A recent study found that ceramic crowns made by CAD/CAM held up just as well as gold crowns after a year in patients' mouths. But now an article in Evidence-Based Dentistry argues out that it's too early to draw conclusions.
For the original study, published in the Journal of Oral Rehabilitation (March 2009, Vol. 36:3, pp. 226-235), researchers at the University of Freiburg and University Hospital, Hamburg-Eppendorf, randomly divided 224 patients into two groups.
They placed KaVo Everest high-performance ceramic crowns in 123 patients using a KaVo CAD/CAM system and gold conventional crowns in 101 patients. After six months and again after a year, they examined all the crowns for loss of vitality, surface roughness, fractures, marginal integrity, secondary caries at the crown margin, margin discoloration, marginal gap, and crown loss.
They found no statistically significant differences between the two groups, except that no perfect marginal fit was shown by 49.5% of the evaluated ceramic crowns and 26.1% of the gold crowns.
But it's too early to conclude that CAD/CAM crowns are as good as gold, argues Elliot Abt, D.D.S., of the Illinois Masonic Medical Center, in the article in Evidence-Based Dentistry (2010, Vol. 11:1, pp. 25-26). "The most glaring weakness with this study is that only a 12-month observation period was completed at publication," he wrote. "Extrapolating to one's clinical practice is difficult here, as prosthesis survival studies typically run from five to 20 years to allow for failures to occur."
Dr. Abt noted that the researchers plan to continue publishing longer-term results.
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