THE secret to Kate Middletons perfect smile is out and its all to do with its gleaming imperfection. Her pearly whites have long been the talk of the US and Canada but no-one knew exactly how the Duchess of Cambridge perfected her stunning smile. It has now been revealed Kate picked a French dentistry expert whose speciality is creating an imperfect look to mould her mouth into shape. Didier Fillion is a pioneering dentist based in Wimpole Street who doesnt just whiten and straighten teeth but does what he calls 'micro-rotations. And according to Dr Fillions friend and fellow dentist, Bernard Touati, it is this imperfection which makes Kates smile so endearing. He told The Times: 'You know why they look so good? Because they are not absolutely aligned. 'The problem in the United States is they have a very artificial vision. He did some little micro-rotations on Kate Middleton [to produce] something which is natural. That is what we like; a natural healthy smile, but not artificial. Dr Fillions speciality is that he attaches invisible braces to the backs of teeth. But the dentist said micro-rotation can be achieved quickly by grinding and polishing existing tooth enamel or by adding porcelain veneers. Dr Fillion said creating the perfect smile can take from six months to two years and will set you back between 4,000 and 11,000. Other patients of the French dentist include Kelly Brook and Sadie Frost who are believed to have used the invisible brace micro rotation treatment. The dentist, who refuses to confirm or deny the Duchess was a patient, said he offers something other dentists dont usually, a service which allows patients to see exactly what their teeth will look like when treatment is over. On his website the dentist says he is known for his expertise and the environment he creates for his treatment. He said: 'We have the software so if you say, I dont like this tooth, can you change it?, I can change it. He writes:I consider every single patient as a unique individual with a past history, with concerns, and also with dreams. It is important for me to understand what the patient wishes to achieve through his orthodontic treatment. 'Thus, I try to create a pleasant environment, a comfortable and welcoming atmosphere in order to start a good relationship and make a total success out of the patients orthodontic experience. MOL 'A treatment is fully accomplished only when the patient himself is totally satisfied with the final result : when his smile has become the smile of his dreams MOL