It is possible to replace the lost cap as nothing much has to be done. The dentist will just take the impressions and get the crown prepared .When it comes from the lab the dentist will fix it. It is a safe procedure and can be done easily. Rather i suggest you should get it done  as with out cap the tooth can get infected and you can land up in trouble.For more info on dental crown you can visit the following link on our website.......http://www.identalhub.com/articlecategory-dental-crowns-72.aspx