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Purpose: This clinical study aimed to evaluate the outcomes of resin-bonded attachments (RBAs) for precision-retained removable dental prostheses (RDPs) after at least two years of clinical maintenance. Methods: Since December 1998, 205 RBAs (44 bonded to posterior teeth, 161 to anterior teeth) have been inserted in 123 patients (62 females and 61 males; mean age, 63.6 ± 9.6 years) who were recalled annually. The abutment teeth underwent a minimally invasive preparation limited to the enamel. RBAs were cast in a cobalt-chromium alloy with a minimum thickness of 0.5 mm and adhesively luted with a luting composite resin (Panavia 21 Ex or Panavia V5, Kuraray, Japan). We evaluated caries activity, plaque index, periodontal condition, and tooth vitality. The Kaplan-Meier survival curves were used to account for the reasons for failure. Results: The mean observation time of RBAs until the last recall visit was 84.5 ± 51.3 months (range, 3.6-270.6). During the observation period, 33 RBAs debonded in 27 patients (16.1%). The 10-year success rate according to the Kaplan-Meier analysis was 58.4%, which dropped to 46.2% after 15 years of observation if debonding was considered a failure. If rebonded RBAs were regarded as surviving, the 10- and 15-year survival rates would be 68.3% and 61%, respectively. Conclusions: The use of RBAs for precision-retained RDPs appears to be a promising alternative to conventionally retained RDPs. As reported in the literature, the survival rate and frequency of complications were comparable with those of conventional crown-retained attachments for RDPs. [ABSTRACT FROM AUTHOR]

The article focuses on a systematic review of the relationship between 8020 movement and prosthodontic treatments in Japan. Results of the study show the rapid increase of troubles after the crown and bridge placement, the possibility of crowns and bridges to extend their abutment teeth's longevity, and the capability of implants and bridges to extend the longevity of remaining teeth. As concluded, prosthodontic treatments' impacts on the 8020 movement are important and should not be neglected.

The article focuses on a study that aimed to clarify issues about clinical studies on post and core technique in Japan. The study found that the technique's failure rate reached almost two percent of all restorations and root fracture occupied 20-30% of all failures. It also discovered that single crowns have lower failure rate than abutments of fixed partial dentures.

The article presents a clinical study on the accuracy of working casts made by transfer system in Japan. A single standing ITI implant with a solid abutment was used as a master model and profile projector was being used to the dimension changes of dies measurement. The article offers conclusions including the accuracy of the stone-models and the dimension change of dies on transfer-models, the reference point's distortion on stone-models, and the distortion of the center point.

Background: The aim of this randomized controlled trial was to evaluate the capability of an IOS (Intra Oral Scanner) device, used in standardized conditions, to detect margins of abutments prepared with knife-edge finishing line located at three different levels in relation to the gingival sulcus. Methods: sixty abutment teeth for treatment with full crowns were selected and randomly divided in three groups accordingly to the depth of the finishing line: Group A: supragingival margin; Group B: 0.5–1.0 mm into the sulcus; Group C: 1.5–2.0 mm into the sulcus. Temporary crowns were placed for two weeks and then digital impressions (Aadva IOS 100, GC, Japan) were made of each abutment. As controls, analog impressions were taken, poured, and scanned using a laboratory scanner (Aadva lab scanner, GC, Japan). Two standard tessellation language (STL) files were generated for each abutment, subsequently processed, and superimposed by Exocad software (Exocad GmbH, Darmstadt, Germany), applying the "best-fit" algorithm in order to align the scan of the conventional with the digital impressions. The distances between each preparation margin and the adjacent gingival tissue were measured. Four measures were taken, two interproximally and buccally, for a total of six measures of each abutment considering three modes of impressions. The data were statistically evaluated using two-way analysis of variance (ANOVA) for each site and the Bonferroni test. Results: there was no difference between the two kinds of impression in Group A in both sites, in Group B a difference of 0.483 mm and 0.682 mm at interproximal and buccal sites, respectively, and in Group C 0.750 mm and 0.964 mm at interproximal and buccal sites, respectively. The analysis performed on a site level (mesial/distal/vestibular) for the depth of both vertical preparations revealed significant differences (p < 0.0001). After a post hoc analysis (Bonferroni), vestibular sites of the shallow vertical preparations resulted in significantly lower values compared to the other sites prepared deeply. Conclusions: the results showed that the location of the margin is an important factor in making a precise and complete impression when IOS (Intra Oral Scanner) is used. Moreover, deep preparation into the sulcus is not recommended for IOS (Intra Oral Scanner) impressions. [ABSTRACT FROM AUTHOR]

The article discusses research on the role of tooth and subject-related risk factors in the progression of periodontal disease in older people in Japan. It references a study by T. Hirotomi et al. published in the "Journal of Clinical Periodontology" in 2010. The study found an association between wearing a removable partial denture (RPD) and progression of periodontal disease over five years. Multirooted teeth and abutments for RPDs and fixed partial dentures (FPDs) were determined as possible risk factors for disease progression.

This study aimed to examine the influence of osseointegrated implants on decision making for prosthodontic treatments. Twenty-five randomly selected Japanese dental clinicians in 1995 and 2005 with 5 to 15 years of clinical experience were requested to define bone support levels for prosthodontic treatment options. Comparison of the results expressed with the fuzzy function between 1995 and 2000 showed that indications for extraction have expanded with the prevalence of osseointegration concepts. Further, the definition of poor bone quality has changed. Osseointegration has influenced the decision-making process in prosthodontic treatments related to extraction.