The Clinical Study Of The Chairside CAD/CAM Made Restorations

The chairside CAD/CAM system is a trend of stomatology ,because it is a dental restoration system that allow dental professionals to deliver high-quality esthetic and presise restorations to their patients at chairside without laboratory intervention. At present, in China, the application of it is not that extensive for kinds of reasons. The more appliance of CAD/CAM technology is the design and manufacture of aluminum-oxide and Y-TZP based FPD frameworks in laboratory which are not that proficient for making a restoration.The high cost of the machinable ceramic blocks is one of the main reasons that limit the application of the chairside CAD/CAM system. These machinable ceramic blocks now are all made abroad and very expensive. Furthermore, the restoration made by it has long been thought to be formed in a process meaning that once it has a fault, it has no remedy and has to be disposed. The cost then is increased much. Therefore, cutting down the cost of material is the key to this problem.This issue is composed of three experiments. First, make a 8-year follow-up study of 24 Cerec2 CAD/CAM all-ceramic crowns to evaluate their clinical performances, which can be the base for the further study. Second, investigate shear bond strength between Vitablocs markⅡand four kinds of commercial veneering ceramics so as to find a suitable veneering ceramics to make up the imperfect restorations. Thrid, make restorations of Vitablocs Mark II and make a short-term follow-up study so as to accumulate the operation experiences for further extensive application. At the same time, try to make restorations of self-made ceramic blocks to evaluate their clinical applicability.Experimental results1. After the 8-year follow-up, 3 of the 24 restorations failed as results of ceramic crack, loosing and extraction of the abutment teeth, root fracture of the abutment teeth. The failed occurred respectively at 2 months, 43 months and 53 months after restoration and all the failed cases'abutments are molor. While 86% of the other 21 restorations'marginal fitness, surface texture, shape and color which still function well achieve the standard of level A. The results of the satisfaction questionnaires show that all the targets'satisfaction rates achieve 100% except the expenses. According to Kalplan - meier analysis, the success rate of Cerec2 crowns was 87.5% after 8 years'function in oral.2. the shear bond strengths of four groups of E-max ceram,Vintage ZR,Cercon ceram kiss,Vita VM9 are 41.07±12.42,43.44±11.32,35.81±8.69,37.35±9.71(MPa) respectively .More than 67% of the specimens′fracture originated and propagated in the base ceramics .The result of one-way ANOVA (F=0.641,P>0.05 )shows that there is no statistic differences among the data of four groups. Comparing with ISO9693: 1999 standard using one group t-test, all of the data of the four groups were higher than the standard. The results of SEM showed that the combination interface between 4 kinds of veneering porcelain and base porcelain are smooth without obvious air bubbles and therefore can indicate a satisfied combination.3. 27 Cerec restorations were fabricated using the Vitablocs Mark II ceramic blocks, of which three restorations failed as results of ceramic crack and crown fracture of the abutment teeth. The failed occurred respectively at 1 month, 3 months and 4 months after restoration. The results of the satisfaction questionnaires show that all the targets'satisfaction rates achieve 100%. While more than 87% of the restorations'marginal fitness, surface texture, shape and color which still function well after one-year follow-up achieve the standard of level A. 4 Cerec restorations were fabricated using the self-made ceramic blocks. 2 restorations failed during the veneering and staining process, the cause may be the unsuitable sintering temperature or the dismatching between veneering porcelain and base porcelain. The other two restorations without veneering and staining still function well after more than two-month follow-up.Conclusion1. The Cerec2 chairside CAD/CAM system can allow dental professionals to deliver high-quality esthetic and presise restorations to their patients at chairside without laboratory intervention. The only shortcoming of the restoration is the occlusion appearance which need to be modified.2. The data of the shear bond strength between Vitablocs markⅡand four kinds of commercial veneering ceramics are higher enough to meet the requirement of clinic use. All of the four kinds of veneered porcelain can be used as the individual character veneering ceramics for Vitablocs markⅡ. 3. The crowns of Vitablocs markⅡmade by Cerec2 CAD/CAM system can be kept in oral and function well for many years.4. Comparing with the Vitablocs Mark II ceramic blocks, the self-made ceramic blocks have satisfied artherectomy ability, but unsatisfied color which need to be improved in the further study.