fundamentals of fixed prosthodontics 5th edition pdf

Johnston suggested 5–7° (10–14° CA) and Kronfeld accepted a range that includes all these figures. state that the ideal taper is 2° on anterior teeth and 2–5° on the posterior teeth. recommended a 6 degree (°) taper, which gives a convergence of 12° as ideal Tylman et al.

Various angles have been proposed as ideal in textbooks Shillinburg et al. CA is inversely proportional to the retention, with greater angles reducing the retention of crowns. It gives marginal and internal adaptation for the crowns and can be controlled by the operator. Thus, CA, the angle between two opposing axial walls that equals the sum of the taper (angle between one axial wall and the long axis of the preparation) of two opposing axial walls of a preparation, is considered as a prime variable. The length and diameter of the preparations are often limited by the existing dental anatomy and improved retention due to cement depends upon mechanical interlocking of cement, surface area of cement coverage, durability of cement, resistance to mechanical breakdown and dissolution. It is proposed to be influenced by factors such as height and diameter of the preparation, luting cement and predominantly by one of the operator controlled factors, convergence angle (CA). However, one property of cement retained fixed restorations, retention, has been of prime importance in all designs. Crowns and fixed partial dentures (FPDs) are the major prosthodontic treatment modalities for past several decades with factors like esthetics, contact points and pontics playing an important role in varying their design.

Fundamentals of fixed prosthodontics 5th edition pdf