Schlottke, SaeEun2016-09-192016-09-192016-05https://hdl.handle.net/11299/182104University of Minnesota M.S. thesis. May 2016. Major: Dentistry. Advisor: Heather Conrad. 1 computer file (PDF); vii, 50 pages.Purpose This in-vitro study was designed from a clinical case and investigated how mechanical and chemical changes on implant abutment surfaces would result in different tensile strengths between computer-aided design/computer-aided manufactured lithium disilicate crowns and implant abutments. Material & Methods A clinical case master cast of a maxillary right central incisor single implant restoration was utilized to fabricate five different abutment types: titanium smooth surface (Ts), titanium with retentive grooves (Tr), titanium with titanium nitride coating without grooves (Gs), titanium with titanium nitride coating with retentive feature (Gr), and zirconia(Z). A total of 50 lithium disilicate crowns were fabricated and equally divided into five groups. The maximum tensile strength of each combination was measured using a universal testing machine until the interface failed. Results The rank of mean retention value was found from highest to lowest, titanium with titanium nitride coating with grooves (Gr), titanium with titanium nitride coating without grooves (Gs), titanium with retentive grooves (Tr), titanium without retentive grooves (Ts), and zirconia (Z). One-way ANOVA analysis indicated the retention value of the Gr has statistically significant difference compared to all other groups (p <0.05). Gs and Gr both significantly improved retention compared to Z group (p value <0.05). No statistically significant differences were found between other pairs of groups in terms of retentiveness. Conclusion The retentive grooves or titanium nitride coating on titanium alloy abutments alone did not significantly increase retention, but when they were used together, there was substantial improvement in retention. Titanium with titanium nitride coating in conjunction with retentive grooves can significantly improve the surface retention compared to a zirconia abutment. This data can be used by clinicians in clinical decision- making when additional retention is desired in the esthetically challenged regions such as the anterior maxilla.encustom abutmentimplanttensile strengthThesis or Dissertation