IADR Abstract Archives
Fracture Resistance of Additively Manufactured All-Ceramic Crowns with Graded Structure
Objectives: The objective of this study was to replicate the graded structural design of a natural tooth in an implant-supported all ceramic crown in order to improve their fracture resistance by using additive manufacturing (AM) technologies. The purpose of this in vitro study was to compare the fracture resistance of implant-supported milled zirconia, milled lithium disilicate, AM zirconia and AM graded structural zirconia crowns.
Methods: A maxillary cast with a dental implant replacing right second bicuspid was obtained. A zirconia custom abutment was milled and a full-contour crown was digitally designed. The STL file was used to fabricate 10 crowns for each group. A total of four groups, milled zirconia (MZr), milled lithium disilicate (MLD), AM zirconia (AMZr) and AM zirconia with graded structure (AMGS) were included in the study. The crowns were cemented to implant-supported zirconia abutments in accordance with the manufacturer’s guidelines and mounted on polyurethane foam blocks. The fracture resistance was determined for all the groups by vertical force application using a computer controlled universal testing machine at a crosshead speed of 2mm/min. The data were analyzed with Kruskal-Wallis tests (α=0.05) and the mode of failure was determined for all the groups.
Results: Milled zirconia revealed the highest mean value for fracture resistance (1330±111 N), followed by milled lithium disilicate (1257±169 N), Additively manufactures zirconia (1179±247 N) and additively manufactured zirconia with graded structural design. However statistical analysis showed no significant differences in fracture resistance between the groups (p>0.05). All samples fractured at zirconia implant abutment in all the groups.
Conclusions: Within the limitations of this in vitro study, it can be concluded that AM all-ceramic crowns with and without a graded structural design demonstrated similar fracture resistance to milled all- ceramic crowns when cemented to implant supported zirconia abutments.
Methods: A maxillary cast with a dental implant replacing right second bicuspid was obtained. A zirconia custom abutment was milled and a full-contour crown was digitally designed. The STL file was used to fabricate 10 crowns for each group. A total of four groups, milled zirconia (MZr), milled lithium disilicate (MLD), AM zirconia (AMZr) and AM zirconia with graded structure (AMGS) were included in the study. The crowns were cemented to implant-supported zirconia abutments in accordance with the manufacturer’s guidelines and mounted on polyurethane foam blocks. The fracture resistance was determined for all the groups by vertical force application using a computer controlled universal testing machine at a crosshead speed of 2mm/min. The data were analyzed with Kruskal-Wallis tests (α=0.05) and the mode of failure was determined for all the groups.
Results: Milled zirconia revealed the highest mean value for fracture resistance (1330±111 N), followed by milled lithium disilicate (1257±169 N), Additively manufactures zirconia (1179±247 N) and additively manufactured zirconia with graded structural design. However statistical analysis showed no significant differences in fracture resistance between the groups (p>0.05). All samples fractured at zirconia implant abutment in all the groups.
Conclusions: Within the limitations of this in vitro study, it can be concluded that AM all-ceramic crowns with and without a graded structural design demonstrated similar fracture resistance to milled all- ceramic crowns when cemented to implant supported zirconia abutments.
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