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Effect of retention design of artificial teeth and implant-supported titanium CAD-CAM structures on fracture
Kristin Ladetzki1, Rocío Mateos-Palacios1, Agustín Pascual-Moscardó2
1Prosthodontics and Occlusion, University of Valencia, Valencia, Spain.
Background:
For implant-supported hybrid prostheses, high mastication forces and reduced acrylic resin thickness over a metal substructure often cause failures arising from tooth or resin fractures. To assay fracture resistance of artificial teeth and resin in implant-supported hybrid prostheses in relation to the titanium structure and retention design supporting teeth.
Material And Methods:
40 specimens bearing incisors were divided into four groups according to the titanium structure supporting the teeth and the type of load force applied: Group I (Control; n=10): Application of static loading to ten incisors set over a metal structure with internal retention. Group II (Control; n=10): Application of static loading to ten incisors set over a metal structure with external retention. The remaining study specimens (n=20) were subjected to 120,000 masticatory and thermal cycles in a chewing simulator. Afterwards, static loading was applied until the point of fracture using an Instron machine. Group III (Study; n=10): Application of dynamic and static loading to ten incisors set over a metal structure with internal retention. Group IV (Study; n=10): Application of dynamic and static loading to ten incisors set over a metal structure with external retention. Data obtained for the four groups was analyzed and compared, determining the type of fracture (cohesive or adhesive) using a reflected light microscope.
Results:
Statistical analysis confirmed that there were significant differences in fracture resistance between the four groups. External retention was found to have more fracture resistance than the internal retention.
Conclusions:
Hybrid prostheses with titanium substructures and external retention obtained significantly better results than samples with internal retention.
Key Words:
Chewing simulator, thermocycler, fatigue, implant-supported hybrid prosthesis, acrylic teeth, fracture, metal structure design.
