Photoelastic stress analysis around ultra short implant/monolithic zirconia crown with various occlusal load

Abstract Background The clinical application of ultra-short implants has been increasing. However, there is dearth of information regarding the stress around ultra-short implant/monolithic zirconia crown combination. Aim To determine photoelastic stress analysis around ultra-short implant/monolithic zirconia crowns with various occlusal load. Patients and methods 32 ultra-short implant fixtures with two different lengths (5 mm and 6 mm) were used. Each implant fixture was embedded into a photoelastic resin block. Stock straight titanium abutment was screwed to each fixture then zirconia crown was cemented for each abutment. Each model was positioned on a circular polariscope and subjected to axial and oblique load with various magnitudes. The polariscope images were recorded using digital camera, processed in a MATLAB environment, then stress was calculated at five predetermined points around each implant. Data was analyzed with three-way analysis of variance and Student t test (α=0.05). Results Analysis of measurement disclosed a significant difference for implant length and region and their interaction ( P <0.001). Also, there was a statistically significant difference between load magnitude and direction and their interaction ( P <0.001). Oblique load exhibited the highest stress regardless of implant length and load magnitude. Conclusion Ultra short implant/monolithic zirconia crown recorded less stress under axial load. However, oblique load was significantly more damaging.