(…) Ceramic materials have made considerable technological progress : the evolutions in technology, the aesthetic needs of patients, and the rising awareness of biocompatibility have led to the development of more resistant materials better suited to the creation of natural looking teeth. In certain cases, it is now possible to replace traditional ceramo-metallic restorations by ceramo-ceramic restorations.
III. THEORETICAL ADVANTAGES AND DISADVANTAGES OF CERAMO-CERAMICSS
The ceramics used in prosthetic odontology are bio-inert materials (chemical, electric and thermal inertia). They are more stable than metals and resins, they do not corrode or degrade, and this chemical stability minimises the reactions of the organism. Thermal inertia allows the isolation of the pulpo-dentinal complex and the assembly materials from variations in temperature.
The good periodontal tolerance of ceramics is enhanced by the absence of metal which prevents systemic resorption of the gingival crevice, and a marginal periodontium attack.
Unlike metals, ceramics are materials with a fragile breaking point, ie breaking without previous distortion. The resistance to fracture from the propagation of a crack defines the tenacity of the materials and differs according to their constitution. The classification in increasing order of resistance to the biaxial flex of the principle ceramo-ceramics systems is the following: Empress II® (350), In-Ceram Spinell® (350), In-Ceram Alumina® (500), In-Ceram Zirconia® (700), Procera Alumine® (700) and Y- TZP® (1100). These mechanical differences have clinical implications and orient the use of the materials.
The choice of dental ceramic rests upon its mechanical properties, but also on the basis of aesthetic requirements.
The natural appearance of ceramo-ceramic crowns is an advantage in comparison to the aesthetic and electrochemical shortcomings of metallic materials (corrosion, metal edge sometimes visible following gum recession, loss of transparency and weak light dispersing properties, darkening of tissues at the cervical level). (…)
Written on the 15th of September 2006