For anterior CAD/CAM resin composite crown, better aesthetics are produced by using a gradation block including enamel, dentin and transition color. In case selection, sufficient clearance and retention are expected. Abutment color should be same as a natural tooth color, and stable occlusal support of the molar region are recommended for safety use. For tooth preparation, simple abutment shape with a smooth surface, and a clear deep chamfer finish line are recommended. In the bonding procedure, it is required to apply alumina air abrasion and silane-containing primer treatment to the inner surface of the crown after try in. For abutment tooth, all contamination and temporary cement should be removed before bonding procedure. After perfect cleaning, tooth primer will be applied and adhesive resin cement should be used. By surely performing these treatments, safe and secure dental care can be established.

CAD/CAM crowns were first covered by the insurance for premolars in April 2014, followed by molars and then anterior teeth in September 2020. CAD/CAM crowns have become an option for single crown prostheses.

A clinical evaluation of CAD/CAM crowns placed on 17 anterior teeth showed no crown loss after an average of 2 years and 8 months.

To improve the long-term survival rate of CAD/CAM crowns, it is necessary to ensure that the clinical procedure is based on the following four points: selection of a safe case, appropriate preparation for abutment tooth in the shape and volume, design to enhance adaptation, and bonding procedure. The inner surface of the crown is preferable to be abraded with alumina at 0.2 MPa, cleaned with phosphoric acid, application of ceramic primer containing silane coupling agent and MDP, and then bonded with resin cement.

The application of CAD/CAM crowns in dental health insurance in Japan began in 2014 with the premolars. The Dental Service Problem Committee of Japan Prosthodontic Society had constituted the “clinical guidelines for CAD/CAM crown covered by health insurance 2014” in 2014 and has continued to show the details of the prosthodontic treatment policy for the CAD/CAM crown to the society members on the website and to other dental professionals through seminars related to the revision of dental fees. In response to the expansion of insurance coverage to molars and anterior teeth, the “clinical guidelines for CAD/CAM crown covered by health insurance 2020” was produced again in 2020. This commentary summarizes the outline of the guideline 2020, which has been significantly revised based on the guideline 2014.

The health insurance system in our country has covered non-metallic material prostheses. Therefore, a dentist can perform allergenic metal replacement with a small financial burden to a dental metal allergy patient suffering from skin or mucosa disease. Although numerous reports have shown that allergenic metal replacement can relieve skin or mucosa symptoms, there are some cases wherein allergenic metal replacement does not alleviate the symptoms. In such cases, it is possible that the examination, diagnosis, and/or treatment are flawed. This article suggests and demonstrates the efficacy of an exemplary and ideal examination, diagnosis, treatment plan, and consultation for dental metal allergy patients. This article complements a previous article “With The Aim of Treatment Guideline Development For Dental Metal Allergy and Related Diseases (2016)”.

Purpose: In the 2016 dental fee revision, prosthetic crown shade selection tests, denture chewing function tests, and tongue pressure tests were included in Japanese health insurance. Therefore, the kinds of functional tests performed in the latest specialist case report papers were investigated.

Method: Thirty-nine specialist case report papers published in Vol. 13, No. 1 (January 2021) to Vol. 13, No. 4 (October 2021) of the Journal of the Japan Prosthodontic Society and their status of description of prosthetic-related functional tests were investigated.

Results: As for masticatory function tests, 14 (36%) performed one of the three types of subjective evaluation (foods that can be ingested), and 10 (26%) used gummy jelly for objective evaluation. The occlusal pressure (force) test used prescale in 6 (15%) and bite eye in 2 (5%). As for other tests, there were only a few tests related to pronunciation and swallowing. One of the three types of satisfaction evaluation was performed in 10 (26%). The most common was OHIP-J as a QOL evaluation, with 25 (64%).

Conclusion: It was found that some prosthodontic-related functional tests were performed. The QOL evaluation was performed in 64%, but the subjective masticatory function evaluation (36%), the objective masticatory function evaluation (26%), and the occlusal pressure test (20%) were rarely performed.

