Implant overdenture (IOD) is a field in which evidence has been rapidly accumulating since around 2000, when McGill consensus and York consensus were announced. There are many variations of IOD, including mandibular 2-IOD, which is an established technique, 1-IOD, mini-IOD using mini-implants, and different types of attachments. The clinical applications of maxillary IOD and Implant assisted removable partial denture (IARPD) for partial defects has been also increasing. In this paper, we would like to introduce the latest evidence on IOD and IARPD from about 200 clinical studies since 2000, and summarize what we know so far according to the following items.

There is no doubt that the implant overdenture (IOD) is a dental prosthetis with a marked improvement effect for many edentulous people. However, on the other hand, its clinical application has barriers such as 1) economic, 2) psychological, 3) biological and 4) time cost.

These barriers correspond to the denominator part of the concept of Value-Based Dentistry (VBD): Value = Quality/Cost. Therefore, if these “costs” can be reduced, the patient’s Value = benefit will be even greater, and the IOD will become a more popular prosthetic option.

In this paper, IOD cases intended for VBD concept are presented with clinical procedures.

In today’s aging society, we need treatments that protect our teeth for a long time and function more comfortably.

Under such circumstances, It seems that it is time to re-question how to view the missing dentition and maintain it better.

Patients often want a prosthesis that chews well and feels less discomfort. However, will the prognosis be good if the prosthesis meets the demand? The diagnosis of the missing dentition and the selection of the prosthetic form should be led by the operator while listening to the patient’s voice. Also, regarding the application of implants, we would like to aim to maintain the remaining teeth for a long period of time, considering the nature of the missing dentition. While responding to the trends of individual defects, I would like to think about what kind of prosthesis should be provided.

In this paper, the change of mandibular position and occlusal contacts as a result of a pathological condition of the temporomandibular joint (TMJ) are illustrated with its management. There are two pathological conditions of TMJ disease. One is a pathological condition with reversible change of mandibular position and occlusal contacts such as abnormal tension of the masticatory muscles and/or inflammation of the TMJ etc. The other condition resulting in irreversible change can be e.g. degenerative joint disease of the TMJ, idiopathic/progressive condylar resorption etc. When the pathological condition of the masticatory system is a reversible phenomenon with temporarily an occlusal change, application of irreversible treatments such as occlusal equilibration etc. will be causing serious damage like an artificial occlusal problem. On the other hand, when the pathological condition of the TMJ is an irreversible phenomenon, the evolution is uncertain and no guideline for proper timing of intervention and appropriate treatment methods exist. This paper aims at providing a good opportunity to organize the reader’s knowledge of the management of a change of mandibular position and occlusal contacts following pathological condition caused by TMJ and masticatory muscle.

Diagnosis and treatment of malocclusion in patients with temporomandibular disorders (TMD) must be performed with understanding the diversity of malocclusions observed in patients with TMD, because there are various malocclusions such as those acting as the cause of temporomandibular disorders and secondary malocclusions caused by the pathological changes of temporomandibular joints (TMJ) and muscles in TMD patients. In the present article, the outline of countermeasure against malocclusions in consideration of the state of TMJ and masticatory muscles was explained. The broad viewpoint in consideration of influences of condylar position in TMJ and activities muscle-nerve system on occlusion is required for daily clinical practice of general dentistry not limited to TMD. Therefore, understanding how the occlusal treatment in TMD should be will also be useful for skills in occlusal treatments for general patients in dentistry.

Purpose: Discouraging microbial adhesion to dental prosthetics is an effective means of preventing secondary caries and opportunistic infections. We developed prototype resins containing surface reaction-type pre-reacted glass-ionomer (S-PRG) filler for use in facing crowns with the objective of inhibiting microbial adhesion to facing crowns and plaque formation.

Methods: In this study, in vivo tests of the antiplaque effect of these resins and in vitro tests of their effect in preventing the adhesion of Streptococcus mutans and Candida albicans were carried out, and the flexural strength, Vickers hardness, and toothbrush wear were also investigated.

Results: The flexural strength and Vickers hardness of all the test materials met the ISO criteria. In toothbrush wear tests, increasing the S-PRG filler content made no great difference to the amount of wear. In the antiplaque tests, plaque adhesion was more suppressed as the S-PRG filler content increased. In the microbial adhesion test, increasing the S-PRG filler content made no great difference when the test materials were immersed in distilled water. However, the Streptococcus mutans and Candida albicans counts both decreased when the test materials were immersed in saliva or subjected to thermal cycling.

Conclusions: Materials with an S-PRG filler content of 9.4–18.8 wt% had antiplaque properties and excellent physical properties. These results also suggest that they may exert long-lasting antimicrobial adhesion properties.

Purpose: Although there are short-term clinical reports of CAD/CAM-produced composite resin crowns using hybrid resin blocks for premolars, a long-term survey under certain conditions of intracrown pretreatment is needed because variations were seen in previous reports. The purpose of this study was to evaluate the longevity of premolar CAD/CAM-produced composite resin crowns installed under certain conditions of pretreatment.

