D. Decurcio, J. A. Silvaa, Mateus Gehrke Barbosa, L. S. Chaves, M. Loureiro, C. Estrela
{"title":"Characterization of the nucleus, cutting edge and failure detection in NiTi instruments for endodontic retreatment","authors":"D. Decurcio, J. A. Silvaa, Mateus Gehrke Barbosa, L. S. Chaves, M. Loureiro, C. Estrela","doi":"10.15448/1980-6523.2017.4.30157","DOIUrl":"https://doi.org/10.15448/1980-6523.2017.4.30157","url":null,"abstract":"OBJECTIVE: To characterize the nucleus, cutting edge and to detect defects in surfaces of nickeltitanium (NiTi) instruments for endodontic retreatment.METHODS: The selected endodontic instruments (D-RaCe, ProTaper retreatment and Mtwo retreatment) were evaluated prior to their use in 30- and 50-fold magnification in scanning electron microscopy (SEM), for linear measurements of lateral cut edge areas and of the nucleus and the ratio between these measures. After use in simulated canals, faults in the active surface were analyzed by SEM with 30 and 50 times magnification, and 200 times magnification when faults were found. The images were examined by three evaluators, whose measurements were previously calibrated. The defects analyzed were crack, blunt and barb, and data were tabulated for analysis.RESULTS: The instruments studied differed in results. The D-RaCe system instruments had the highest nucleus:edge ratio, while ProTaper retreatment instruments yielded the lowest ratio. All instruments presented some defect, with the instruments Mtwo retreatment presenting two instruments with defects.CONCLUSION: All analyzed instruments presented some type of failure after using them for removal of the filling material of simulated root canals. The D-RaCe system presented the highest edge measurements and the smallest nucleus measurements, contrary to the ProTaper retreatment system, which presented the smallest edge measurements and the largest core measurements.","PeriodicalId":38878,"journal":{"name":"Revista Odonto Ciencia","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15448/1980-6523.2017.4.30157","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42152099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Josué Ricardo Broilo, E. A. Sartori, Luiz Oscar Honorato Mariano, L. Corso, R. Shinkai
{"title":"Three-dimensional finite element analysis of mandibular overdentures with different implant positions and attachment types","authors":"Josué Ricardo Broilo, E. A. Sartori, Luiz Oscar Honorato Mariano, L. Corso, R. Shinkai","doi":"10.15448/1980-6523.2017.4.28877","DOIUrl":"https://doi.org/10.15448/1980-6523.2017.4.28877","url":null,"abstract":"OBJECTIVE: This 3-D FEA study compared the stress distribution in two-implant mandibular overdentures as a function of implant position and attachment system (LA: locator attachment vs. BA: ball attachment).METHODS: Four models of mandibular overdentures were tested: M1-LA – with implants at the canine regions (standard implant position) and LA; M2-LA – with implants placed at the first premolar regions (distalized implant position) and LA; M1-BA – with standard implant position and BA; and M2-BA – with distalized implant position and BA. The geometric models were converted into finite element models. A 100 N axial load was applied at the first molar region. The von-Mises stress distribution was compared in selected points.RESULTS: The models with BA had pattern of stress distribution was more uniform along the implant axis than the ones with LA, although the stress magnitude was larger. The largest area of von Mises stresses on the alveolar ridge was in the models with standard implant distribution.CONCLUSION: The findings showed that the models with BA had better biomechanical behavior than the ones with LA. For both types of attachment, the models with increased inter-implant distance presented a smaller area of stress distribution in the perimplant cortical bone tissue than the standard implant position. ","PeriodicalId":38878,"journal":{"name":"Revista Odonto Ciencia","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15448/1980-6523.2017.4.28877","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41635492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luisa Drummond, R. M. H. Segundo, H. M. Oshima, R. Shinkai
{"title":"The effect of surface texture on the retention of single implant-supported crowns cemented on wide-platform abutments","authors":"Luisa Drummond, R. M. H. Segundo, H. M. Oshima, R. Shinkai","doi":"10.15448/1980-6523.2017.4.28739","DOIUrl":"https://doi.org/10.15448/1980-6523.2017.4.28739","url":null,"abstract":"OBJECTIVE: This in vitro study evaluated the retention of copings cemented with a provisional cement and a permanent cement on wide-platform short abutments with different surface texture.METHODS: Two wide-platform abutments (height 4.0 mm) with machined (original) or modified surface (air-blasted with 50-µm aluminum oxide) were connected to two implant replicas under torque of 35 N.cm. Ten copings were cast in Cr-Co alloy from calcinable cylinders. Each coping was luted on the abutment under an axial force of 5 kg for 10 min, and the specimen was stored in a humid environment at 37°C for 20 h. After mechanical cycling simulating masticatory fatigue for 7 days (5754 cycles, 60 cycles/min, 200 N, 37°C), the specimens were subjected to a uniaxial tensile test at 0.5 cm/min, and the maximum retention strength (N) was recorded. After testing, the surfaces were cleaned, and the procedures were repeated for each coping in the experimental group. Data were analyzed by Student t test for paired samples. RESULTS: For the temporary cement, the mean retention (SD) was 36.1 (10.7) N for the machined surface and 49.6 (2.7) N for the blasted surface (P=0.004) (37% increase). For the zinc phosphate cement, the values were 292.0 (89.8) N and 440.6 (48.1) N, (P<0.001) (42% increase).CONCLUSION: The results suggest that the air-blasting of short and wide abutments increases the retention of the cast coping cemented with temporary or permanent cement.","PeriodicalId":38878,"journal":{"name":"Revista Odonto Ciencia","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.15448/1980-6523.2017.4.28739","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46734149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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