Statement of problem: For patients with limited interocclusal space, standard height implant abutments may not be usable. Shorter abutments may be desirable.
Purpose: The purpose of this study was to determine the effect of the height of titanium abutments on the tensile strength required to dislodge zirconia copings.
Material and methods: Two experimental groups of abutments were prepared: (1) 4.3-mm platform width implant abutment with a 6.5-mm height (control), and (2) a 4.3-mm platform width implant abutment with a 5.5-mm height (shorter). Each abutment had 5 zirconia copings (custom designed) fabricated through a 3-dimensional computer-assisted design (3-D CAD) process by scanning an identical wax pattern. The zirconia copings were designed to have a 6-mm projection above the titanium abutment to accommodate a 2-mm hole. A wire was inserted through this hole to attach the zirconia coping to a universal testing machine. Each abutment was placed onto an implant embedded in a brass base designed to fit onto the universal testing machine. The zirconia copings were cemented onto the abutments with a provisional luting agent (Improv), and a tensile force was applied at a crosshead speed of 0.5 mm/min. The removal force was recorded for each specimen. An unpaired t test was used for the statistical analysis (alpha =.05).
Results: The mean force (SD) necessary to remove the zirconia copings (Newtons) from the 6.5-mm titanium abutment (198.09 (28.83)) was higher (P=.0078) than for the 5.5-mm abutment (124.89 (36.388)).
Conclusions: By increasing the height of the abutment 1 mm and maintaining the diameter of the abutment, the resistance to tensile forces increased significantly between the 2 abutment dimensions evaluated.