“Low nutrition” is a problem for the elderly in terms of preventing frailty. The causes of mastication disorders can be divided into two categories: organic disorders and motor dysfunction. The former is caused by loss of teeth and other organs of mastication, for which restoration of the occlusion through prosthetic treatment such as dentures is a necessary method to improve function. The latter is due to a decline in motor function caused by a disturbance in the motor control system and muscle weakness in the oral cavity, which is caused by physiological aging and cerebrovascular disease. Dentistry has followed the “disease model” to prevent and treat dental caries and periodontal diseases, as well as prosthetic treatment, with the aim of improving masticatory disorders. However, in the “life model”, interventions such as dietary guidance and motor training are necessary to prevent sarcopenia caused by under-nutrition and functional decline due to ageing against a background of chewing disorders. We believe that dental practitioners must understand the causes of the decline in masticatory function in the elderly and the relationship between the nutritional status of the elderly and practice dental care with nutritional outcomes based on a life model.

The development of the Bonwill articulator to the Walker articulator marked a shift from the 19th century view of science, which aimed at universal principles, to the view of science of the 20th century, which pursued individual specificities. Around 1920, Hallʼs conical theory and Monsonʼs spherical theory appeared, but they sought the universal principle of the past, and the articulator they presented was the mono-condylar articulator that Bonwill denied. The trajec tory of the development from Bonwill to Walker is inherited by Gysi's Wippunkt articulator and the adaptable articulator. Gysi presented the axis theory as a means of analysis corresponding to individual specificities, but it was not taken up in the United States. Hanau's Model H articulator eradicated Gysiʼs adaptable articulator and dominated US prosthetic clinics for half a century. McCollum found a hinge axis with a slight opening when the jaw was naturally dropped open using a face bow, which led to a clue to a clinical solution to occlusal elevation on the articulator. In addition, McCollum pursued jaw movements, including lateral movements, and created the articulator Gnathoscope and the jaw movement scriber Gnathograph, which gave birth to the Gnathological School. Postwar gnathology caused a half-century whirlwind by many gnatholo gists, including Stuart, Stallard, and Thomas, but unknowingly transformed it into an occlusal theory with artificial final abdication as the ideal mandibular position. There is also a flaw in the articulator known as the fully adjustable articulator. Returning to the origin of the adjustment mechanism corresponding to each special case, we tried to re-evaluate the gnathology based on the fully adjustable articulator devised by the author.

In recent years, the cost of manufacturing prosthetic devices has increased due to soaring prices of palladium and gold, and as a result, health insurance financing is under pressure. As one countermeasure, a dental CAD-CAM hybrid resin was adopted in 2014 as a treatment option only for premolar crown restorations. In 2020, the indications for this hybrid resin were expanded to the maxillary and mandibular first molars. This enabled crown restoration for metal allergy patients or patients with esthetic demands, and we were able to respond to the increasing prices of precious metals. Considering the long-term prognosis, however, it is unknown whether hybrid resin crowns have optimal mechanical properties as an alternative material for molar crown restoration. In comparison with noble metals, CP-titanium and titanium alloys (Cp-Ti and Ti alloys) are inexpensive metals that have mechanical strength similar to that of Type 4 gold alloy. Laboratory techniques for dental gold alloys can be also applied for Cp-Ti and Ti alloys. Thus, cast crowns made with Cp-Ti and Ti alloy became covered by national insurance for medical devices in 2020. However, titanium casting requires complicated procedures with technically sensitive points. Therefore, application of CAD-CAM for the fabrication of Cp-Ti and Ti alloy prosthetic devices may be a solution to the problems in titanium casting. The present review proposes adopting CAD-CAM for the fabrication of titanium crowns under national insurance coverage in order to stably supply highly accurate titanium crowns to dental professions. 【The Journal of the Academy of Clinical Dentistry 40（3）：231-237，2020】

