The term "crown" is used to describe the portion of your tooth that extends above the gumline - in other words, the portion of the tooth that can be seen in a healthy mouth. It is also used more colloquially to describe the dental procedure of having a prosthetic "crown" placed over a decayed, chipped, cracked, or otherwise damaged tooth.
With this dental procedure code the prosthetic crown fitted over the tooth is made predominately of base metal, and then covered, at least partially, with a tooth-colored synthetic resin to enhance its cosmetic appeal. Synthetic resins are liquid materials that can be converted into a permanent hardened material, and in dentistry are most commonly acrylic polymer or polymethyl methacrylate. A crown comprised of mainly base metal, is designated as such because less than 25% of its composition is of the noble metals gold, platinum, palladium, and silver. Noble metals are known to interact with human tissue well, and hold up to corrosion and oxidation better than other metals. The higher the percentage of noble metals, the less likely a crown is to corrode or oxidize, as is the case with crown procedures (Resin With High Noble Metal) and (Resin With Noble Metal), which contain a higher amount of noble metals.
Use of the two materials together, is done when extensive repair is needed within the "smile zone," and a full gold crown - despite its greater longevity and strength - is not preferred for cosmetic reasons. With this procedure, because the metal strengthening core is covered with a tooth-colored resin, you can achieve excellent cosmetic results, in addition to the durability that stems from the underlying metals.
To prepare for this type of crown, a dentist will first remove any decayed or weakened areas of the tooth, and reduce its overall shape to accommodate the crown. A mold of your bite will then be made, so the custom crown can be fabricated off-site at a dental lab. If desired, a temporary crown can be fitted until the custom crown is completed.