Wear of enamel and veneering ceramics after laboratory and chairside finishing procedures.
OBJECTIVE
This in vitro study compared the wear of enamel against 3 types of ceramics with high esthetic potential (designed for layering techniques): feldspathic porcelain (Creation), aluminous porcelain (Vitadur alpha), and low-fusing glass (Duceram-LFC). Laboratory finishing (glazing/polishing) and chairside polishing with a Dialite kit were simulated to compare their respective effects on wear.


METHODS
Tooth-material specimen pairs were placed in an artificial mouth using closed-loop servohydraulics. Constant masticatory parameters (13.5 N occlusal force, 0.62 mm lateral excursion; 0.23 second cuspal contact time) were maintained for 300, 000 cycles at a rate of 4 Hz. The occlusal surface of each pair was mapped and digitally recorded before and after each masticatory test. Quantitative changes were measured in terms of depth and volume of wear. Quantitative wear characteristics were assessed by SEM.


RESULTS
Significant differences were observed (2-factor ANOVA, P <.05). Duceram-LFC generated increased volume loss of enamel (0.197 mm(3)) compared with Creation (0.135 mm(3)) and Vitadur alpha (0.153 mm(3)). Creation exhibited the lowest ceramic wear and lowest combined volume loss (0.260 mm(3); the sum of the data for enamel and the opposing material) compared with Duceram-LFC (0.363 mm(3)) and Vitadur alpha (0.333 mm(3)). The most significant differences among materials were observed in volume loss, not in depth of wear. For all 3 ceramic systems, qualitative SEM evaluation revealed an abrasive type of wear. Wear characteristics of chairside polished specimens were similar to those of laboratory finished specimens (glazed and polished).


CONCLUSIONS
Duceram-LFC was the most abrasive ceramic for the antagonistic tooth. Creation ceramic was the least abrasive material and most resistant to wear. Defects, brittleness, and the possibly insufficient toughness of LFC may explain its increased abrasiveness. Laboratory and chairside finishing procedures generated similar results.
Magne
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School of Dentistry, University of Minnesota, Minneapolis, MN, USA. Pascal.Magne@medecine.unige.ch
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Pintado
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DeLong
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D000704:Analysis of Variance; D001732:Bite Force; D003743:Dental Enamel / Q000648:ultrastructure; D003775:Dental Polishing; D003776:Dental Porcelain / Q000009:adverse effects / Q000737:chemistry; D019554:Dental Restoration Wear; D003801:Dental Veneers / Q000009:adverse effects; D006244:Hardness; D008409:Mastication; D008422:Materials Testing; D008689:Methacrylates; D008855:Microscopy, Electron, Scanning; D009943:Organophosphorus Compounds; D019217:Tooth Attrition / Q000209:etiology*
C095718:Duceram; D008689:Methacrylates; D009943:Organophosphorus Compounds; C111324:vitadur alpha omega; C056665:creation bond; D003776:Dental Porcelain