There are various goals in dental treatment. The main goal in prosthetic treatment is recovery of declined oral function. Among various oral functions, masticatory function has several important objectives, such as mobilizing all senses in the oral cavity and enjoying deliciousness in addition to subdividing food. Furthermore, a decline in masticatory function causes eating habits to become unbalanced, thus having a negative effect on nutrient intake, which causes a decline in overall health. Therefore, masticatory function is an indispensable function for life.

In this article, I would like to introduce some of the knowledge about masticatory function which I has obtained so far, and to emphasize the significance of maintaining masticatory function as a gateway to general health.

Various observational studies have reported that oral health status indices, including the number of teeth and denture use and fit, are associated with dietary and nutritional status. However, despite these findings, it remains unclear whether oral function improved with prosthetic treatment contributes to improved dietary and nutritional status. Evidence has long been lacking on this topic. Recent well-designed intervention studies have reported that prosthetic treatment contemporaneous with nutrition counseling resulted in positive effects on dietary and nutritional status. In this paper, we set diet and nutrition as the clinical outcomes of prosthetic treatment, and aimed to review recent scientific evidence regarding the association between prosthetic treatment and dietary and nutritional status and the future prospects.

The importance of subjective indicators in the evaluation of medical care has received increasing attention. Typical subjective indicators include quality of life (QOL), symptoms, and satisfaction, among others. Although QOL is a widely used term, not all disciplines define and conceptualize it in the same way.

This article aims to improve the understanding of oral-related QOL and QOL assessment as clinical outcome measures. We explain the definition of oral-related QOL and the importance of QOL assessment. We describe the process of developing scales for QOL assessment, including essential points for QOL assessment. It will become increasingly necessary to conduct appropriate QOL assessments that are informed by the characteristics of QOL and to incorporate the results into various areas of practice and society.

A systematic review (SR) formulates a clinical question in a well-defined manner, identifies, selects, critically examines relevant studies, and extracts information from the included studies for qualitative and quantitative analysis. SR is significant as a basis for the practice of evidence-based medicine, clinical practice guidelines, and secondary research. This paper outlines the characteristics and essential knowledge for the SR process and paper preparation.

Systematic reviews (SRs) are broadly classified into two categories, qualitative and quantitative ones based on the process of data integration. This article focuses on the qualitative SRs. Since both SRs draw conclusions for a given clinical question at that point, the rules for collecting past empirical evidences are identical. However, qualitative SRs involve only qualitative evaluation and critical review of each primary study, without statistical integration. Then, certain conclusions are drawn based on the explicit profile of each piece of evidence. This article explains the points to consider and attentions to pay in each step of PRISMA flow diagram, when processing with qualitative SRs by indicating actual examples.

There are many times when a dentist wonders “Which material is better?”, but it is difficult to reach a conclusion from a single paper and the dentist must consider several papers. It is also difficult to answer the question “For how long is a treatment effective?”. When searching for clinical evidence, there are often no useful clinical outcomes. With those realities in mind, this paper explains reviews of basic and clinical research in materials research, and then considers the question “Can basic research (i.e. bond strength tests) predict the clinical efficacy of adhesive materials?”. In addition, the episodes and ingenuity that the author experienced when writing review papers are introduced.

In Japan, the demand for home-visit dental treatment is increasing because of a super-aging society. Since home-visit dental treatments mainly provide dental care to medically compromised older adult patients, it is necessary to understand appropriate knowledge about systemic diseases. In this paper, we will present actual cases of home-visit dental treatment to learn cerebrovascular disease, atrial fibrillation, dementia, and Parkinson’s disease. In addition, we summarized how to prepare patient referral documents which are essential for good collaboration with medical doctors, and explained the importance of conferences, and monitoring of medically compromised patients. We hope that this paper will be useful in the practice of safe and secure home-visit dental treatment.

With the development of a super-aged society, the number of people increases who need nursing care and whose oral functions have deteriorated. For these patients, it has become necessary to think of mobile dentistry not as an unavoidable necessity because of the difficulty of visiting a clinic but as a way of actively providing prosthetic care to support their lives and well-being. There are three types in the path to end-of-life care. The dental involvement differs significantly from one to the next, including a short-term focus on end-of-life care, prosthetic care and rehabilitation support, and long-term support until the decision to discontinue denture use is made, requiring appropriate judgment based on an understanding of the situation. In such cases, collaboration with visiting nurses and other professionals is essential.

Purpose: An articulator for measuring occlusal heights was developed, and the occlusal heights of hybrid composite resin crowns manufactured using CAD/CAM were compared with those of complete metal crowns fabricated using the lost-wax casting technique.

Methods: Occlusal metal crowns were fabricated using the lost-wax casting technique by three dental technicians with different years of clinical experience. Full coverage crowns (CAD/CAM crowns) made of hybrid composite resin were manufactured using milling discs and blocks of shaped material. The occlusal heights were measured with the articulator and compared among the full coverage crowns.

