comparing nano hybrid composite blocks with ceramic blocks in indirect restorations 2. protocol registration:

Conditions: the Clinical Performance of Indirect Restoration Fabricated From Nanohybrid Cad Cam Composite Blocks and Ceramic Blocks

Summary: comparing nano hybrid composite blocks grandio blocks (voco) with ceramic blocks (emax) in indirect restorations using modified usph criteria (marginal integrity) to see if there will be a significant different between two blocks

ceramic restorations are well - thought- out an excellent option to restore posterior teeth were esthetics is required and the size of the cavity preparation has surpassed the conventional for direct resin composites , ceramic systems can syndicate esthetics with wear resistance , being considered a consistent treatment of choice ,peutzfeld evaluated , the failure rate of different restorative materials used in posterior teeth and stated that gold inlays didnt present a much lower failure rate than ceramic or composite inlays, consequently , the author suggested that other aspects besides longevity , such as esthetics , charge and number of visits should also be considered when relating treatment options different ceramic systems for constructing inlays and onlays restorations are available in the market, some of the ceramic restorations are made using feldspathic ceramic , the cerec computer aided design/computer -aided manufacturing, cad/cam system or the hot-pressed leucite -reinforced ceramic fabricated by the conventional lost wax technique , other systems that employ alumina are available , there are three types of materials available for the dentist (glass ceramics /ceramics)resin hybrid ceramics and composite blocks advantages of ceramic restortations are improved because of their increased translucency and light transmission ,another advantage embraces minimal tooth reduction compared with metal ceramics , minimal thermal conductivity , they have desirable properties including their physical and mechanical properties , outstanding biocompatbility to periodontal tissues and less susceptibility to metal allergies though ceramic blocks will cause wear of opposing natural teeth ,expensive , that's why we have to shift to another material resin composite resin composite materials have been quickly developed in the last few years , direct resin composite restorations become the gold standard for restoring intra coronal cavities , while for the extra coronal cavities , the indirect resin composite onlays be inclined to replace metallic restorations in most situations being more esthetics and conservative with lower cost. one of the break throughs in resin composite technology is the evolution of the new resin composite blocks (grandio blocks ) merits of grandio blocks the highest fillers content ( 86% by weight)resembles natural teeth perfectly , excellent physical values for flexural strength and abrasion , no firing required (a real one step), can be processed using any conventional milling unit , can be polished and repaired optimally , ideal for grinding even incases with thin edges and its based on the nano hybrid technology .

Eligibility criteria:
inclusion criteria: * patients with badly broken vital teeth good oral hygiene measures young adults males or females cooperative patients approving to participate in the study exclusion criteria: * patients with compromised medical history lack of compliance severe medical condition severe or active periodontal disease