Implant prosthesis engages in the morphological formation of peri-implant tissue or the arrangement of abutments that have been untouchable for conventional prosthodontists. Furthermore, the advancement of computer technology makes possible a clinical implant design on the virtual space and its realization in the mouth. That means the inevitability of a different prosthetic stance on the design of implant superstructures. Along with this change, the traditional prothodontist’s working area has been decreasing.
In this article, we explain the prosthetic stance on implant superstructures in the esthetic zone by focusing on 3 target areas: the individual implants, the mouth, and the face. The design guide of implant superstructures is then presented.

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When patients who come to us have lost anterior teeth, their main concern is esthetic recovery. In the clinical reality of most anterior tooth loss cases, the remaining hard and soft tissues are insufficient to achieve an optimal esthetic result. This deficiency can be even more visible in multiple tooth loss cases. For both the patient and the practitioner to be esthetically and clinically satisfied with the results, it is first necessary to establish a clear treatment goal and then to manage peri-implant hard and soft tissues according to that goal. This paper will discuss the selection of appropriate treatment goals as well as clinical cases demonstrating three dimensional hard tissue management with GBR and soft tissue management for crown-bridge types of superstructures.

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The requirements for long-term performance of dental-implant-supported prostheses in the esthetic area have been summarized and organized. At present, the thicknesses of labial balcony and gingival are receiving attention as influential factors, and both need to be well maintained for thickness and volume.
In contrast, the factors of diagnosis and clinical approaches that are being responded to in each clinical case are not well organized. The purpose of this paper is to indicate the approaches to diagnosing the implant positions, using computer tomography (CT), and to reconstructing and maintaining the tissues based on long-term surveillance results.

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Selection of the proper fixture can lessen implant complications. A conical connection type of implant can reduce peri-implantitis and will therefore provide long stability. Implant prostheses manufactured from high strength material using CAD/CAM prevent fractures of the prostheses. Proper abutments concerning strength, diameter, length, and usage of submerged-type implants could lead to implant longevity.

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In regard to the esthetics of dental implant treatment, the positions of marginal gingival and interdental papilla, as well as long-term stability, are as important as in the restoration of natural teeth. But no matter how much research has been carried out on these concerns in the past two decades of the 1990s and 2000s, not a great deal has been learned. This research seems to consist of studies only on changes in appearance of the marginal gingiva and interdental papilla caused by the change of hard tissue around implants that occurred after insertion, already well-known in the 1980s. But what’s more important is the preservation and/or reconstruction of sufficient hard tissue for the implant site to ensure the esthetics of dental implant treatment. Many earlier reports suggested that it generally resulted in the esthetic restoration during implant treatment to maintain at least the hard tissue of 2 mm on buccal (labial) and lingual (palatal) implant sites, 1.5 mm between the implant and the natural tooth, and 3 mm between the adjacent implants. Furthermore, the inserted implants should be 3 mm apical to zeniths of the facial-gingival margins, but there are individual differences.

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Implant therapy has been widely used for fully or partially edentulous patients. Following the fundamental rules make it highly predictable, and thus it is a highly an effective option in various edentulous statuses. In more than a few patients who need prosthetic treatments, however, conventional manners are more appropriate because of the variety found in oral conditions. Furthermore, the social environment or demands of patients should be considered in decision making. A large difference between implants and natural teeth, which are surrounded by periodontal ligament, is dynamic behavior. This will theoretically make it impossible to evenly distribute occlusal load in a mouth having both teeth and implants. More consideration is required when providing implant prosthodontics to partially edentulous patients with periodontal complications remaining teeth. In this presentation, I would like to describe the criteria of various prosthetic treatments by showing cases of occlusal reconstruction.

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Purpose: The aim of this study is to clarify the difference between the masticatory function in at-risk conditions needing care and in otherwise normal elderly subjects. It also intend to determine the relationship between the masticatory function and each factor in the fundamental checklist.
Methods: The subjects were 134 elderly residents of town I in Hokkaido. Answers to the fundamental checklist and the results of a food intake questionnaire were obtained from the subjects. The remaining teeth of applicable subjects were counted, and for those with dentures the shapes of the removable dentures were analyzed, and a self-evaluation of denture satisfaction, suitability, pain, ease of mastication, esthetics, and ease of speech production was provided. The subjects were divided into two groups: at-risk and otherwise normal. All data from both groups were compared to analyze the correlation between each factor in the fundamental checklist and masticatory function.
Results: For the at-risk group, the average number of teeth per individual and the average masticatory scores were shown to be quite low, as were scores related to the suitability of upper dentures, to the external form of lower dentures, to the degree of denture satisfaction, and to the degree of ease in pronunciation. The masticatory score showed a weak correlation to the "life function," "motor function," and "oral function" factors of the fundamental checklist.
Conclusions: Continued improvement of oral function needs as a part of the preventive support of long-term care a kind of care that takes into consideration not only oral function, but also factors that affect the functioning of the entire body.

