Sure, a dental crown might need to be replaced after it's been in place for a number of years. While the crown itself may change, the method acts as a permanent restoration for a permanent tooth. It's not as though this type of restoration has any benefit for a deciduous, baby tooth, does it?
Temporary, But Essential
Baby teeth are temporary, but they're still essential for a considerable period of time, and the wellbeing of baby teeth can have a direct impact on the development of adult teeth. This is why when a baby tooth has succumbed to decay or has been damaged in an accident, a dental crown can be fitted by a children's dentist.
The Tooth's Structure
A crown on a baby tooth becomes part of the tooth's structure (which is largely the point of a crown), and will not interfere with the development of your child's permanent teeth. The baby tooth (crown and all) will still have its root structure dissolved by the adult tooth developing underneath it, and one of the teeth under your child's pillow (awaiting a visit from the Tooth Fairy) will simply have a crown attached to it. However, because the crown is intended to be lost, its material can differ from a crown for a permanent, adult tooth.
The esthetics of the crown will play a major role in determining the best material. When the tooth requiring a crown is a rear molar, your child's dentist will likely opt for a stainless steel crown. This is durable and can handle the bite pressure that molars are subjected to. Stainless steel crowns are easy to apply, which is beneficial for younger patients.
The Smile Zone
A stainless steel crown has a tendency to look like a gigantic, old-fashioned metal dental filling, which is why they're typically reserved for rear teeth, where they won't be all that conspicuous. Front teeth, especially those in the smile zone, are another matter. Yes, your child can receive a porcelain crown (much like an adult tooth), although the expense of this type of restoration means that it's not always the best financial choice.
Your child's dentist might recommend a resin or polycarbonate crown, which are both made of durable plastic, colour-matched to your child's other teeth. They don't have the longevity of a porcelain crown, but this is largely irrelevant since they only need to last for a few years or so.
Sometimes a child will need a dental crown, but this will rarely be the same as an adult crown. To learn more, contact a children's dentist.