Patient: The patient was a 54-year-old woman, with the chief complaints of esthetic dissatisfaction in the maxillary anterior region and difficulty in chewing due to bilateral missing molars. Objectively, a decreased vertical dimension of occlusion (VDO) and imbalanced occlusal plane were observed. The patient was willing to receive a removable denture treatment. Implant-supported fixed prosthesis and fixed partial denture (FPD) treatments were planned, in addition to restoring VDO.

Discussion: The patient has been recalled periodically since the final prosthesis was delivered. The patient was satisfied with the treatment without any specific problems, such as fracture or detachment, during the 5-year follow-up period.

Conclusions: The main complaint could be solved by the implant-supported fixed prosthesis and FPD treatments by increasing the VDO, resulting in high patient satisfaction.

Patient: A 70-year-old man visited our hospital complaining of poor esthetics and difficulty in mastication due to the incompatibility of a provisional restoration placed for a missing maxillary anterior tooth. After occlusal elevation, a maxillary 6+5 cross arch bridge (shortened dental arch), composite resin restorations for mandibular anterior teeth, porcelain-fused-to-metal restorations for mandibular premolars, and a removable dental prosthesis in the right mandibular molar region were provided.

Discussion: After 3 years and 3 months, plaque control was very good, and no major problems were observed. The patient’s oral-related QoL improved after the treatment.

Conclusions: Thanks to appropriate occlusal elevation and anterior guidance, functional recovery and predictability were achieved. Moreover, the application of a shortened dental arch to the maxilla resulted in an oral environment with less discomfort and a high degree of satisfaction.

Patient: A 79-year-old woman visited our hospital for a tumor of the left alveolar gingiva that was diagnosed as stage IV squamous cell carcinoma (T4aN0M0) and underwent maxillofacial surgery, which included partial maxillectomy and partial thickness skin transplantation. An immediate surgical obturator (ISO) with full arch dentition was used. The ISO was adapted to the patient immediately after the surgery and used as a treatment denture. Using the ISO, the patient was able to ingest regular food, the same as taken before the surgery. A final prosthesis was installed at 8 months after surgery.

Discussion: The ISO reduced the period of lower oral dysfunction. Reconstructing the dentition of the prosthesis improved esthetics as well as masticatory function.

Conclusions: An ISO lessens the psychological burden of patients after surgery by improving quality of life and achieving early reintegration into society.

Patient: A 75-year-old male patient complained of his dentures easily coming off and associated eating difficulties. His edentulous maxilla had a defect on the left side, for which he had undergone free flap reconstruction. His maxillary denture did not have enough retention. We extended the obturator to the undercut on the defect and fabricated a maxillary denture using a hollow obturator to improve the fit and retention of the denture.

Discussion: The good outcomes were attributable to: retention and stability of the maxillary denture provided by the obturator extended to the undercut on the defect; use of a hollow obturator; and improved retention by reducing the denture weight.

Conclusion: In this edentulous patient who underwent free flap reconstruction of a defective jaw, a satisfactory treatment outcome was obtained by using an undercut on the defect for denture retention and using a hollow obturator.

Patient: A 75-year-old male visited our hospital with a chief complaint of eating difficulties caused by unstable mandibular complete denture. This patient had severe mandibular tori and undercuts that made the mandibular complete denture unstable with lack of border sealing and poor retention. After surgical removal of his mandibular tori, new complete dentures were set using a general method.

Discussion: Stability and retention of the dentures were achieved by adequate denture base forms, which were obtained by the usual clinical procedures after surgical removal of the mandibular tori. This should have contributed to the functional rehabilitation.

Conclusion: Surgical pretreatment should be considered for successful outcomes in the case of severe mandibular tori and slight atrophy of the residual ridges.

Patient: The patient was a 61-year-old female with the complaint of teeth mobility. The patient was diagnosed with masticatory disorders due to teeth mobility caused by severe periodontitis, and treatment dentures were placed at the same time as extracting those teeth with severe mobility. After periodontal surgery, overdentures with magnetic attachments for the maxilla and mandible were inserted. The masticatory function was improved, and the mandibular position and periodontal tissues of the remaining teeth were stable five years and eight months after the treatment.

