Even after 50 years of regular service, PFM restorations still have room for improvement. To produce optimum PFM restorations, it is necessary for the dentist and dental laboratory to work together closely to ensure they communicate both impression and shade information accurately. PFM tooth preparations require approximately 1.2–1.5 mm of reduction on all surfaces except for the occlusal, which requires 2.0 mm of reduction. Strategically placed cuts at these specific depths are quite beneficial in ensuring proper reduction has been accomplished. Without proper reduction, the longevity and overall esthetics of the PFM restoration will be negatively affected. PFM impressions need to be as accurate as possible. A national laboratory association reports that 90 percent of impressions for full crowns do not include all tooth preparation margins around the entire periphery of the tooth. Modern ceramics have excellent strength and esthetic characteristics when they are fired no more than 1.5–2 mm thick (porcelain will likely fracture when fired thicker than 2.0 mm). Resin reinforced glass ionomers are the most popular cements used today because they are easy to use, strong, relatively insoluble, fluoride releasing and bond to tooth structure.