Clinical use of duplicate complete dentures: A narrative review.

Most reports on duplicate dentures are introduction to fabrication methods or clinical case reports. Only a few studies have verified their clinical effectiveness; hence, evidence to construct useful clinical guidelines for duplicate denture use is lacking. This review aimed to comprehensively investigate reports on duplicate dentures to accumulate evidences that will contribute to the formulation of clinical practice guidelines. Duplicate dentures are effectively used for impression making and bite registration when fabricating new dentures, thereby reducing the number of clinic visits and treatment time. Duplicate denture can also be used as temporary or new dentures. Older people in whom various adaptive abilities have declined, may find it difficult to adjust to new dentures and experience stress, even if the shape is appropriate. Duplicate dentures, which reproduces the shape of old dentures that they are used to, have the advantage of being more familiar to older people and less stressful. When manufacturing duplicate dentures, digital methods such as milling and three-dimensional printing are superior to conventional methods regarding working time and cost. A notable advantage of the digital method is that the denture shape can be saved as digital data, and the denture can be easily duplicated if lost.

Application of one-piece endodontic crowns fabricated with CAD-CAM system to molars.

Computer-aided design-computer-aided manufacturing (CAD-CAM) systems have been widely used as a fabrication method for restorations because of their high efficiency and accuracy, which significantly reduces fabrication time. However, molars with insufficient clearance or short clinical crown lengths require retention holes or grooves on the preparation, making it difficult to replicate the shapes with the CAM milling system. In these cases, restorations using the lost-wax method are selected. This article focuses on one-piece endodontic crowns (endocrowns) fabricated with a CAD-CAM system (CAD-CAM endocrowns), in which their posts and crowns are integrated. Articles from July 2012 to August 2023 were searched in PubMed with the keyword "endocrown". This review discusses the application of CAD-CAM endocrowns to molars from the viewpoint of model experiment (fracture resistance, adaptation) and clinical research. This technique, which allows margins and internal gaps to be set within the clinically acceptable range, is reported to be an effective way of restoring molars with high survival rates in clinical research.

Effectiveness of denture space recording method in the prosthetic treatment of edentulous patients.

PURPOSE: To present a clinical rationale for the effectiveness of denture space recording methods for the prosthetic treatment of edentulous patients through a review of the literature. STUDY SELECTION: A total of 3167 studies were extracted from a search of four terms, namely denture space, neutral zone technique, flange technique, and piezography using PubMed and J-STAGE databases. A total of 57 documents that matched the inclusion and exclusion criteria were selected. RESULTS: From the extracted articles, the clinical application of denture space recording methods was found to be effective in edentulous patients with severe ridge resorption. The relationship between the labiolingual and buccolingual pressure in patients with neuromuscular problems or with mandibular or lingual defects differs from those without it, so a stable prosthesis can be easily fabricated by locating the neutral zone using denture space recording methods. CONCLUSION: The literature on denture space recording methods suggests that its application on challenging cases of edentulous patients is useful in providing prostheses with improved retention and stability.

Current complications and issues of implant superstructure.

The purpose of this review is to search for complications of dental implant superstructures and consider the issues involved. This narrative review was performed by searching through PubMed databases and review articles that were published after 1990. Misfitting of the superstructure can result in loosening of screws, reduced preload, and in some cases, significant stress around the implant. External connection modalities and single implant prostheses have been reported to have more loose or broken abutment screws. In addition, when zirconia abutment was used for platform shifting, the rate of fracture of the abutment was considered to be high. Additionally, it was reported that men were significantly at an increased risk of abutment fracture. As for the retention mechanism of implant overdenture, stud attachment (Locator type) should receive more attention to wear and damage of retention parts than other attachments. The causes of the complications of implant superstructures have not been clarified in some cases, and further verification is required. Verification of complications is considered important to obtain a long-term prognosis for superstructures of implants. It will be necessary to further verify complications of implants in the future.

Longevity of resin-bonded fixed partial dentures made of metal alloys: A review of the literature.

Purpose In this review, we evaluate the survival rate of resin-bonded fixed partial dentures (RBFPDs) made of metal alloys.Methods An electronic search of English peer-reviewed dental literature on PubMed was conducted to identify all publications reporting on RBFPDs made of metal alloys until March 2019. The searched keywords were: bridge OR fixed partial denture OR fixed prosthesis OR fixed prostheses AND resin bonded AND metal OR alloy AND survival OR longevity (RBFPD was not included). Furthermore, the "Related Articles" feature of PubMed was used to identify further references of interest during the primary search. A definitive list of articles was screened to extract qualitative data after the application of the inclusion and exclusion criteria, and the results were analyzed.Results Overall, 977 publications were found through an electronic and manual search, out of which 130 articles were selected after screening based on title and abstract. A total of 52 publications passed the second review phase after assessment for eligibility, from which 24 studies were excluded after full-text screening. Finally, a total of 28 studies were selected.Conclusions The survival rate of RBFPDs differed greatly depending on the type of metal alloy, adhesion system, and observation period assessed, e.g. the 10-year survival rate ranged from 18% to 88%. The wide range of survival rates of the RBFPDs reported indicates that though RBFPD is a reliable prosthesis, it is prone to failure if some processes are not completed.