Discussion: It is considered that not only periodontal treatment but also the reduction of lateral force to abutment teeth by correction of the crown-root ratio contributed to the reduction in tooth mobility by using overdentures.

Conclusion: A long-term favorable outcome was obtained by appropriate prostheses.

Patient: The patient was a 67-year-old female complaining of masticatory disturbance caused by poor retention. Signs of combination syndrome were observed, so the mandibular anterior teeth were restored by metal coping and a treatment denture was fabricated. After being treated with the treatment denture, metal dentures for the upper and lower jaws were completed as the final prostheses.

Discussion: The overdenture provided stability in the occlusal position and denture, and improved satisfaction with the denture and masticatory score. In addition, by applying the FGP technique and occlusal pressure impression using a duplicate denture made from a treatment denture, it was considered that the occlusal contacts were harmonized with the patient’s mandibular movement.

Conclusions: Treatment with an overdenture was effective for combination syndrome prosthodontic treatment including an implant-supported fixed denture.

Patient: The patient was a 43-year-old female who visited our hospital requesting a second opinion for missing anterior maxillary teeth. Tooth extraction due to significant gingival defect, alveolar ridge augmentation and installation of a provisional restoration were performed, followed by later treatment with a fixed prosthesis.

Discussion: A zirconia bridge, which was both esthetically good and biocompatible, was fabricated after confirming function, esthetics and cleanability using the restoration of the residual ridge and provisional restoration. It was considered that a long-term stable prognosis was obtained.

Conclusion: Various problems causing a residual ridge after tooth extraction require an appropriate diagnosis and treatment planning aiming for a clear treatment outcome.

Patient: The patient was a 63-year-old male who complained of masticatory disturbance and esthetic problem due to the loss of a bridge in the mandibular left posterior region and extensive tooth wear. To correct the decreased vertical occlusal dimension and the lack of prosthodontic space, a treatment denture was used to increase the dimension. Fixed and removable combination prosthodontic management was delivered as the final treatment.

Discussion: In this case, the treatment denture was used to increase the vertical occlusal dimension and the patient’s adaptation was confirmed. It is considered that occlusal reconstruction suitable for the patient was completed safely and surely.

Conclusions: It is considered that increasing the vertical occlusal dimension to obtain prosthodontic space may be effective for reconstructing oral function and esthetics in partially edentulous patients with extensive tooth wear.

Patient: A 77-year-old edentulous male patient complained that his complete denture easily fell out when eating and talking. A new denture was fabricated to modify the shape of the polished surface and position of the artificial teeth.

Discussion: It is considered that a good prognosis was achieved by functionally harmonizing the denture form with the tongue and the perioral muscles, such as by using piezography for taking impressions of the denture space.

Conclusion: Fabrication of a new denture with the position of artificial teeth and shape of the polished surface determined by piezography achieved a favorable prognosis in this case.

Patient: A 54-year-old woman visited our clinic with the chief complaint of masticatory disturbance due to mobility and pain of the maxillary anterior teeth. Decreased occlusal support area of molars, irregular occlusal plane, and restriction of mandibular movement were found. An objective evaluation of mandibular movement was performed using the Gothic arch tracing method at each stage of treatment. After improvement of mandibular movement was obtained, occlusal reconstruction was performed, including a maxillary cross-arch bridge, reflecting information on the provisional restoration.

Discussion: It is considered that the improvement of mandibular movement and the stability of the intercuspal position led to long-term stability of the final prosthesis. At the time of occlusal reconstruction, not only a subjective evaluation by the doctor and the patient but also an objective evaluation of mandibular movement is important.

Conclusion: The Gothic arch tracing method was effective for objectively evaluating mandibular movement during occlusal reconstruction.

Patient: A 68-year-old male patient visited our hospital with the chief complaint of difficulty in mastication due to teeth mobility. At the first visit, most of the upper teeth exhibited periodontitis but the vertical dimension was maintained. The upper teeth were extracted, and an immediate complete denture was provided. After a six-month healing period, eight implants were placed and immediate temporization was performed. Another six months after the immediate restoration, a final impression was made and the vertical dimension was reproduced by connecting the temporal restoration with a working cast.

