FDPS finish line design and tooth preparation technique.

The purpose of this research is to perform and verify the “modified 50° preparation” suggested by the authors. This procedure was performed with a scrupulous standardization of the tooth’s preparation and then of the laboratory techniques to produce a metal-ceramic crown, and the same for the crown cementation technique of on the preparation of the original sample. After the esthetic evaluations, the obtained sample was included in EPON resin and sectioned in the lingual-vestibular sense. The sections were then observed with an optical microscope in different magnifications for the final evaluations. The geometric design proposed presents the advantages of two great preparation techniques: 50° preparation and circumferential shoulder. The 50° bevel designed in first phase of preparation and the second phase of the circumferential 27° shoulder, together allowed to satisfy the following requirements: aesthetic, marginal accuracy, periodontal compliance, conservation and stability. However, this type of prosthetic preparation is not the only one, but it is one of the marginal designs in prosthetic dentistry.