The removable partial denture is a prosthesis that is used to a partially edentulous region. Among the basic concepts, “Protect residual oral tissue” is the most prioritized item. The first of the principles of denture design is the “minimization of denture mobility” which aims at reducing the displacement of the denture during its function to reduce the overloading of the abutment teeth. For the control of denture mobility, a strong retention is never necessary. Only by increasing the mechanical retentive force represented by the undercut retention, the over loading is imposed on the abutment tooth. It is possible to produce a sufficiently stable denture with minimum retention by regulating the slight movement direction in the function mainly on the action of support and bracing.

A removable partial denture with implant support (IRPD) is clinically available for maintaining occlusion and obtaining denture stability. Symmetrical placement of a few implants will not only improve the supporting position and area in the dental arch, masticatory function, and comfort but also prevent ridge resorption and contribute to long-term success. Particularly, IRPD would be best prosthetic rehabilitation method for Eichner C1 cases without an occlusal vertical stop, because it is very difficult to perfectly prevent the rotational change of dentures using conventional RPDs.

In this article, the term “IRPD” is proposed as a general term for a removable partial denture with implant support. Examples of success and failure in IRPD cases are shown, and types and indications of IRPD are discussed. The outline of effective techniques, implant positions, and designs of IRPD are explained. A typical long-term observation of an IRPD case is also described.

There are some treatment options available for people with partially edentulous arch; conventional removable partial dentures, implant-supported fixed prostheses, shortened dental arch, and implant-assisted removable dentures (IARPDs). IARPDs, the strategic addition of implants beneath the denture base, may be a more appropriate option in certain circumstances, although the reliability of combining natural teeth and dental implants in one removable prosthesis is controversial. Various factors can affect treatment planning, such as aesthetic or functional demands, treatment costs, oral hygiene, extent of ridge resorption, condition of remaining teeth, interocclusal space, and general medical condition. In general, IARPDs can demonstrate great advantages over conventional removable partial dentures in the denture stability, comfort due to simplified shape of denture base, and aesthetics related to metal clasps. Additionally, IARPDs can be more favorable than implant-supported fixed prostheses in regard to the minimally invasive surgical procedure, reducing economic cost, aesthetic restoration of facial collapse, and ease of maintenance. However, there is no standardized protocol of IARPD treatment so far because of the lack of clinical evidence. The purpose of this article is to organize current clinical information of IARPD treatment in a logical manner, as it relates to clinical features, literature-based consideration, and clinical tips with the view to a better prognosis and a greater patient satisfaction.

The application of conventional partial denture (CRPD) is considered to be limited. Hence, the possibility of implant assisted removable partial denture (IARPD) has been recently studied. In this paper, we focused on the following two points: 1) Variations other than fixed implant prosthesis for mandibular unilateral free-end defect; The results of practice-based research by patient reported outcomes on CRPD, non-metal clasp denture and non-intervention (SDA) were presented, and clinical cases of IARPD were shown. 2) For bilateral multiple free-end defect beyond SDA, CRPD is often difficult, and clinical cases and scientific evidence of IARPD used as a solution in such cases were shown.

Hospitalized older patients undergoing convalescent rehabilitation tend to experience deterioration of oral health. Moreover, many of them suffer from malnutrition and sarcopenia. Impaired orel health, malnutrition and sarcopenia are all negatively related to rehabilitation- and health-related outcomes. Therefore, it is necessary to promote oral management by dental professionals, and proactive nutritional support, exercise, etc. by multi-professionals while performing clinical practice and risk management of comorbid diseases for such patients.

The oral function including the number of teeth remained is largely involved with dietary intake. It has been reported that a person tends to avoid chewy food such as vegetables but prefer food full of starches along with their teeth loss. To keep proper nutrient intake for the older people, it is necessary to administer nutrition based on the state of the oral function and dentures of each person, which highly requires cooperation between dentistry and dietetics. Recently, intervention studies have also been conducted combining nutrition guidance and improvement in the oral function or dental prosthesis.

There, the cooperation between dentistry and dietetics suggests the possibility of a synergy effect on health maintenance and healthy life expectancy extension for the elderly generation, which cannot be obtained if separately provided.

In the future, support for “maintain eating” will be required more, and cooperation between dentistry and dietetics will be indispensable.

In recent years, sarcopenia prevention and flail prevention are regarded as important. As a way to achieve healthy longevity, dental care that incorporates a nutritional perspective is necessary. On the other hand, dentistry has not incorporated the viewpoint of masticatory disorders due to motor disorders in the diagnosis of masticatory disorders. Aging and diseases that develop with aging cause sarcopenia throughout the body and disturbance of the motor control system, affecting the masticatory function. Whether or not motor disorders are involved in the cause of masticatory disorders can be evaluated by tongue pressure or diadochokinesis. If motor disorders are involved, an approach to motor disorders is essential. At that time, the necessary outcome is nutrition, and the intervention content is nutrition guidance in addition to functional training.

