what cement do dentists use to stick crowns in and stuff?,is it as strong as cement (literally)?
First of all your friend will have to see a dentist. He's the only one to repair the tooth. You do not want to cement the composite back to the tooth, it will not stay. Any time you have composite fillings especially on front teeth you must use a fork and knife to cut your food rather than biting into something. Its very easy to replace the composite and it should be very inexpensive. Don't waste good money on trying to fix it yourself, you may do more harm than good. Please take my advice and see your dentist. Good Luck
There are many types of cement used in dentistry today. Different ones are called for different situations. Some are: Glass Ionomer, Resin Based Glass Reinforced, Polycorboxylate, Silicate and the gold standard Zinc Phosphate. There are also temporary cements as well. Every dentist has their own preference and may use 2 or 3 different types based on their likes and clinical situation. Is it as strong as cement...No! Their bond strengths are however, very strong. Usually once a crown is cemented in place, it cannot easily be removed. Often the crowns have to be cut off! They are also very water soluble, meaning that if you have a poorly made crown and saliva can leak under it, the cement may wash away and the crown will eventually fall off on its own!
Nowadays it is usually a glass ionomer cement (GIC), a resin-modified glass ionomer cement (RMGIC), or a resin cement. They are strong, adhesive, and have low solubilty (when set). Older cements such as polycarboxylate, zinc phosphate have largely gone out of fashion. Although they are very strong and very insoluble, they had a high acidity and were often associated with post-op sensitivity. They also don't work as well with the newer crown and veneer materials. Silicate cements? - not since the 70's. As strong as real cement? I don't really know how they compare, but I doubt it very much. Although strength is a factor to consider, the dental cements are only meant to be used in thin areas, so that the crown or veneer sits as closely to the tooth as possible. And as little of the cement is exposed to the salive as possible. If a crown comes off, it is not really the fault of the cement, it is usually a lack of good underlying tooth shape and size.