Results: Average occlusal height measured repeatedly using the articulator was −0.6 ± 0.7 µm, which was highly accurate. The occlusal height of the complete metal crown was −59 ± 6 µm, which was the smallest standard deviation of those fabricated by the dental technician with 20 years of experience. The occlusal height of the CAD/CAM crown from the block was 125 ± 18 µm, which was the smallest standard deviation, and it was higher than that of complete metal crowns (p < 0.05).

Conclusion: The occlusal height of CAD/CAM crowns was 154–270 µm higher on average than the complete metal crowns fabricated by the lost-wax casting technique. In addition, stable manufacturing is possible by considering the shape of materials.

Purpose: The purpose of this study was to evaluate the accuracy of intraoral scanners and compare the trueness and precision of three types of intraoral scanners with different size of scanner head based on measurements between pairs of ball abutments in vitro.

Methods: Four implants were placed on a lower jaw model. A model with a reference sphere for calibration in the lingual region was used as the reference model. After ball abutments were connected to the implants on the reference model, the three-dimensional (3D) shape of the model was measured using a 3D coordinate-measuring machine, and reference values were calculated. Subsequently, the 3D shape data (STL data) of the model was obtained using three types of intraoral scanner (CEREC Primescan [PM], CEREC Omnicam [OM], Planmeca Emerald [EM], and Planmeca Emerald with a scanner head smaller than a regular scanner head [EMS]). Using the obtained 3D shape data, the distance between pairs of the four ball abutments measured by the scanners was compared using 3D analysis software (spGauge).

Results: Larger errors were seen when scanning longer distances. The MES with a smaller scanner head had significantly larger errors with regard to both trueness and precision.

Conclusion: From an accuracy perspective, it is difficult to apply intraoral scanners to patients with a large number of missing teeth. However, these results suggest that the present method may be applicable for oral implants in patients with a few missing teeth.

Patient: A 75-year-old man complained of swelling in the maxillary gingiva and occlusal discomfort with a removable partial denture. Low occlusal vertical dimension (OVD) and irregularity of the occlusal plane were found due to severe attrition of artificial teeth and natural mandibular teeth. After modifying the occlusal plane and determining the OVD with an interim restoration, an overdenture in the maxilla and a final fixed prosthesis in the mandible were applied.

Discussion: In the present case, the overdenture made it easy to modify the OVD and occlusal plane. This rehabilitation resulted in stable occlusion, improved masticatory performance, and maintained high oral health-related quality of life.

Conclusion: The rehabilitation with an overdenture for the patient with low OVD due to attrition led to good predictability.

Patient: A 70-year-old female complained of difficulty of mastication and cosmetic disturbance due to incompatibility of dentures. She had occlusal contacts only in the anterior teeth and had lost molar occlusal support. Full-mouth rehabilitation was undertaken in this case, utilizing an implant-assisted removable partial denture in the mandible and a removable partial denture in the maxilla.

Discussion: It is presumed that the patient’s complaint was resolved by utilizing implants for free-end defects to intermediate defects, and by improving the conditions of applying and receiving pressure.

Conclusion: In the present case, an excellent result was achieved by full-mouth rehabilitation with an implant-assisted removable partial denture.

Patient: The patient, a 54-year-old woman, came to our hospital complaining of masticatory disorders due to a missing molar on the right side of the mandible. Prosthetic treatment using dental implants was performed for the missing molars, and treatment of the anterior teeth was performed to reduce the load during lateral movement for the prosthetic treatment of the molars.

Discussion: Due to the remaining teeth of the patient, among the anterior teeth, only the upper right lateral incisor was treated in the process of prosthetic treatment of the molars. The lateral incisor was restored with minimally invasive laminate veneer in order to provide appropriate anterior guidance. This decision and regular occlusal checking led to a good result.

Conclusion: In this case, prosthetic treatment using dental implants and a fail-safe lateral incisor stabilized the molar prosthetic appliance, and a good long-term outcome was obtained.

Patient: A 60-year-old woman visited our clinic complaining of masticatory and esthetic disturbance. After prior prosthetic treatment of periodontal management, a maxillary complete denture and a mandibular cone-crown-telescope denture were fabricated for the patient, who had few remaining teeth and which were affected by severe periodontal disease, and the patient was followed up for 9 years.

Discussion: Mobility of the mandibular residual teeth with poor alveolar bone was decreased and the functional stability of the dentures was improved by the effects of superior cleanability and secondary splinting of the cone-crown-telescope denture. Therefore, the masticatory and esthetic disturbance was improved with a good result.

Conclusion: A cone-crown-telescope denture for a patient with few remaining teeth affected by severe periodontal disease improved the patient’s oral health related quality of life.