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Purpose: The purpose of this retrospective cohort study was to investigate the effect of maintenance care on periodontal conditions of abutment and non-abutment teeth at 5-year follow-up.
Methods: A total of 231 one patients were treated with rempval partial dentures (RPDs) at the Tohoku University Hospital from 1996 to 2005. Of the 231 patients, 108 who had agreed to undergo 5-year follow-up were examined. The RPD prognoses were categorized into three categories: successful (n = 63), remake (n = 35), and failure (n = 14). Among the successful subjects, 34 patients who received periodic maintenance were selected as study subjects and divided into two groups, M ≥ 4 (subjects who received periodic maintenance more than 4 times per year), and M ≤ 3 (received periodic maintenance 3 or fewer times per year). The variables analyzed were (1) O’Leary’s Plaque Control Record (PCR), (2) Pocket depth (PD), (3) Miller’s tooth mobility (TM), and (4) Bone resorption level (BRL). Periodontal conditions of remaining teeth at the follow-up clinical examination were compared with the results of the first examination when RPDs were inserted by using the Wilcoxon signed rank test.
Results: In the M ≥ 4 group, significant differences were not found in the 4 variables of the abutment teeth. However, non-abutment teeth showed significant improvement in PD and TM between the time of placement and 5 years later. In the M ≤ 3 group, the abutment and non-abutment teeth showed statistically significant deterioration in PCR, PD, and BRL, whereas significant improvement was found in the non-abutment teeth.
Conclusions: Maintenance care more than 4 times per year was effective to maintain good periodontal conditions for the wearers of PRDs.

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Purpose: The aim of this study was to examine the method of cutting a notch in the mouthguard sheet to maintain mouthguard thickness.
Methods: The material used in this study was a mouthguard sheet 3.8 mm thick. Two sheet conditions were undertaken: one was an original sheet, and the other was a notched sheet. They were formed using a vacuum former to heat the sheets until they hung 20 mm from the baseline. We measured the thickness of the mouthguard at the incisal area (cusp), center area, and cervical area using a measuring device. The difference of thickness by the measurement point and the sheet condition was analyzed by two-way ANOVA.
Results: The thickness of the center and cervical areas of the notched sheet was thicker than that of all measurement points of the original sheet (p < 0.01) on the anterior teeth region. On the posterior teeth region, the thickness of each measurement point statistically differed with significance from the original sheet and the sheet with notches (p < 0.05 or p < 0.01). The notched sheet was thicker than that of the original sheet (p < 0.05).
Conclusions: These results suggested that the mouthguard sheet with notches could maintain thickness of the mouthguard at the anterior and posterior teeth regions and thus might be effective in clinical use.

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Purpose: The aim of this study was to clarify osteological changes in the femoral epiphyseal region in ovariectomized rats with differing mineral consumptions. The bone tissues were assessed using 3-dimensional maps, bone mineral contents, and bone volume measurements. Data from microcomputed tomography with TRI / 3D-Bon BMD application software were also used.
Methods: A total of 48 rats were randomly distributed into three groups (n = 16 per group). The control rats, in Group 1, were subjected to a sham operation when 20 weeks old and given a normal diet. The remaining 32 rats were subjected to bilateral ovarectomy at the same age and divided into Group 2, ovariectomized rats on normal diet, and Group 3, ovariectomized rats on low-mineral diet. Each group began eating its prescribed diet at 20 weeks. Observations were made at 4, 8, 16, and 24 weeks on the respective diets.
Results: In the color scale 3-dimensional map of cancellous bone, high bone-mineral density was observed in sites found to be in contact with cortical bone, and middle and low bone-mineral density distributions were observed in the medullary cavity. Bone-mineral content of the cortical and cancellous bone was significantly decreased at 24 weeks in groups 2 and 3 compared to Group 1. Bone volume was significantly lower at 24 weeks in groups 2 and 3 than in Group 1.
Conclusions: This study demonstrated two things: (1) a mineral-deficient diet may decrease cancerous bone volume, which might be associated with estrogen deficiency as a result of ovarectomy, and (2) 3-dimensional maps may be useful in diagnosing osteoporosis and other diseases causing bone loss.

