Which clasp type would likely provide inadequate retention for posterior edentulous areas?

The infrabulge clasp is considered to provide inadequate retention for posterior edentulous areas due to its design and placement. This type of clasp engages an undercut area that is typically found on the buccal surface of the teeth, which is more effective for anterior and some upper posterior applications. In the case of posterior edentulous spaces, particularly in lower jaw situations, the required retention is less effective because the clasp does not adequately encompass the tooth in the manner needed to maintain a secure fit against the forces of dislodgement that are common in the posterior regions.

Additionally, posterior edentulous areas often require a higher degree of retention and support, which is generally better provided by clasps that are more circular and engage more of the tooth surface or utilize vertical projection elements to grasp and hold. Other clasp designs such as vertical projection or simple circlet clasps can provide more direct resistance against the forces acting on the denture, thereby enhancing their retention in situations involving posterior teeth.