylic materials. Also, the material characteristics, the clinical techniques are described. The adverse effect of the material is the deterioration: losing elasticity of acrylic, and silicone peeling from denture base. Many clinical has impressions that the status and timing of deterioration differ from patient to patient. Thus, once the patient factors affecting the deterioration of the material are clarified, it will be implemented to make a prior judgment of application to the patient and to predict the deterioration timing. A a proper examination to support the clinical decision as to whether flexible reline denture is adaptable will also be a future issue to be clarified.

In the case of applying a lining with a soft relining material to the removable denture, the silicone-based soft relining materials, which have a property of relatively good long-term stability, is often used. Notes and tips on the lining using silicone-based soft relining materials are introduced in this report. In addition, the methods of adjustment of dentures after lining with soft relining materials are explained. The home care methods of dentures with a soft relining material is different from dentures with conventional hard denture base materials. The effects of the mechanical cleaning by a denture brush and the chemical cleaning by a denture cleansing agent on the surface morphology of soft relining materials are also explained.

The number of elderly individuals is rapidly increasing in Japan, which has come to be known as a super aging society, while the percentage of edentulous patients is also high. Furthermore, patients with severe alveolar resorption, and/or a thin and non-resilient residual mucous membrane are on the rise. Soft denture liners that have a cushioning effect towards masticatory force are generally efficient for intractable cases. Several studies concerning the clinical efficiency of soft-lined dentures have been reported and application of a soft denture liner for reline recently became covered by the national insurance system in Japan as part of a medical fee revision in 2016. Types, material characteristics, and functional efficacy of soft denture liners, as well as methods of reline using soft denture liners are described in this paper.

Patient: The patient was a 60-year-old woman on her first visit to our clinic. The chief complaint was masticatory difficulty caused by looseness of the upper right premolars (tooth numbers 24, 25). Advanced periodontitis with pathological migration of the teeth and disruption of the occlusal plane was also observed. After periodontal treatment, full-mouth reconstruction using a prosthetic procedure was performed in order to restore normal occlusion.

Discussion: We believe that it is possible to attain satisfactory attachment by temporarily securing mobile teeth using a provisional restoration at the time of periodontal therapy, and then fixing them permanently, with the aim of stabilizing occlusion through prosthetic rehabilitation after regeneration therapy.

Conclusion: When performing prosthetic rehabilitation on loose teeth caused by advanced periodontitis, regenerative periodontal therapy to regain lost periodontal tissue and actively improve the general oral environment is a desirable treatment that can be used to achieve better masticatory function.

Patient: The patient was a 71-year-old male with the chief complaint of masticatory disturbance due to hemi-mandibulectomy. Surgical resection due to mandibular deviation to the affected side had been performed, causing degradation of stability and masticatory function of the initial mandibular prosthesis.

Discussion: In this case, a new mandibular prosthesis was fabricated and the positions of artificial teeth were arranged to improve masticatory function, and a palatal ramp was used in consideration of setting the occlusion support area, thus contributing to successful objective evaluation of treatment effects.

Conclusion: After insertion of a new mandibular prosthesis and dentures for the maxilla with palatal ramp, satisfactory stability and improvement of the masticatory function were obtained with minimal adjustment.

Patient: A 72-year-old man presented with the chief complaint of masticatory dysfunction due to missing teeth and maladaptation of dentures. Combined periodontal treatment was conducted, and maxillary overdenture and mandibular cross-arch fixed prosthetics were placed for multiple missing teeth and reduced periodontal support.

Discussion: Occlusal improvement using treatment dentures and provisional restorations and appropriate periodontal therapy produced favorable results. The maxillary overdenture and mandibular cross-arch bridge with distal cantilever were used for the final restoration. The prognosis was good due to adequate periodontal therapy and prosthetic treatment.

Conclusion: The prognosis was good due to adequate periodontal therapy and prosthetic treatment for this patient who had multiple missing teeth and reduced periodontal support with advanced periodontal disease.

Patient: The patient was a 61-year-old female with the chief complaint of maxillary anterior teeth mobility and concern over losing them. After extraction of the maxillary central incisors, an immediate denture was delivered to the patient. After periodontal treatment including surgical procedures, we started to make a maxillary removable partial denture.

Discussion: The cast reinforcement embedded in the denture base and the artificial teeth made the partial denture rigid. As a result, denture fracture was prevented, and because of periodical periodontal maintenance, no maxillary anterior teeth were lost.

Conclusion: A good prognosis was obtained with a maxillary removable partial denture with reinforcement for a patient with missing maxillary anterior teeth.

Patient: The patient was a 64-year-old female with the chief complaint of poor esthetics of 4321|123. Esthetic dissatisfaction and masticatory disturbance were caused by the tipping of facing porcelain of 321|123 fused to metal splinted crowns installed about 25 years ago and by the tilting of 4| to the buccal direction. To resolve the patient’s chief complaint, a fixed prosthesis and dental implant were conducted.

Discussion: At first, oral hygiene condition was not good but has been improving by repeated scaling and oral hygiene instructions. Thus far, the use of a night guard for bruxism has prevented tipping of the facing porcelain and root fractures.

Conclusion: A case with esthetic dissatisfaction and masticatory disturbance treated by a fixed prosthesis and dental implant is reported. Key words:

Patient: The patient was a 78-year-old female with the complaint of dysmasesis, secondary to loss of the maxillary anterior crown and removal of implants in the mandibular left molars. Owing to the severity of the residual ridge resorption of the mandibular left molars, poor occlusal support, and the patient’s desire to avoid extensive surgery, a metal base denture was worn in the mandible and an overdenture in the maxilla.

Discussion: Wear of the overdenture in the maxilla and the mandibular framework denture designed for a partially edentulous arch suppressed overloading of the maxillary anterior teeth. The improved mandibular stability of this denture gave the patient a more favorable prognosis.

Conclusion: The use of a removable partial denture in the case of severe mandibular ridge resorption and poor occlusal support can yield good therapeutic results.

Patient: A 51-year-old female complaining of masticatory disturbance visited our department. Her unstable occlusion had gradually presented due to extraction of her lower left first molar one month before visiting us. Deformation of her left condyle and a lack of convergence in her terminal points of tapping movements were observed by X-ray and mandibular movement findings. From these findings, she was diagnosed with masticatory disturbance due to osteoarthritis. From the results of mandibular movement analysis, a posterior movement of over 1 mm in her left condyle during the lateral excursion was revealed. Therefore, a functional bite impression (FBI) technique was applied to fabricate a prosthesis that harmonized with her mandibular movements.

Discussion: Through the FBI technique, her occlusal stability was obtained, and was successfully maintained during follow-up for over 8 years.

Conclusion: In this patient with unstable occlusion, a favorable outcome was achieved by the FBI technique.

Patient: A 60-year-old female suffered from looseness and pain in her teeth and complained of denture instability. After examination, she was diagnosed as severe chronic periodontitis with occlusal trauma and masticatory disturbance caused by the loss of posterior occlusal support and anterior guidance. Periodontal treatment was provided, and anterior guidance was reconstructed using a provisional restoration.

Discussion: To reconstruct the anterior guidance in the present patient, the final restoration was precisely produced using a semi-adjustable articulator and a custom incisal guide table.

Conclusions: The establishment of anterior guidance is important for acquiring a good long-term treatment prognosis. The application of a provisional restoration considering an appropriate anterior guidance and transferring this information to the final restoration using a custom incisal guide table is a useful approach.