ABSTRACT
OBJECTIVE@#To evaluate the effects of different edge compensation angles on the fracture strength of multilayer zirconia all-ceramic crowns and traditional uniform zirconia all-ceramic crowns.@*METHODS@#The resin tooth preparation specimen of the mandibular first molar with a knife-edge was fabricated. A 3D digital model of the specimen was obtained by scanning it with a 3D dental model scanner. The 3D digital model was imported into computer aided design (CAD) software, and three 3D digital models of the full crown with the same surface shape are designed with the edge compensation angles of 30°, 45° and 60°, respectively. Then, the designed 3D digital model is imported into computer aided manufacturing (CAM) software. Three kinds of multilayer and homogeneous zirconia all-porcelain crowns with different edge compensation angles were fabricated, 10 each for a total of 60. The fracture load of each crown was measured under the electronic universal testing machine.@*RESULTS@#Fracture load of multilayer and uniform zirconia all-ceramic crowns, (4 322.86±610.07) N and (5 914.12±596.80) N in the 30° group, (5 264.82±883.76) N and (5 220.83±563.38) N in the 45° group and (4 900.42±345.41) N and (5 050.22±560.24) N in the 60° group, respectively. The fracture load of multi-layer zirconia all-ceramic crowns in the 30° group was significantly lower than that of homogeneous zirconia all-ceramic crowns(P < 0.05); there was no statistical significance in 45° group and 60° group(P>0.05). In the multi-layer zirconia all-ceramic crowns: the fracture load of the 30° group was significantly lower than that of the 45° group (P < 0.05); there was no significant difference between the 30° group and the 60° group, the 45° group and the 60° group (P>0.05).In uniform zirconia full crown group: the 30° group was higher than the 45° group, the 30° group was higher than the 60° group (P < 0.05), and there was no significant difference between the 45° group and the 60° group (P>0.05).@*CONCLUSION@#The fracture loads of three kinds of uniform and multilayer zirconia all ceramic crowns with different edge compensation angles can meet the clinical requirements. A smaller edge compensation angle is recommended when using traditional zirconia all-ceramic crowns, while 45° is recommended when using multi-layer zirconia all-ceramic crowns.
Subject(s)
Ceramics , Computer-Aided Design , Crowns , Dental Porcelain , Dental Prosthesis Design , Dental Restoration Failure , Dental Stress Analysis , Flexural Strength , Materials Testing , ZirconiumABSTRACT
Objective@#To investigate the reliability of using virtual articulator in the fabrication of zirconia crowns for tetracycline discolored teeth.@*Methods@#To treat the patient with serious tetracycline stained teeth, we use zirconia crowns to shield the stained abutment teeth. To retain the characteristics of patient′s original occlusal contacts, meanwhile, to establish a stable and evenly distributed occlusal contacts, we recorded the functional movements of the patient′s jaw before preparing the teeth and transferred this relations to a physical articulator. Afterwards, relationship of the upper and lower arches was scanned through a specified fixature. Then we can customized the fabrication of the occlusal contacts of the restorations conveniently and efficiently with virtual articulator in CAD/CAM system.@*Results@#When the final restorations were inserted , a charming smile was achieved on patient′s face with satisfactory esthetics. With the application of virtual articulator in designing process, we made evenly distributed and stable bilateral occlusal contacting spots, smooth protrusive and lateral guidance on the lingual aspects of the upper anteriors. One year follow-up, this patient was observed in good oral hygiene, and was satisfied with her esthetic and functional outcome. The soft tissue around the restorations was assessed to be healthy and no signs of inflammation.@*Conclusion@# Applying the virtual articulator kits in CAD/CAM system in designing and fabricating the function-driven restorations could be an efficient way to obtain an satisfactory long-term outcome.
ABSTRACT
Earlier Metal ceramic crowns were the restorations of choice in the management of traumatic tooth fractures. However, the inherent drawbacks of metal ceramic restorations and the development of newer all ceramic alternatives have resulted in superior esthetic and functional management of these clinical situations. The following case series describes the management of traumatic tooth fractures with Zirconia based all ceramic restorations following endodontic therapy.