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Patient: After fixed partial dentures were removed with teeth extraction and placed dental implants removal in the mandible, a new complete denture was fabricated for the patient in another dental clinic. However, continous pain as he chewed gave him difficulty, and we fablicated a new complete denture with an impression technique using an individual tray made of clear resin to improve the difference of tissue displace-ability in my clinic.
Discussion: Because an impression technique of this kind is helpful to observe basal seat mucosa directly and to reduce high pressure on basal-seat mucosa, it is thought to be more effective in decreasing basal-seat mucosal pain in chewing than a traditional selective pressure impression would be.
Conclusion: An individual clear resin tray is effective in fabricating a complete denture with severe residual ridge resorption on the maxillae or mandibles, which have poor tissue displaceability.

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Patient: The patient was a 52-year-old female who complained of esthetic disturbance of the maxillary anterior teeth. Abutment teeth of a 4-unit upper anterior fixed-partial denture were diagnosed as pyorrheal and extracted. As a result, four upper incisor teeth were consecutively missing. She obstinately wanted to restore fixed restoration, and she did not to prepare approximal teeth. For the reasons stated above, implant restoration was selected for intermediate edentulous ridge.
Discussion: When restoration is done with fixed partial denture, preparation of the tooth substance is indispensable. In this case, implants were used for abutments, and approximal intact teeth were saved.
Conclusion: Approximate teeth for intermediate defects were preserved by shift from the conventional fixed partial denture to the implant restoration. Because the patient was satisfied esthetically and functionally, implant restoration was shown to be effective treatment in this case.

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Patients: The patient was a 64-year-old female with a chief complaint of strong discomfort when wearing removable dentures. She originally had bridges, but some of the abutment teeth had to be extracted, and this necessitated the change from bridges to removable dentures. To solve the problem, the patient was treated with implant-retained fixed prostheses and simultaneous treatment of residual natural teeth with new prostheses.
Discussion: Implant-retained fixed prosthesis resolved oral discomfort and achieved high patient satisfaction. Prosthetic treatment of residual teeth simultaneously with the implant restoration could realize favorable crown contours and occlusal relationship.
Conclusion: Prosthetic treatment of residual teeth simultaneously with implant restorations facilitated full-mouth reconstruction with excellent treatment outcome.

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Patient: A 73-year-old woman presented with the chief complaint of esthetic and chewing problems because of unstable dentures on both maxilla and mandibular, and right tongue sub-total extirpation. We made a treatment denture, which basically aimed at increased mouth volume and restore facial image to improve function. This resulted in improved stability of denture, oral muscles and bite.
Discussion: Using the treatment denture, the volume of the mouth was recovered and it is thought that the form harmonizes with the oral muscles and the tongue. The form is not only to be derived but also extracts the maximum function.
Conclusion: Using the treatment denture, the patient has regained oral function and progress has been satisfactory, even though, the patient has both less ridge and right tongue sub-total extirpation.

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Patients: A 65-year-old edentulous female patient visited with chief complaints of taste disturbance and pain while wearing dentures. Further investigation indicated masticatory dysfunction as a result of ill-fitting maxillary and mandibular dentures, and taste disorder was suspected to be a result of oral candidosis. After reformation of the intraoral area, new dentures were fabricated by applying the Flange technique.
Discussion: We determined that functional dentures could be produced through medication and the plaque controlled by means of instruction to the patient, who had Sjögren syndrome. Dentures were fabricated by using the Flange technique for the skin function limitation, which is a scleroderma patient’s major symptom. Thus recovery of the masticatory function became possible.
Conclusion: Maxillary and mandibular dentures were successfully produced for a systemic illness patient with functional satisfaction by applying the Flange technique.

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Patients: A 72-year-old male patient visited our hospital with a chief complaint of inadaptation and desorption of maxillary removable complete denture. Intraoral views suggested that the patient had strong bite force of grinding-type habitual mastically movement path. A fixed-implant superstructure was placed for the totally edentulous maxilla, and a metal-based denture for the mandible. During a 4-year follow-up, the prognosis has been excellent.
Discussion: Occlusal support based on the fixed-implant superstructure and the metal-base removable denture contributed to the improvement of tooth grinding and instability of the prosthesis.
Conclusion: Osseointegrated implant therapy with a fixed superstructure provided a good prognosis for a case of Eichner classification C2 with the tooth grinding habit.

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Patients: The patient was a 77-year-old edentulous male whose chief complaint was instability of his complete dentures. At his initial examination, he clearly showed mandibular prognathism and imbalanced occlusion when wearing complete dentures.
Discussion: A cephalometric analysis revealed that the position of his maxilla was found to be within normal ranges. Therefore, when new complete dentures were fabricated, landmarks on the cephalograms and upper cast were used for artificial teeth arrangement. The reconstructed occlusion improved retention and stability of the dentures. Furthermore no clinical problems or longtime observations showed the patient's satisfaction and preferable oral functions.
Conclusion: The fabrication of complete dentures made by referring to cephalograms is effective treatment for edentulous patients with obvious mandibular prognathism.

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