DENTAL Preparation Assisted by Guides volume 1 crown preparation on anterior toothPAG or Preparations Assisted by Guides are based on the combined use of special burs. The protocols that drive them are established from the principle according to which the burs are not simply intended to wear away the tooth by abrasion but they are each at their level, real tools whose function is to satisfy the criteria necessary to produce our fixed prostheses. PAG made Cerec and cadcam dentistry easy.