Review Article DOI: 10.18231/2455-8486.2016.0003 Annals of Prosthodontics & Restorative Dentistry, October-December 2016:2(4):110-114 110 The Today & Tomorrow of fixed Prosthodontics Sonia Nanda 1,* , Tarun Nanda 2 , Deepak Grover 3 1 Reader, Dept. of Prosthodontics & Crown & Bridge, 3 Reader, National Dental College, Punjab, 2 Reader, Dept. of Periodontics, Bhojia Dental College, Baddi, Himachal Pradesh *Corresponding Author: Email: drsonia84@gmail.com Abstract The scientific and technological basis of dentistry, are expanding rapidly in a world where alternative changes in the managements and financing of health care and public expectations of better “quality of life” are there. In this paper, many significant changes taking place in fixed prosthodontics are discussed and suggestions regarding the importance and potential influence of the changes are made. Keywords: Impressions, All-ceramic, Provisional restorations, Tooth preparation Introduction Large numbers of crowns and fixed prostheses are accomplished daily. Most general practitioners would agree that this area of dentistry is the largest single income producer in their practices and that increasing numbers of patients need this treatment or demand it for reasons of esthetics. During the last 40 years, there is significant increase in the quantity of fixed prosthodontics. Materials and techniques have improved. Some of these changes are well-proven, while others are in process of being accepted or rejected. More changes are occurring in fixed prosthodontics than in almost any other area of dentistry. Electric handpieces versus air-driven handpieces Electric handpieces have been the most popular tooth-cutting mechanism in numerous countries for years. But in some areas, clinician’s use of electric handpieces is just beginning to mature where air-rotars and air-motors long have been the dominant instruments for cutting tooth preparations. (1) Electric handpieces are quiet during use, they posses high torque, even at low speed and they are concentric if they are maintained well. The disadvantages are equally evident after minimal use. Electric handpieces have larger heads than air-driven handpieces; they heat up if not maintained well; and if soft tissue or intraoral objects such as cotton rolls, in the path of the rotating instrument make contact with the bur, the result is a significant challenge because of the high torque of the handpiece and the inability to stop the rotating bur rapidly. (2) Low-speed electric handpieces are a significant improvement over low- speed air-driven hand-pieces, and they have replaced their air-driven predecessors in dental office. High- speed electric hand pieces offer some distinct advantages over air-rotor hand-pieces, but these advantages are less impressive than those observed with low-speed electric handpieces vs. air-rotor hand-pieces. Thus they do offer the advantages promoted for them, but at significant expense. Tooth preparation: All-ceramic crowns and a fixed prosthesis require deeper tooth preparations to allow for the thickness of zirconia substructures underneath the esthetic veneering ceramic. Manufacturers recommended a 0.3 mm thickness of zirconium oxide on anterior teeth and 0.5 mm thickness on posterior teeth. When one compares tooth preparations for zirconia-based prosthesis with those for conventional PFM prosthesis. The all-ceramic crowns require deeper tooth structure removal on the mesial, distal and lingual aspects of the praparation to achieve optimum thickness of substructure and veneering ceramic. As the popularity of all-ceramic restorations continues to increase, deeper tooth preparations will be used more frequently. This necessity probably will limit the use of all-ceramic crowns for younger patients who have larger pulps. (3) An axial and occlusal reduction of 0.8–1.0 and 2.0 mm respectively is required. To minimise stress concentration within the ultimate restoration and facilitate digitisation of the preparation, the use of sharp line angles, boxes, grooves and 'butt' type shoulders is contra-indicated and a medium, chamfered, axial reduction is required. For similar reasons it is important to round off all surface transitions and there must be no residual sharp edges to the preparation. To facilitate appropriate tooth preparation a set of customised diamond burs is available. (4) Preparation margins should be placed supragingivally wherever possible. The use of subgingival margins, e.g. for aesthetic reasons, should be restricted to the labial aspect of upper anterior teeth. This will not only simplify impression procedures but it will also help to maintain optimal periodontal health. (5,6)