Purpose: In the 2016 dental fee revision, prosthetic crown shade selection tests, denture chewing function tests, and tongue pressure tests became covered by national health insurance. The purpose of this study was to clarify the implementation status of these tests in the clinical setting and to study the extent of their implementation compared with the estimates given in the Health Technology Assessment Proposal at the time of their introduction.

Method: The number of implementations of these tests in medical practice (subtypes) was investigated in the Ministry of Health, Labour, and Welfare’s Social Medical Practices Survey conducted in 2016, 2017, and 2018. The proportion of prosthetic crown shade selection tests performed during cementation of metal crowns with resin-facing and hard resin jacket crowns, the proportion of denture chewing function tests performed during insertion of removable partial dentures (multi edentulous) and complete dentures, and the proportion of tongue pressure tests performed during insertion of palatal augmentation prostheses for the purpose of improving contact function were compared. A comparative study of these tests against the estimates in the Health Technology Assessment Proposal was performed.

Results: The crown prosthetic shade selection test was performed in approximately 5% of applicable cases, which was approximately 7% of the estimated number. Almost no denture chewing function tests were performed in 2016, and their number increased slightly to 0.2% in 2017 and to 0.4% in 2018. Beginning in 2016, multiple calculations of tongue pressure tests were performed in necessary cases. The proportion of tests was 12%–13% of the estimated number. From 2018, their applicability expanded, and there was a large increase in implementation.

Discussion and conclusions: The actual numbers of all the tests were far below those estimated in the Health Technology Assessment Proposal. This finding suggests that with respect to new medical technology proposals, in addition to monitoring the change over time, it is necessary to pay attention to the implementation estimates in the future.

Patient: A 5-year-old edentulous male patient was brought to our hospital with the chief complaint of pronunciation and chewing difficulties with his mandibular complete dentures. The intraoral view suggested that the patient had severe alveolar ridge absorption and two implant abutments. We attempted to fabricate a two-implant supported overdenture by applying piezography to improve the symptoms.

Discussion: In providing mandibular complete dentures for this patient with severe ridge resorption, a new approach of using piezography with functional dentures was successful in positioning the artificial teeth in consideration of the perioral muscles and tongue movement, and designing a morphologically appropriate polished surface. Accordingly, the patient’s masticatory function improved.

Conclusion: To obtain a favorable outcome in this patient with severe alveolar ridge resorption, the use of piezography with new functional dentures was successful, and it increased patient satisfaction.

Outline of the case: A 67-year-old male patient presented with masticatory dysfunction caused by malocclusion of removable dentures. Since the loss of occlusal support had induced a decreased vertical dimension and there was an occlusal plane discrepancy, occlusal reconstruction was performed with treatment dentures, and then the final dentures were made.

Discussion: Masticatory dysfunction was correlated with the loss of molar occlusion in this case, so the restoration of occlusal support and occlusal reconstruction were attempted by treatment dentures. Then we made the final dentures based on the treatment dentures. They were designed to make the support as rigid as possible and to avoid overloading of the remaining teeth. As a result, no tooth loss was observed after delivery of the final dentures. The chewing score and patient’s satisfaction were also improved.

Conclusion: Improvement of masticatory function was achieved by the final dentures after occlusal reconstruction with treatment dentures.

Patient: A 68-year-old male presented with the chief complaint of difficulty in chewing due to maladaptation of removable partial dentures. All occlusal supports except the canine contact on both sides had been lost, and disturbance of the occlusal plane was observed. After correction of the occlusal plane and canine guidance without changing the vertical dimension of occlusion, maxillary and mandibular removable partial dentures were fabricated.

Discussion: Correction of the occlusal plane and anterior guidance by utilizing the canines on both sides as an index of the mandibular position contributed to stabilization of the intercuspal position and recovery of chewing function.

Conclusion: The provision of appropriate canine guidance and occlusal reconstruction using removable partial dentures were effective for this case of prospective occlusal collapse with four remaining canines in good condition.

Patient: The patient was a 70-year-old female who complained of aesthetic and functional problems with her dentures in which her palatal torus caused ill-fitting and mandibular ridge resorption resulted in functional instability. A roofless metal plate denture for the maxilla and a cone crown telescopic denture for the mandible were fabricated and combined with magnetic attachments.

Discussion: With the final prostheses masticatory function was greatly improved due to the support and retentive effects of the magnetic attachments and the effects of strong support, bracing and retention by the cone crown telescopic abutments.

