| The wedge-shaped defect is the common diseases and frequently encountered diseases of the department of stomatology, that has a predilection in the canines and premolars.The all important purpose of repairing the wedge-shaped defect are elimination of dentine hypersensitivity symptoms,restore the shape of tooth and improving the strength of restorations. It should be possible to enhance the retention force of restorations and prevent complications, in addition to considering the patients, aesthetic requirements.Due to many factors influence, such as the filling materials itself, clinical operations and occlusion force etc., it can often encounter restorations,falling off, discoloration, causing secondary caries and other issues. These directly affect the result of repair.Therefore,it is always one of the important issues that oral doctors discuss, in the premise that how to ensure the resumption of shape of teeth,and can enhance their retention force and reduce complications.The casting glass-ceramic has been used in defect of teeth in 1987.It has excellent biocompatibility , superordinary corrosion resistance and wear resistance.Especially its unique aesthetic property which is second to none compared with metal materials and other giant molecule materials. It has great compressive strength, high strength, small contractibility and tight marginalfitness. The restoration with casting glass-ceramic has proximal transparent rate compared with dental enamel. Its color is close to the natural teeth, on account of the material contains fluorescence.And the use of color cement,causing restoration is almost the same appearance and color with natural teeth to achieve the best aesthetic effect. Its physical and chemical disposition are stable, conductibility is bad. And the bacteria plaque is difficult to cohere. So it has been an important material for odontal restoration.This clinical study aims at questions such as the obturator falling off, discoloration and the secondary caries after repairing the wedge-shaped defect, chosen 23 cases that patients require to repair the wedge-shaped defect again, the number of teeth is 27 (both canines and premolars),which are all with casting glass-ceramic inlays. In the period of 3-12 months follow-up, we inquested patients the subjective evaluation about the inlays and had a clinical examination.Meanwhile, 24 ex vivo teeth with wedge-shaped defect were selected (both canines and premolars),and were divided into 2 groups randomly, 12 teeth per group.In accordance with the requirement of casting glass-ceramic inlay for each teeth preparation,repair the wedge-shaped defect with casting glass-ceramic inlay and light-cured composite resin respectively for dislocation strength test.There are 27 teeth in 23 cases which patients request to repair the wedge-shaped defect again.There are 14 cases since the original obturators falling off,the number of teeth is 15.There are 6 cases because of the secondary caries,the number of teeth is 8.There are 3 cases due to be unsatisfied with the color of existing restoration,the number of teeth is 4.This research uses the IPS Empress II casting glass-ceramic inlay of Liechtenstein Ivoclar-Vivadent Corporation.In accordance with the requirement of casting glass-ceramic inlay prepare the teeth.After having the impression with methyl silicone rubber,make manufacture the inlays.When try-in is suitable , bond the inlay with Provilinek light-cure multifunction resin binder.In the period of 3-12 months follow-up,all patients were satisfied with the shape and color of restorations,without discomfort.In the 20 rechecked cases including 23 restorations 12 months later,other restorations had well retention force,tight marginal fitness,no secondary caries and gingival inflammation,without cinch phenomenon,except for 1 restoration falling off because it is not strictly preventing from water in the bonding process.24 ex vivo teeth with wedge-shaped defect are divided into 2 groups randomly,which are with casting glass-ceramic inlay and light-cured composite resin respectively.After determining the dislocation strength with the electronicuniversal test machine, the t test shows that the difference had distinct significance between them, it reveals that the retention force of the casting glass-ceramic inlay is higher than the light-cured composite resin(P<0.01). The retention force of the casting glass-ceramic inlay is greater.Through the clinical research,we get the conclusion that the casting glass-ceramic inlay,which is almost the same appearance and color with natural teeth,having better aesthetic effect and excellent biocompatibility,has a better prospect.Because of its high strength,small contractibility,tight marginal fitness,it greatly reduces the incidence rate of the secondary caries.It profits the health of teeth.And the retention force of the casting glass-ceramic inlay is greater, not easy to fall off. Higher technology level is required to dentists and technicians , when repair the wedge-shaped defect with the casting glass-ceramic inlay.Although the casting glass-ceramic inlay has many advantages,its clinical application still has some limitations.First,the indication should be controlled strictly;second,the higher cost of the casting glass-ceramic inlay limits its application and promotion.With the development of national economy, people,s income and medical treatment level will be continuously improved, the applied prospect of casting glass-ceramic inlay will certainly be broader andbroader.
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