Marginal adaptation of full-coverage CAD/CAM restorations: in vitro study using a non-destructive method.
OBJECTIVE
Marginal fit of full-coverage crowns is a major requirement for long term success of this kind of restorations. The purpose of the study was to verify the marginal adaptation of computer assisted design (CAD)/computer assisted manufacturing (CAM) crowns on prepared teeth and on plaster dies.


METHODS
Four couples of materials: zirconia-ceramic veneering (DC-Zircon, DCS Dental, Allschwill, CH/Cercon S, Degussa, DeguDent GmbH, Hanau, Germany), fiber-reinforced composite-composite veneering (DC-Tell, DCS Dental/Gradia, GC Europe, LEuven, Belgium), titanium-ceramic veneering (DC Titan, DCS Dental/Tikrom, Orotig, Verona, Italy) and titanium-composite veneering (DC Titan, DCS Dental/Gradia, GC Europe) were evaluated following the guidelines provided by ADA specific #8. Five crowns were fabricated for each material. Marginal gap values were measured at four points (0 degrees, 90 degrees, 180 degrees and 270 degrees starting from the centre of the vestibular surface) around the finishing line, on prepared teeth and on plaster dies at each step of the fabrication process. Digital photographs were taken at each reference point and a computer software was used to measure the amount of marginal discrepancy in microm. Statistical analysis was performed using t test at 95 percent confidence interval.


RESULTS
All the tested materials, except for fiber-reinforced composite, show a marginal adaptation within the limits of ADA specification (25-40 microm). The application of veneering material causes decay in marginal adaptation, except for fiber-reinforced composite.


CONCLUSIONS
Within the limitations of this study, it was concluded that marginal fit of CAD/CAM restoration is within the limits considered clinically acceptable by ADA specification #8. From the results of this in vitro study, it can be stated that CAD/CAM crowns produced with DCS system show a marginal adaptation within the limits of ADA specific #8, therefore milled CAD/CAM crowns can be considered a good alternative to more traditional waxing-investing-casting technique.
Romeo
E
E
Odontostomatologic Clinic, Milan, Italy. eugenio.romeo@unimi.it
Iorio
M
M
Storelli
S
S
Camandona
M
M
Abati
S
S
D002133:Calcium Sulfate; D002516:Ceramics; D003188:Composite Resins; D017076:Computer-Aided Design; D003442:Crowns / Q000592:standards; D003760:Dental Impression Materials; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008963:Molar; D011897:Random Allocation; D014025:Titanium; D015040:Zirconium
D003188:Composite Resins; C448679:DC-tell; D003760:Dental Impression Materials; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide; D002133:Calcium Sulfate