A pulpotomy is when the inflamed pulp chamber, usually on a baby molar, is removed, the area is sterilized, and the chamber is sealed. It is sometimes called a baby tooth root canal, but it's not really a root canal and it can be done is some cases in permanent teeth.
Princess Royal is a style customarily (but not automatically) awarded by a British monarch to his or her eldest daughter. Holders retain the style for life, so a princess cannot receive the style during the lifetime of another Princess Royal. Queen Elizabeth II never held the title as her aunt, Princess Mary, was in possession of the title. There have been seven Princesses Royal. Princess Anne is the current Princess Royal.
The Queen, The Prince and The Princess of Wales agreed that the Princess was to be known after the divorce as Diana, Princess of Wales, without the style of 'Her Royal Highness' (as The Princess was given the style 'HRH' on marriage she would therefore be expected to give it up on divorce).