We report good results with the split crest and guided bone regeneration (GBR) using interconnective porous hydroxyapatite ceramic (NEOBONE^®) in a patient with abnormal alveolar bone resorption in the anterior region of the upper jaw. A 59-year-old female was referred to our hospital with a chief complaint of tooth mobility in the anterior region of the upper jaw. Vertical bone resorption in the right upper canine, right upper lateral, and left central incisor areas was remarkable. Mobility of those three teeth was noted and they were extracted. The patient wished for implant treatment though postoperative computer tomography results showed lack of bone mass in the anterior region of the upper jaw and we considered that bone augmentation would be needed before inserting the implants. Bone augmentation of the right and left upper central incisor parts was performed with the split crest, while GBR was used for the right upper canine part using the transplant material mixed with NEOBONE^® , autologous bone and blood. After confirming bone formation in the defect, three endosseous implants were inserted using fabricated final superstructures. For abnormal alveolar bone resorption in the anterior region of the upper jaw, a combination of form assignment and bone filling materials was easy to perform for use with the split crest and GBR. In comparison with other cases of bone augmentation, the risk of complications was considered to be reduced.

The purpose of this study was to investigate the tensile bond strength of various commercially-available dental luting cements to the mirror-polished surface of pure titanium compared to those of the surface of Ag-Pd-Cu-Au alloy and gold alloy. Flat surfaces of the three different types of metallic dental materials (JIS Grade 2 Titanium, 12 ％ Ag-Pd-Cu-Au alloy and Type 3 gold alloy) were mirror-polished, surface treated and bonded the stainless steel rod using either of resin-based composite luting cement [Panavia^® V5 (Kuraray Noritake Dental)], adhesive resin-based composite luting cement [RelyX^TM Ultimate (3M ESPE)], 4-META/MMA-TBB luting cement [Super Bond^® (Sun Medical)], and conventional glass-ionomer based luting cement [HY-Bond GlasIonomer CX (Shofu)]. For Panavia V5, either of Clearfil^® Ceramic Primer Plus (Kuraray Noritake Dental) or Alloy Primer (Kuraray Noritake Dental) was applied to the polished metal surface before cementing. Scotchbond^TM Universal Adhesive and V-Primer was applied before using Rely-X Ultimate and Super Bond, respectively. The different application methods of Super Bond on tensile bond strength was also investigated. V-Primer / Super Bond indicated the greatest bond strength than the other adhesive for 12％ Ag-PdCu-Au alloy. Although V-Primer/Super Bond showed the highest bond strength in both Type 3 gold alloy, the obtained strength was significantly lower than that for 12 ％ AgPd-Cu-Au alloy. For pure titanium, application of the mixture of Quick Monomer (5％ 4-META + 95 ％ MMA) and Catalyst V (TBB-O) prior to adhering using Super Bond obtained the enhancement of bond strength. Within the limitation of this study, it can be concluded that the effect of metal priming agent/luting cement to the mirror-polished dental metallic material depends on the type of metallic material.

In dental practice, we often encounter patients who present with difficulty in opening their mouths. Trismus not only interferes with dental treatment, but may also indicate a life-threatening and urgent general condition. Based on the etiology, trismus is classified into inflammatory, neoplastic, arthritic, traumatic, muscular, cicatricial, and neurological. Inflammatory trismus is the most common, followed by trismus due to TMJ disorders. In addition, there are various other potential causes; thus, it is necessary to diagnose and treat the cause accurately. If the results of the treatment for the initial diagnosis are not satisfactory, it is necessary to reassess the clinical symptoms and consider the possibility of a different disease. In order to provide safe and reliable dental treatment, it is necessary to diagnose the cause of the trismus and administer the appropriate treatment.

The absence of peri-implantitis is essential for the successful long-term maintenance of implant prostheses. Therefore, periodic maintenance care after implant treatment is important, and it should focus on prevention and early detection of peri-implant mucositis. As patients age, the quality of self-care declines. Capitalizing on the advantages of implant prosthesis, it is effective to remove the superstructure and provide professional care. In this paper presented are specific procedures, including examination before removal of the superstructure, inspection of self-care and cleaning after removal, cleaning and polishing of the superstructure, and cleaning of the remaining teeth. A case of a 77-year-old woman who was fitted with an implant superstructure more than 22 years ago. A case study suggests the effectiveness of removing the superstructure and performing thorough plaque control during maintenance.