Direct bonded fixed partial denture with an artificial denture tooth as a pontic.

Background: The present review aimed to investigate the feasibility and clinical effectiveness of a direct bonded fixed partial denture (DBFPD) based on available literature. The efficiency of a DBFPD is mainly affected by the type of artificial denture tooth, the type of luting agent, and the adhesive preparation. Methods: The parameters were reviewed based on the in vitro and in vivo studies conducted. An acrylic resin tooth or a composite resin tooth for removable dentures should be used as the artificial tooth for the pontic. Results: Considering the luting agent, a methyl methacrylate-based resin luting agent, which has low mechanical strength but is capable of plastic deformation and could sustain for a long time, should be used. Appropriate pre-adhesive treatment should be performed on both the artificial and abutment teeth. The cases in which a DBFPD can be applied are limited to one missing anterior tooth, as long as it is not overstressed. Patient cooperation in cases of occlusion seems to be another prerequisite. Conclusion: Knowledge and selection of the material and case indications are essential, and patient cooperation is pertinent in studying the long-term prognosis of a DBFPD.

Reliability and validity of the patient disability-oriented diagnostic nomenclature system for prosthetic dentistry.

PURPOSE: The Japan Prosthodontic Society (JPS) has proposed a new diagnostic nomenclature system (DNS), based on pathogenesis and etiology, to facilitate and improve prosthodontic treatment. This system specifies patient disability and the causative factor (i.e. "B (disability) caused by A (causative factor)"). The purpose of this study was to examine the reliability and validity of this DNS. STUDY SELECTION: The JPS Clinical Guideline Committee assessed mock patient charts and formulated disease names using the new DNS. Fifty validators, comprising prosthodontic specialists and dental residents, made diagnoses using the same patient charts. Reliability was evaluated as the consistency of the disease names among the validators, and validity was evaluated using the concordance rate of the disease names with the reference disease names. RESULTS: Krippendorff's α was 0.378 among all validators, 0.370 among prosthodontic specialists, and 0.401 among dental hospital residents. Krippendorff's α for 10 validators (3 specialists and 7 residents) with higher concordance rates was 0.524. Two validators (1 specialist and 1 resident) with the highest concordance rates had a Krippendorff's α of 0.648. Common disease names had higher concordance rates, while uncommon disease names showed lower concordance rates. These rates did not show correlation with clinical experience of the validator or time taken to devise the disease name. CONCLUSIONS: High reliability was not found among all validators; however, validators with higher concordance rates showed better reliability. Furthermore, common disease names had higher concordance rates. These findings indicate that the new DNS for prosthodontic dentistry exhibits clinically acceptable reliability and validity.

[Barrel finishing of cobalt-chromium alloy cast plate--basic study on polishing materials and time].

PURPOSE: This study was designed to establish the optimum grinding condition of barrel finishing for cobalt-chromium alloy. Smoothing of the mucosal surface, reduction of labor, and improvement of the working environment were estimated by the application of barrel finishing to cobalt-chromium alloy. METHODS: Tabular test pieces cast in cobalt-chromium alloy whose surface was standardized by waterproof abrasive papers were used in this study with a centrifugal flow barrel finishing machine. The abrasive that was most suitable for the primary polishing was selected, and proper polishing time was then decided by measuring the surface roughness of the test pieces. The abrasive and polishing time for the secondary polishing were decided in the same manner. Finally, the surface texture of the test pieces, which were finished in this condition by the manufacturer's instruction or by the electrolytic polishing method, were compared. Statistic analysis was performed by one-way analysis of variance and the multiple comparison test. RESULTS: A triangular prism-shape abrasive made of Al(2)O(3) and SiO(2) whose one side or height was 6 mm was selected for the primary polishing, and the same kind of abrasive with one side or height of 4 mm was chosen for the secondary one. The optimum polishing time for the primary polishing and the secondary polishing were 60 minutes and 40 minutes, respectively. The surface roughness of the test pieces that were finished in this condition was significantly smaller than that finished following the manufacturer's indication or that finished by the electrolytic polishing method. CONCLUSION: The optimum polishing condition of barrel finishing for cobalt-chromium alloy was established in this study. For the polished surface of cast dentures, polishing by a rotary cutting instrument after barrel finishing in this condition would be needed, as no luster was observed on the finished surface.