Discussion: To date, the superstructure, soft tissue, and hard tissue surrounding the implants remain in good shape. To maintain the good condition, it is necessary to follow up the occlusal position on a regular basis.

Conclusion: In this case, a successful outcome was obtained due to the minimum shifts of the dental arch and vertical dimension by sequential prosthetic procedures.

Patient: A 73-year-old woman visited our dental clinic with the chief complaint of difficulty on mastication caused by unsteadiness of dentures. There was no occlusal support in the molar region. After setting an appropriate occlusal plane, an overdenture with a stud attachment was attached to the maxilla, and a final prosthetic device with a removable denture using an extracoronal attachment was attached to the mandible.

Discussion: An overdenture on the maxilla contributed to denture stability by attaining adequate support and balanced occlusion.

Conclusion: It is considered that the stability of the denture was obtained by attaching the metal denture after proper pretreatment, which led to a good evaluation and long-term maintenance.

Patient: A 67-year-old man visited the hospital with the complaints of denture pain and inability to bite. Therefore, therapeutic dentures were manufactured to correct the occlusal plane and the adjustment curve. The occlusal adjustment was repeated to obtain stable tapping at the centric relation. Since the occlusion was stable and it became possible to chew with the therapeutic denture, the final dentures were manufactured by following the morphology of the therapeutic dentures as much as possible.

Discussion: By adjusting the occlusal position by tapping at the centric relation of the chewing with therapeutic dentures and modifying their morphology, it was possible to manufacture a final prosthetic device with high predictability, and to improve oral-related QOL and satisfaction with the denture.

Conclusion: Good results were obtained by manufacturing prosthetic devices while confirming the stability of occlusion using therapeutic dentures.

Patient: A 59-year-old female visited our hospital with a chief complaint of difficulty in chewing due to pain of the maxillary anterior teeth. Root fractures of the maxillary anterior teeth and attrition of the natural teeth were observed. We suspected excessive occlusal force due to bruxism, and performed implant treatment with an oral appliance during and after the treatment period.

Discussion: It was suggested that good progress was obtained by confirming that the patient could wear the oral appliance before beginning the implant treatment and could keep wearing the oral appliance after the installation of the final prostheses.

Conclusion: Force control during and after the treatment was important for this patient.

Patient: The patient was a 20-year-old female. In this case, the maxillary four anterior teeth had to be extracted due to root resorption caused by impacted canines. After retraction of the impacted upper canine to the position of the central incisors, a porcelain-layered zirconia fixed dental prosthesis was used to restore esthetics and function. Good results were obtained for more than three years.

Discussion: Many cantilever resin-bonded fixed dental prostheses are clinically applied. In this case, the position of the maxillary central incisor was the canine tooth, which had a high root ligament bearing capacity, resulting in a good prognosis.

Conclusion: It is suggested that a cantilever fixed dental prosthesis can avoid overtreatment and provide long-term stable esthetic and functional recovery.

Patient: The patient was a 60-year-old woman with the chief complaint of difficulty in chewing. She had been receiving medical treatment for rheumatoid arthritis. Open bite caused by deformation of the temporomandibular joint (TMJ) and TMJ pain on chewing were observed. An oral appliance (OA) with a metal framework was used to reconstruct the appropriate occlusal contact and to improve masticatory function because it can easily adapt to future changes in occlusal condition caused by the worsening of rheumatoid arthritis.

Discussion: Placement of the final OA may have reduced the stress on TMJ, thus relieving TMJ pain.

Conclusion: In this case with open bite caused by deformation of TMJ accompanied with TMJ pain and masticatory difficulty, an OA with a metal framework was applied. The symptoms were alleviated and the patient was satisfied with the treatment.

Patient: A 76-year-old male presented to our clinic complaining of pain in the mucosa underlying his denture base when chewing, and of the accumulation of food residue.

Discussion: Application of the flange technique using duplicate dentures led to the establishment of stable dentures. Information regarding the patient’s existing dentures also helped to determine the arrangement of the artificial teeth and polished surface form. In such cases, pain in the mandibular mucosal surface might improve after applying soft relining material.

Conclusion: Application of the flange technique using duplicate dentures and resilient relining material effectively treated this case of severe alveolar crest absorption.