Effect of Surface-Polishing Techniques and Aging on The Roughness and Optical Properties of Different Ceramic-Polymer Systems : In-Vitro /

Abstract

Dental restorations should possess certain criteria and characteristics to be acceptable. Biocompatibility to oral tissues, resistance to fracture under masticatory forces and superior esthetic properties of the material are among the most important characteristics.

Dental ceramics are one of the most popular and successful fixed dental restorations because of their biocompatibility and optimal esthetic properties. Ceramics are included in the fabrication of fixed and removable tooth- and implant-supported prosthodontics. Dental ceramics can mimic natural tooth color, translucency and gloss. Ceramic restorations could be fabricated as one full contoured unit of the same material, referred as ‘monolithic”, or fabricated in the form of a material with higher strength as a substrate and veneered to a full contour with other ceramic material for esthetic purposes, then referred as “bilayered” ceramic restorations. The latter case, as zirconia substrate veneered with lithium disilicate or feldspathic porcelain, which combines both strength and high fracture resistance (zirconia substrate) and esthetics (lithium disilicate or feldspathic porcelain).

One of the main drawbacks of dental ceramics is their fracture tendency when subjected to tensile stresses. Polymer infiltrated ceramic materials have been introduced to the market to combine the advantages of both ceramics and resins to overcome some of the mechanical drawbacks of ceramics. 3–6

The innovation in computer aided design/computer aided manufacturing (CAD/CAM) systems has a motivating influence in developing new ceramic blocks. Accuracy, time-saving and superior esthetics are benefits gained of these new products. Polymer infiltrated ceramic CAD/CAM blocks have been recently introduced as a chairside restorative material.7,8 Manufacturers claim that the polymer integrated within the ceramic structure would provide elasticity to the restoration.9 Hybrid ceramic restorations can be used as anterior and posterior single tooth- or implant-supported restorations.

The construction of hybrid polymer ceramics is a one-step CAD/CAM procedure, which means, they do not need a heat treatment or furnace for setting or sintering. Moreover, no need for heat glazing or even a glaze layer to be applied as claimed by the manufacturers.

Esthetic consideration of newly introduced materials is an important factor to determine the acceptance and durability. The importance of polishing procedure and aging of polymer-ceramic materials and their effect on the surface roughness, consequently the optical properties, are the objectives of this study.