Adhesion properties of modified cement-retained implant prostheses: In vitro mechanical tensile experiments and computational fluid dynamics analyses

Abstract Statement of problem The adhesion properties of modified cement-retained implant prostheses have not been elucidated. Purpose The purpose of this in vitro study was to compare the adhesion strength and the flow conditions of the adhesives of 3 common modified cement-retained methods (MCRMs). Material and methods Four cement-retained methods were used: an occlusal hole for screw access (OH), a lingual hole for releasing the excess adhesive (LH), a resin replica for the titanium abutment (RR), and a control group (no holes and no resin trial abutments). Eight zirconia prostheses in each group were processed and cemented. The adhesion strength was examined by mechanical tensile experiments (MTE) in vitro. One-way ANOVA and the LSD post hoc tests were used to compare the results of the MTE (α=.05). The flow conditions of adhesives in the adhesion process were analyzed by computational fluid dynamics (CFD). CFD-Post 16.0 (ANSYS, Inc) was used to analyze the results of the CFD analyses. Results The adhesion strength of each group was 289.3 ±37.7 N in the LH group, 281.3 ±50.1 N in the OH group, 263.3 ±49.3 N in the RR group, and 239.2 ±29.4 N in the control group. A statistically significant difference is seen in the adhesion strength between the LH group and the control group (P=.025). The internal filling ratio of adhesives between the groups ranges from high to low in the order the LH group, the OH group, the RR group, and the control group. The amount of cervical overflow of adhesives between the groups ranges from less to more in the order the RR group, the OH group, the LH group, and the control group. Conclusions MCRMs can effectively reduce the amount of cervical overflow of adhesives and improve the filling condition of the adhesive and its clearance to ensure the adhesion strength of the prostheses.