Abstract
BackgroundFor 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 Methods40 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.ResultsStatistical 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.ConclusionsHybrid 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.
Highlights
The number of edentulous patients has declined in recent decades, dentists will always have to treat patients in need of complete rehabilitation resulting from periodontal disease, multiple caries and other causes [1,2,3]
Ted by means of the chewing simulator and thermocycler showed lower resistance to fracture than their respective control groups
After subjecting samples to static loading, cohesive fractures were detected in all Type B design specimens, which showed that there was a close union between the prosthesis’s artificial teeth, resin base and metal structure (Fig. 2B)
Summary
The number of edentulous patients has declined in recent decades, dentists will always have to treat patients in need of complete rehabilitation resulting from periodontal disease, multiple caries and other causes [1,2,3]. Hybrid prosthetics are generally understood as an implant-supported complete prosthesis screwed onto a minimum of four implants They consist of a metal substructure covered by resin and acrylic teeth. The main aim of this study was to analyze the behavior of artificial teeth set upon titanium substructures in implantsupported hybrid prostheses, assaying fracture resistance in relation to the design of the metal structure (internal or external retention) bearing the teeth. 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. Conclusions: Hybrid prostheses with titanium substructures and external retention obtained significantly better results than samples with internal retention
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