Experimental And Clinical Studies On The Bonding Performance To CAD/CAM Feldspathic All Ceramic Restoration

Tooth defect is common and frequently-occurring disease of human being,People need for restorations and treatments of inlay,crown and bridge. Traditional production processes are time-consuming, patients have to take many appointments to complete treatment.The technology of CAD/CAM which integrates with mathematics,optics,electronic technology,image recognition and processing,automatic control and manufacture has advantages with precise,rapid,efficient and single visit.The most representative CAD/CAM chairside dental restoration system is CEREC,which can fabricate all ceramic restorations in a single visit.Feldspathic machinable ceramic blocks are used in CEREC.The restorations are bonded to dental tissues with resin cement,the bond performance between feldspathic ceramic and resin cement is greatly meanful for the durability and fine function. Vita MarkⅡblock and four types of resin cements are selected in the present study(RelyX Veneer,Panavia F,RelyX Unicem,FL-BOND+Beautifil Flow).The purpose of this study was to evaluate the effects of different ceramic surface treatments and thermo-cycling on the bonding strength and bonding interfaces between feldspathic machinable ceramic and four types of resin cements.Eighty-six restorations are assessed using modified USPHS criteria.The results from this study could present to provide some references for clinic procedures.According to the results,the following conclusions could be achieved.1.The bonding strength of silicane group utilizing four types of resin cements were 12.18±2.86 MPa,12.47±3.54 MPa,11.71±3.14 MPa,7.27±3.13 MPa,which were significant lower than the acid group(15.26±3.02 MPa,16.72±3.10 MPa,15.53±3.47 MPa,10.68±3.22 MPa),it illustrated that simple chemical combination was weak,higher bonding strength could be achieved to mechanical combination.2.The highest bonding strength can be seen in alliance group,they were 20.61±2.89 MPa,22.02±4.03 MPa,20.50±3.18 MPa,18.96±2.73 MPa,it can be conclude that alliance of silicane and acid significantly enhance the bonding strength of feldspathic machinable ceramic.SEM observation revealed that bonding interfaces of alliance group were dense between ceramic and resin cement.3. The shear bond strengths of the groups of RelyX Veneer,RelyX Unicem and FL-BOND+Beautifil Flow dropped markedly from 19.86±3.39MPa,20.66±3.08MPa,21.18±3.30MPa to 16.42±1.90MPa,16.28±3.45MPa and 13.29±2.47MPa after thermo-cycling of 5,000 cycles.Panavia F showed the greatest bond strength after thermocycling among the four resin cements used. 4. According to modified USPHS criteria after one year,the restorations which reached Alpha were 85.7% in marginal adaptation,83.9% in anatomic form,88.9% in surface texture,85.7% in color match.There was no significant difference between four types of resin cements.