Australian Dental Council (ADC) Practice Test

The ideal length for a post in a post-core for an endodontically treated tooth is generally accepted to be 1.5 times that of the crown. This principle is based on the need for the post to provide adequate retention and stability for the restorative material that will be placed on the tooth. Lengthening the post relative to the crown allows for a more secure anchoring in the remaining dentin, enhancing the overall strength of the restoration.

A post that is 1.5 times the height of the crown allows it to engage more tooth structure, distributing forces more effectively and helping to prevent fracture of the remaining tooth structure. Moreover, this length also minimizes the risk of overextending the post into the apical region of the root, which could damage the periapical tissues.

In contrast, the other options suggest lengths that may not adequately support the restoration. For example, a post that is merely half the tooth length may provide insufficient retention, while a length that is only two-thirds may also not engage as effectively with the remaining tooth structure compared to the ideal recommendation. Selecting a post length based on the anticipated crown alone does not take into consideration the stability and retention required from a scientific perspective, highlighting the importance of considering functional and biological factors