Preliminary evaluation of tin plating for extracoronal restorations: evaluation of marginal quality and retention.
OBJECTIVE
The influence of tin plating on marginal seating and retention of complete cast crowns was evaluated.


METHODS
Thirty-six standardized gold-alloy complete crowns were made on extracted human molar teeth prepared with a modified milling machine using conventional laboratory techniques. The crowns were randomly assigned to two groups according to the treatment of the fitting surface (air abraded with 50-micron aluminum oxide for 10 seconds, or tin plated with a microtin system for 3 seconds), and luted with adhesive resin cement (Panavia-EX, J. Morita). Scanning electron microscopy was used to evaluate the variables for the cast alloy. Retention was measured with an instron testing machine after thermocycling (1,500 cycles between 5 degrees C and 55 degrees C with 1 minute dwell times). Marginal adaptation was measured with a Nikon microscope before and after cementation. Results were subjected to one-way analysis of variance and Student's t test.


RESULTS
Retention was significantly different (P < 0.001); the highest retention (367 N) was reported in tin-plated crowns. Differences for marginal seating were not statistically significant.


CONCLUSIONS
Tin plating after air abrasion was found to be a predictable and simple technique to roughen the casting surface, increase the surface area for bonding, and significantly improve the retention of cast crowns in vivo.
Ayad
M F
MF
Section of Restorative Dentistry, Prosthodontics, and Endodontics, University of Tanta College of Dentistry, Egypt.
Rosenstiel
S F
SF
D000704:Analysis of Variance; D003442:Crowns; D003735:Dental Casting Technique; D018772:Dental Marginal Adaptation; D017268:Dental Prosthesis Retention / Q000379:methods*; D004595:Electroplating; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D008422:Materials Testing / Q000379:methods; D008855:Microscopy, Electron, Scanning; D008963:Molar; D013499:Surface Properties; D014001:Tin / Q000737:chemistry*
D006047:Gold Alloys; D014001:Tin