Influence of recasting on the quality of dental alloys: A systematic review.
BACKGROUND
Dental alloy manufacturers advise against the reuse of previously melted alloy. However, for economic reasons, dental laboratories often reuse the casting surplus (sprue and metal remaining in the crucible former). Such reuse remains a controversial topic in dental practice.


OBJECTIVE
The purpose of this systematic review was to assess the effects of remelting dental alloys by evaluating the following parameters: reasons for recasting and associated processes, feasible number of recastings, treatment of alloys before recasting and its effects on cytotoxicity, color of opaque porcelain, castability of alloys, marginal accuracy, mechanical properties, porcelain-metal interfaces, and corrosion.


METHODS
The systematic review included all studies on dental alloy recasting. MEDLINE, Dentistry and Oral Science Source, Science Direct, and ISI Web of Science were searched (up to July 2014). Data were extracted and the quality of studies was assessed.


RESULTS
Thirty-four studies published between 1983 and 2014 were included. The number of recastings ranged from 1 to 10. The percentage of new alloy ranged from 0 to 100 wt%, although the mean value was 50 wt%.


CONCLUSIONS
Evidence for the feasibility of adding 50% new metal at each recasting is limited. The number of recastings should be limited to a maximum of 4. No general test protocol can be deduced from these studies, which limits the comparison and exploitation of data. Furthermore, no consensus protocol exists for the evaluation of recasting. Future studies should work toward establishing a standard protocol.
Graduate student, Department of Prosthodontics, University of Lorraine, Nancy School of Dentistry, Nancy Cedex, France.
Anne-Sophie
AS
Vaillant-Corroy
Graduate student, Department of Prosthodontics, University of Lorraine, Nancy School of Dentistry, Nancy Cedex, France.
Pascale
P
Corne
Associate Professor, Department of Prosthodontics, University of Lorraine, Nancy School of Dentistry, Nancy Cedex, France.
Pascal
P
De March
Associate Professor, Research group DOLPHIN, Nanomaterials to Life, Department N2EV, Institut Jean Lamour, Nancy Cedex, France.
Solenne
S
Fleutot
Associate Professor, Research group DOLPHIN, Nanomaterials to Life, Department N2EV, Institut Jean Lamour, Nancy Cedex, France. Electronic address: franck.cleymand@univ-lorraine.fr.
Franck
F
Cleymand
D003116:Color; D003343:Corrosion; D003722:Dental Alloys / Q000592:standards* / Q000633:toxicity; D003735:Dental Casting Technique / Q000592:standards; D003776:Dental Porcelain / Q000592:standards; D017743:Equipment Reuse / Q000592:standards*; D006801:Humans; D008422:Materials Testing; D055595:Mechanical Phenomena; D016876:Metal Ceramic Alloys / Q000592:standards; D013499:Surface Properties
D003722:Dental Alloys; D016876:Metal Ceramic Alloys; D003776:Dental Porcelain