2018 Volume 31 Issue 4 Pages 330-337
Purpose : When complications, it is not easy to remove a cement-retained superstructure. Temporary cement is used to avoid such problems, and its application is becoming more versatile. Therefore, to overcome the disadvantages of the conventional removal method, we formed a slot hole on the interface between the crown and abutment using the electrical discharge method, inserted an angled removal tool exerting a wedge effect, and determined whether the crown attached using temporary cement can be removed from the abutment using a clinically applicable method.
Method : We then formed an original slot by die-sinking a box shape for the original removal tool. This was formed in the intermediate section on the lingual side between the frame of the superstructure and the abutment using an electrical discharge machine. The superstructure was attached using cement, and inserted the two types of removal tool (angle of 18° and 24°) inside the slot and checked if the superstructure could be removed. Multiple comparison tests were used to compare the bonding strengths and thickness of the cement films.
Results : Comparison between the two types of angled removal tool with different angles showed that the tool with an angle of 24° can produce a wedge effect with any cement and separate the copings with a smaller load than the removal tool with an angle of 18° (t-test, p＜0.01). The cement film was the thinnest in TB and the thickest in TH. There was no significant difference between TB and TP.
Conclusions : This removal method can expand the scope of application of electrical discharging in the dental field and can be recognized as an innovative method for the fabrication of cemented superstructures. From a clinical viewpoint, cements with high bonding strengths and thin film thicknesses, such as IP and FT, are considered to be ideal.