Patient: The patient was a 42-year male who visited a prosthodontic clinic with the chief complaint of masticatory disorders in the left upper and lower second molars. The cause of the masticatory disorders was fractures of all ceramic crowns placed in the second molars. The final treatment was performed using porcelain fused to metal crowns.

Discussion: Fracture of porcelain is one of the major troubles among posterior crowns on which the highest occlusal force is exerted. To avoid such fractures, immediate disocclusion was the most suitable occlusion for this patient.

Conclusion: In this patient with masticatory disorders in the left upper and lower second molars, a favorable outcome was achieved by porcelain fused to metal crowns over 8 years.

Patient: A 63-year-old male visited the hospital with the complaint of chewing difficulty. Only residual tooth roots were found in his maxilla. Since the patient desired a prosthesis to improve masticatory function, an implant overdenture with four locator attachments was delivered into the maxilla and a zirconia fixed partial denture with an implant abutment was installed in the mandibula.

Discussion: In this case, the entire procedure, from most of the implant diagnosis, implantation, to the dental prosthetic laboratory procedures, was performed using digital technology. An excellent fit of the framework was obtained, which may have been the result of using CAD/CAM, which is capable of accurate milling.

Conclusion: Approximately four years have passed since the implants were placed in the patient; no abnormalities were found in both the implants and the overdentures and sufficient patient satisfaction was obtained.

Patient: The patient was a 67-year-old female. She visited the hospital complaining of the poor fit of her maxillary and mandibular dentures. The mandible had severe residual resorption and the mandibular complete denture had a poor fit. The setting position of the denture base edge, arrangement positions of artificial teeth, and morphology of the polished surface were inappropriate, and the stability during denture functioning was impaired. Hence, complete dentures were produced using piezography.

Discussion: By applying piezography to the patient, artificial teeth were arranged and a polished surface of the denture base was made. The artificial teeth arrangement and polished surface morphology were harmonized with the muscle movement around the mouth and the tongue movement, and as a result, masticatory function was recovered.

Conclusion: In this case, by applying piezography, we were able to produce complete dentures that did not impair stability during functioning.

Patient: A 45-year-old female visited our hospital complaining of difficulty in mastication and esthetic disturbance due to secondary caries and detachment of a prosthesis. After removing the maxillary prosthesis, an interim denture was fabricated. Nine remaining teeth that were difficult to preserve were extracted. An interim prosthesis using temporary implants was provided at the same time as implant placement. Bilateral maxillary central incisors were preserved by applying the root submergence technique. After confirming that there were no problems with oral function and esthetics with the interim prosthesis, the final prosthesis was fabricated.

Discussion: Preserving bilateral maxillary central incisors resulted in less alveolar bone resorption, and the alveolar ridge in the pontic remains with a good outcome.

Conclusion: Appropriate use of the interim prosthesis with temporary implants has contributed to the improvement of the patient’s QOL by ensuring oral function and esthetics and transitioning to the final prosthesis.

Patient: The patient was a 48-year-old male who presented to our clinic with the chief complaint of missing anterior teeth. Suspecting sleep apnea syndrome, he had consulted an internist, who diagnosed him with obstructive sleep apnea syndrome. After placing a mandibular advancement splint, he underwent oral myofunctional therapy.

Discussion: An oral appliance in the anterior mandibular position is effective in patients with obstructive sleep apnea. However, in this patient, an oral appliance in the 50–75% anterior mandibular position did not improve airway volume. Therefore, oral myofunctional therapy was performed to expand the airway.

Conclusion: This was a case of obstructive sleep apnea in which airway morphology did not improve with the use of a mandibular advancement splint. It was important to combine oral myofunctional therapy with patient education.

Patient: A 21-year-old female patient presented with esthetic dissatisfaction due to discoloration of a maxillary lateral incisor. As the maxillary right lateral incisor exhibited internal root resorption, it was decided to extract the tooth. The patient opted for fabrication of a resin-bonded prosthesis (RBP) using zirconia ceramics.

Discussion: The use of zirconia ceramics with high flexural strength as a framework material for the RBP and the strong bond between abutment teeth and retainer using a resin luting agent achieved satisfactory functional and esthetic results.

Conclusion: Zirconia ceramics are recommended as the framework material for RBP. Zirconia RBP is a less invasive prosthetic treatment, and this case exhibited a satisfactory long-term clinical outcome.

Patient: The patient was a 39-year-old woman who visited the hospital complaining of difficulty in mastication with a complete denture. A new denture was manufactured by piezography to restore functionality. Piezography achieved a form that was in harmony with the movement of the living body and the lingualized occlusion reduced the lateral force of the denture during functioning and secured the tongue space. Therefore, the denture was maintained and stabilized, and masticatory function was restored.

Discussion: Piezography is a useful technique for obtaining denture stability in cases with high ridge resorption. In addition, food crushing ability was improved by adding lingualized occlusion.

Conclusion: A complete denture that matched the movement of the living body was attached to the young patient, and masticatory function and QOL were improved.