Conclusion: By using a dental prosthesis with magnetic attachments and cone crown telescopes, we improved chewing and aesthetic disorders and gained good results for this patient with high aesthetic demands.

Patient: The patient was a 47-year-old man who complained of mastication disorder due to the loss of many teeth. Immediately after extraction of the maxillary remaining teeth, a complete denture was inserted. The maxillary denture was duplicated, and it was used as a diagnostic/surgical stent. Implants were inserted into the maxilla and a provisional fixed prosthesis with immediate loading was placed. The final implant fixed prosthesis was placed seven months after the provisional placement.

Discussion: This type of stent enables the implant to be placed as precisely as planned, and allows the placement location to be modified slightly if necessary during surgery and the occlusal relationship obtained by the complete denture to be transferred to that by the final implant prosthesis, reducing the risk of troubles in the treatment process.

Conclusion: The use of a stent copied from the complete denture contributed to good placement of the implant, good occlusal transfer, and good performance of the fabricated implant prosthesis.

Patient: A 63-year-old woman presented to the dental clinic with the chief complaint of esthetic problems due to the conspicuous appearance of the denture clasp and masticatory disability due to accidental tongue biting. A maxillary complete denture and a mandibular partial denture fabricated with extracoronal attachments were delivered to the patient.

Discussion: Among the various approaches of prosthetic treatment for the edentulous mandibular molar region, the extracoronal attachments that were specifically designed to address the patient’s chief complaint of compromised esthetics were successfully fabricated and delivered to the patient.

Conclusion: The use of extracoronal attachments for the remaining anterior teeth ensured esthetic restoration of the edentulous areas and improvement in the denture with added stability, resulting in favorable postoperative outcomes and patient satisfaction.

Patient: A 60-year-old woman visited our clinic with the chief complaint of masticatory disturbance due to mobility of a maxillary left fixed partial denture and distal extension missing molars in the right mandible. Decreased occlusal vertical dimension and irregular occlusal plane were found. Occlusal reconstruction using an implant-supported prosthesis was performed to correct these issues.

Discussion: Although eight years have passed since the final prosthetic procedure, it is suggested that the full-mouth prosthetic procedure allowed stable occlusion and that continuous maintenance allowed the residual teeth and implant-supported region to stabilize over time.

Conclusion: In the present case, occlusal reconstruction with bite-raising through an implant-supported prosthesis in the edentulous region and crown restoration of the residual teeth improved masticatory and cosmetic disturbances.

Patient: A 64-year-old man complained of masticatory disturbance (Eichner B4) resulting from loss of retention of a mandibular removable partial denture (RPD). A broken clasp of the old denture, worn artificial teeth, extruded teeth as well as low occlusal vertical dimension were found. At first, treatment dentures were used to improve the occlusal position. After a reassessment, the improved occlusal position was transferred into the final dentures.

Discussion: In this case with multiple missing teeth and loss of occlusal support, accurately setting the occlusal position for the final dentures resulted in stable occlusion and good prognosis. Treatment dentures explored morphologically and functionally allowable occlusion position.

Conclusion: The use of treatment dentures effectively improved the jaw relationship in this RPD case with non-occlusal vertical support.

Patient: A 38-year-old man presented with the chief complaint of poor appearance. He was diagnosed with extensive type severe aggressive periodontitis, cuspal interference, and esthetic disturbance with malformation of anterior teeth and a spaced arch. After removing ill-fitting restorations, temporary crowns were set. Regenerative periodontal therapy was performed followed by periodontal initial treatment and endodontic therapy. By partial orthodontic treatment and provisional restorations, the occlusal plane and the occlusal scheme were modified and final prostheses were set. The post-treatment course was uneventful.

Discussion: Motivation of the patient, as well as periodontal treatment and good distribution of functional force, were essential for a good prognosis.

Conclusion: In patients with poor self-image due to esthetic disturbance, occlusal interference and periodontal disease, periodontal treatment followed by orthodontic and prosthodontic treatment is important for a prolonged good prognosis.

Purpose: The patient was a 69-year-old female with the chief complaint of masticatory disorders in the right molar region. The abutment teeth of her fixed prosthesis in the upper left molar region needed to be extracted. Attrition of the occlusal surface of the dental prosthesis indicated that the patient had bruxism. Since the occlusal supporting area on both sides was almost completely missing, the edentulous sites were reconstructed with implant-supported fixed prostheses.

Discussion: Implant-supported prostheses for bruxism patients need to be monitored carefully, especially the occlusal relationship which may cause excess loading on the implants.

Conclusion: Implant-supported fixed prostheses were effective for this patient whose occlusal supporting area on both sides was almost completely missing. In this case, wearing an occlusal splint at night and regularly scheduled check-ups resulted in the preservation of masticatory function and occlusal support without any complications up to 4 years 6 months so far.