A study was conducted to clarify the evaluation criteria for the success or failure of silicone impressions in the fabrication of mandibular full dentures provided that the objective of the final impression is to obtain sound fit with the crest of the mandible and surrounding tissues. The evaluation criteria were set based on three characteristic findings from the fitting test on the mucosal surface of the stable, functioning mandibular full dentures. Impressions with a single silicone impression material were considered the most suitable for the ease of evaluation of the impression surface, and the impression method of the Biofunctional Prosthetic System (BPS) was used as a control. The results showed that single-layer impressions tended to be undermaintained, and the denture border design of individual trays was important to compensate for this. We also found that the evaluability of the impression surface was improved by medium-flowing silicone impression material and by considering the color compatibility of the silicone and the personal tray. The present study concluded that practicing a single-layer impression with a single silicone impression material using an individual tray made in accordance with the mandibular suction mechanism would lead to a sound fit by fullfilling the three characteristics through the use of adaptive testing during the entire denture manufacturing process.

OHIP-14 The patient presented with a chief complaint of ill-fitting denture and masticatory disturbance by loss of the posterior occlusion. An intraoral observation found posterior occlusal support lost and the relation of the front teeth which originally was assumed to be the angle class III. The maxillary left anterior teeth, the abutment of the old denture, presented with mobility and plaque control was poor. Due to the patientʼs medical history of apical hypertrophic cardiomyopathy, the surgical invasion had to be minimized and a resilient telescope overdenture was designed preserving the remaining teeth. After confirming occlusal stability by treatment denture, the final prosthesis was fabricated based on the occlusion of the treatment denture. The score of OHIP-14, which evaluates QOL, improved and stabilized from 44 at the initial examination to a score of 13, but deteriorated to a score of 29 one year later. The implants placed in advance were employed in rescue, helping the score improve to 6. Currently, the dentures, the implants, and the abutment teeth are in stable condition, and the OHIP-14 score remains good, which contributes to the improvement of the patient's QOL.

One of the problems limiting the indications for implants is the problem of insufficient bone mass in the defect. There are two types of bone defects: vertical and horizontal. The bone deficiencies are often caused by bone resorption associated with dental disease, and by anatomical morphology, such as the lowering of the maxillary sinus floor. Autologous bone grafting, sometimes in combination with grafting with bone allograft is employed as preparation for implant treatment involving the bone defect. The choice of osteogenesis technique varies according to the extent, morphology, situation and location of the bone defect. Since the surgical procedure using bone allograft involves bone substitutes, it is necessary to consider that removal of the bone substitute material during recovery treatment will be difficult if any unexpected post-infection occurs. For the maxillary molar defect with poor vertical and horizontal bone mass, we performed implant treatment using maxillary sinus elevation and guided bone regeneration (GBR) without bone substitutes.

Methods for improving esthetic problems caused by median diastema include orthodontic treatment, full-coverage all-ceramic restoration, laminated veneer restoration with partial cutting, and direct bonding. In the present case, when the enamel is sufficiently preserved, and considering the long-term prognosis, it is preferable to opt for enamel preservation. In this paper presented is a case of esthetic repair of median diastema by direct bonding with good results. A 51-year-old woman presented with a complaint of esthetic problems. The patient had been previously treated at another clinic, but repeatedly experienced crown detachment. A diagnosis of median diastema with mild rotation was made, and taking into account the patient's request, less invasive procedure of composite resin direct veneer repair was performed. Agreeable results were obtained in which the morphology and color tone were in harmony. This suggests that esthetic improvement of the median diastema can be achieved by composite resin restoration with enamel preservation.

More than 70％ of patients who visit to the dental office have temporomandibular joint (TMJ) symptoms such as TMJ noise, mouth opening limitation and pain in the masticatory muscles and TMJ area, often with internalized symptoms of clenching and bruxism grinding. We dentists cannot avoid this point. In papers and case reports on IIIa-with reduction and IIIbwithout reduction of the TMJ disc disorder (type III), it is said that it is difficult to improve the improvement of joint disc repositioning and reduction. Therefore, we examined this issue by MRI and found many cases of improvement in articular disc displacement reduction. In this paper, we would like to report a case in which bilateral articular discs on the left side (IIIa) and the right side (IIIb) were repositioned. Changing the occlusion altered the anterior and lateral guidance, and the anteriorly displaced articular discs were repositioned and continued to function normally afterwards.