Statement Of Problem: Clinical studies have shown that lack of retention is one of the major causes of fixed dental prosthesis failure.
Purpose: The purpose of this study was to determine the relationship between the convergence angle of a complete metal crown tooth preparation and the recementation strength for restorations cemented with conventional and adhesive cements.
Material And Methods: One hundred twenty artificial crowns were cast for standardized complete metal crown tooth preparations accomplished with the use of a milling machine on extracted human teeth. Three different tapers, 5, 12, and 25 degrees, were used (n=40). The crowns in each group were subdivided into 4 subgroups (n=10) according to the luting cement: zinc phosphate cement (Fleck's), glass ionomer cement (Ketac-Cem), and adhesive resin cements (Panavia 21 and C&B-Metabond). Retention was evaluated by measuring the tensile force required to dislodge the crowns from the tooth preparations in a universal testing machine. Subsequently, the tooth preparations were scraped clean and polished with prophylaxis paste, and the intaglio surfaces of the artificial crowns were ultrasonically cleaned and airborne-particle abraded with 50-mum aluminum oxide powder prior to recementation. The data were analyzed with 3-way repeated-measures ANOVA and Tukey's HSD test (alpha=.05).
Results: Analysis of measurements disclosed a significant difference for taper and luting cement (P<.001); however, their interaction was not significant. Also, there was a statistically significant difference between the retention of the first cementation and the second cementation (P<.001). However, the interaction was not significant with taper or cement. Regardless of the taper used, Panavia 21 cement exhibited the highest mean initial retention, but the difference was not significantly different from the recementation retentive strength.
Conclusions: Tooth preparation taper and type of luting cement had a direct effect on the recementation strength of complete metal crowns.
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http://dx.doi.org/10.1016/S0022-3913(09)60192-X | DOI Listing |
Environ Sci Pollut Res Int
January 2025
Occupational Environment Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran.
Sodium chloride, commonly referred to as table salt, is the most widely utilized seasoning in culinary applications. Nevertheless, the most of oral salts used contain impurities. Arsenic (As), mercury (Hg), cadmium (Cd), and lead (Pb) are the most common impurities found in salt.
View Article and Find Full Text PDFTrop Anim Health Prod
January 2025
Department of Agroindustrial Science and Technology, Federal University of Pelotas, Rio Grande Do Sul, Brazil.
During the harvest of Ilex paraguariensis, approximately 2-5 tons per hectare of thick stems are left on the soil surface. The outer portion of these stems, referred to as the coproduct, constitutes 30% of the total residue mass. Although this coproduct has been partially characterized in terms of its phytochemical profile, its technological applications remain unexplored.
View Article and Find Full Text PDFAcc Chem Res
January 2025
The Wolfson Catalysis Centre, Department of Chemistry, University of Oxford, Oxford OX1 3QR, U.K.
ConspectusThe discovery of reversible hydrogenation using metal-free phosphoborate species in 2006 marked the official advent of frustrated Lewis pair (FLP) chemistry. This breakthrough revolutionized homogeneous catalysis approaches and paved the way for innovative catalytic strategies. The unique reactivity of FLPs is attributed to the Lewis base (LB) and Lewis acid (LA) sites either in spatial separation or in equilibrium, which actively react with molecules.
View Article and Find Full Text PDFJ Environ Sci Health B
January 2025
Faculty of Food Technology, University of Economics-Technology for Industries (UNETI), Hanoi, Vietnam.
Antibiotic residues have become serious health concerns due to the development of antibiotic-resistant bacteria. The treatment of antibiotic pollutants in wastewater is necessary for reducing the issue of antibiotic resistance. In this work, the metal oxide photocatalyst titanium dioxide (TiO) was evaluated for the removal of the tetracycline antibiotic (TC-A) and the deactivation of bacteria (E-B) from wastewater.
View Article and Find Full Text PDFFront Oral Health
January 2025
State Key Laboratory of Oral & Maxillofacial Reconstruction and Regeneration, National Clinical Research Center for Oral Diseases, Shaanxi Clinical Research Center for Oral Diseases, Department of Pediatric Dentistry, School of Stomatology, The Fourth Military Medical University, Xi'an, China.
Objective: To analyze the clinical application and limiting factors of the Hall technique (HT) preformed metal crowns in caries of primary molars and to provide reference for its clinical application based on a questionnaire survey.
Materials And Methods: From June to December 2022, a questionnaire was distributed to pediatric dentists through the WeChat platform using "Questionnaire Star" to analyze the clinical application and influencing factors of the HT preformed metal crowns in caries of primary molars.
Results: A total of 700 survey questionnaires were distributed, and 650 valid questionnaires were recovered, with a effectiveness rate of 92.
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