Methods: During the 6 years from April 1, 2014 to March 31, 2020 at the Departments of Prosthodontics and Implantology, Fukuoka Dental College Medical and Dental General Hospital, we performed a retrospective study of premolar CAD/CAM-produced composite resin crowns placed by 16 dentists with at least three years of clinical experience. The pretreatment for luting was divided into two groups: one in which all pretreatments of alumina sandblasting, phosphoric acid treatment, and silane treatment were performed (guideline compliance group), and the other in which at least one of the treatments was not performed (guideline non-compliance group). CAD/CAM-produced composite resin crown, coronal survival and related factors were examined using the Kaplan-Meier method and Cox proportional hazards analysis.

Results: The 6-year cumulative survival rate was 93.6% and the success rate was 88.8%. The 6-year cumulative survival rate was 92.7% in the guideline compliance group, which was significantly higher than 79.5% in the guideline non-compliance group. Regarding factors affecting survival time, the Cox proportional hazard analysis found that the complete or pretreatment of the adhesive pretreatment had a significant relationship with the survival time.

Conclusion: Adhesive pretreatment for luting is important for obtaining long-term longevity, suggesting that premolar CAD/CAM-produced composite resin crowns may be sufficient for clinical use.

Patient: The patient was a 74-year-old female who complained of lack of mandibular denture stability and inability to properly masticate. In the mandible, severe resorption of the alveolar ridge was observed. After pre-prosthetic treatment for the remaining teeth, upper and lower complete dentures were fabricated as diagnostic dentures. Finally, the implant-supported overdenture with two implants was placed on the mandible.

Discussion: It is considered that pre-prosthetic diagnosis of the prosthetic space by using diagnostic dentures enabled steady progress.

Conclusion: The restoration with implant-supported overdenture was effective in improving the masticatory and oral health-related QOL in the edentulous patient with severe ridge resorption of the mandible.

Patient: The patient was a 54-year-old man who complained of tooth hyper-mobility and difficulty in chewing. The mobility of the remaining teeth ranged from M1 to M3 due to severe alveolar bone resorption, and the hyper-mobility induced masticatory disturbance. All of the remaining teeth that were diagnosed as having a poor-prognosis were extracted, and five implant bodies were placed in the maxilla and four implant bodies were placed in the mandible. Implant-supported full-arch dentures were then inserted. The patient was satisfied with the function and esthetics even 3 years and 7 months after treatment.

Discussion: Establishing stable oral function without early re-treatment due to remaining teeth troubles contributed to the patient’s satisfaction.

Conclusion: A patient complaining of masticatory disturbance due to teeth hyper-mobility was successfully treated with implant-supported fixed dentures after extracting poor-prognosis teeth.

Patient: The patient was a 71-year-old female who had esthetic problems and decreased occlusal height due to anterior bridge failure and attrition and masticatory disturbance due to molar defects. Vertical dimension increase was performed using provisional restorations with reference to the diagnostic wax pattern. Esthetic restoration was achieved through prosthetic and restorative treatment with occlusal support for the molar area and appropriate guidance.

Discussion: The final prosthesis was fabricated after sufficient functional and esthetic examination using provisional restorations, which may have resulted in good long-term results.

Conclusion: The provision of occlusal support and appropriate anterior guidance is effective in maintaining good function in the long term.

Patient: The patient was a 55-year-old male with a chief complaint of difficulty in eating. A fixed bridge and metal crowns on the mandibular molars had become detached due to dental caries. Retention and fit for the alveolar ridge of the mandibular denture were poor. The patient was diagnosed with masticatory dysfunction, loss of retention (which was caused by loss of retention of the fixed prosthesis due to secondary caries) and poor retention of the denture. The fixed prostheses and removable partial denture were replaced. To improve the denture support, root attachments and caps were used. Metal artificial teeth were used for insufficient denture space.

Discussion: Long-term stability of the denture occlusion and teeth may have been achieved by using root attachments and metal teeth in the insufficient clearance.

Conclusion: Masticatory dysfunction was reduced by the denture using metal teeth and attachments in a partially edentulous patient with reduced denture space.

Patient: The patient was a 59-year-old woman. Her chief complaint was masticatory disturbance and esthetic dissatisfaction due to incompatibility of dentures and dislodgement of multiple fixed prosthodontic devices. Infraocclusion due to loss of occlusal support in the molar parts was also observed. After performing bite-raising by using a treatment denture and confirming stability of the mandibular position, prosthodontic treatments with dental implants were performed.

Discussion: In the present case, occlusal support in the molar parts with an appropriate occlusal vertical dimension improved the infraocclusion, and a stable postoperative course was obtained.

Conclusion: Masticatory disturbance and esthetic dissatisfaction were improved by bite-raising with a treatment denture and by occlusal support with dental implants.

