|Retentive Strength of a Custom Hexagonal Abutment and its Clinical Applications|
A hexagonally shaped abutment, with or without modification, can be used in different clinical applications. A prefabricated castable coping designed to fit the hexagonal shape of the abutment and its shouldered margin was cemented to a hexagonal abutment. Pullout tests were used to evaluate retentive strength of the cemented coping in unmodified and modified forms. The unmodified hexagonal abutment with 3mm high parallel walls produced the highest retentive strength. Removal of one of the hexagonal surfaces maintained 80% of the retentive strength. Further removal of the second and third adjacent surfaces produced no significant reduction in retentive strength. Removal of the remaining three surfaces produced a cylindrical abutment, which demonstrated the weakest retentive strength.
1. Assif D, Azoulay S, Gorfil G. The degree of zinc phosphate cement coverage of complete crown preparations and its effect on crown retention. J Prosthet Dent 1992;68:275-278.