Patient: A 50-year-old woman was admitted to our hospital complaining of masticatory disturbance due to denture movement, pain of a maxillary full arch bridge and poor esthetics of the mandibular denture. Implant treatment with immediate loading was selected for the maxillary teeth after extracting the hopeless teeth. A fixed prosthesis with dental implant was applied for the mandibular molars, and the mandibular anterior teeth were esthetically improved with all-ceramic crowns.

Discussion: This treatment improved the patient’s chief complaint and the oral health-related quality of life was improved.

Conclusion: The implant prosthesis and fixed prosthesis were effective in resolving esthetic dissatisfaction and masticatory disturbance.

Patient: A 49-year-old man complained of frequent fracture and unstableness during use of maxillary complete dentures. Inadequate shape of the dentures, inappropriate maxillomandibular relationship, and instability of the intercuspal position were observed. The maxillomandibular relationship and occlusal position were recovered using treatment dentures, and definitive dentures were set after reassessment of his oral conditions.

Discussion: An appropriate maxillomandibular relationship was obtained by using the treatment dentures. The gothic arch tracing method was useful for confirming the proper mandibular position. The distribution of occlusal force on his occlusal arches by the relevant occlusal position, the proper design and the esthetics of the dentures were fundamental for the function and stability of the dentures.

Conclusion: An appropriate maxillomandibular relationship and occlusal parameters are important for favorable clinical outcomes of denture treatment.

Patient: The patient was a 47-year-old female. She visited the prosthodontic clinic of Tokyo Medical and Dental University with a chief complaint of esthetic disorders in the anterior teeth and masticatory disorders in the molars. Loss of occlusal contacts in the posterior region and severe wear in the anterior region were causing masticatory dysfunction and esthetic impairment. Her chief complaint was resolved by bite-raising using a therapeutic denture and a provisional restoration. The final treatment was performed using removable partial dentures in the molar region and a fixed partial denture in the anterior region.

Discussion: Prosthodontic treatment for missing teeth provided stable occlusion in the molar region and eliminated the cause of anterior abrasion.

Conclusion: For this case with severe wear, esthetic and masticatory functions were recovered by bite-raising with a fixed prosthetic device in the maxillary anterior teeth and removable partial dentures in the missing teeth.

Patient: A 48-year-old male patient who underwent excision of a pleomorphic adenoma on the maxillary hard palate was diagnosed with a speech disorder due to postoperative palatal mucosal defects. Speech intelligibility improved following the installation of an obturator that covered the defect area.

Discussion: The patient’s speech intelligibility, which had been affected following excision of the pleomorphic adenoma, was improved with a fabricated obturator. Depending on the excision range, it may be important to select a reconstruction method that takes into consideration the articulation, mastication, and swallowing functions.

Conclusion: It was shown that in this case with postoperative palatal defects, speech intelligibility was improved by installing an obturator with a resin bed and the patient getting used to the obturator.

Patient: The patient was a 68-year-old female. The chief complaints were masticatory disturbance and poor esthetic appearance caused by inadequate removable partial dentures on the upper and lower jaws. She was also dissatisfied with the conspicuous appearance of her denture clasp. The chief complaints were resolved using hybrid resin facing metal fixed prostheses and telescopic crown-retained removable partial dentures.

Discussion: It is considered that the esthetics, functionality and periodontal tissue condition were improved by wearing telescopic crown-retained removable partial dentures.

Conclusions: Good esthetics and occlusal support were obtained by using hybrid resin facing metal fixed prostheses and telescopic crown-retained removable partial dentures.

Patient: The patient was a 67-year-old male with the complaint of discomfort when eating. The patient was diagnosed with masticatory disability due to tooth mobility caused by severe chronic periodontitis, and masticatory disability due to multiple tooth loss. After achieving occlusal support by multiple tooth extraction and immediate dentures, the final prosthesis treatment involved providing a telescopic crown-retained removable partial denture prosthesis.

Discussion: In this case, we attempted secondary stability of the remaining maxilla teeth using a telescopic crown-retained removable partial denture prosthesis. Acquisition of secondary stability by this prosthesis contributed to improvement of masticatory function and the patient’s satisfaction.

Conclusion: It was suggested that a telescopic crown-retained removable partial denture prosthesis improved masticatory function.

Patient: A 45-year-old man presented to the clinic with a complaint of difficulty in chewing due to dental caries. The maxillary right central incisor and mandibular right and left lateral molars had residual roots due to caries, and the functional cusp of the maxillary right and left lateral second molars was in contact with the mandibular ridge at the intercuspal position. Improvement of masticatory disorders was achieved by using a partial denture in which the mandibular anterior tooth incision and the posterior occlusal surface were covered with a zirconia framework to increase the occlusal height and correct the occlusal plane.

Discussion: Correction of the occlusal height and occlusal plane with a partial denture resulted in an improvement in masticatory disorders and an increase in maximum occlusal force.

Conclusion: A partial denture with a zirconia framework effectively improved masticatory disorders associated with reduced vertical prosthetic zone by improving masticatory function.