Assessment of Undercuts Relative to Abutment Teeth and Edentulous Area: A Retrospective Cross-sectional Study

Undercuts on abutment teeth (AT) should be identified and quantified to establish the exact location of the active tip of the retentive arm of the direct retainer. The aim of this study was to locate and evaluate tissue and tooth undercut areas in various Kennedy's classes and to assess the correlation, if any, between Kennedy's classes and the location and depth of undercuts. One hundred and seven patients' casts, with designated AT and edentulous areas (EAs), were surveyed. The undercuts on AT and EAs were measured using undercut gauges. Statistical analysis was performed. The median depth of the undercut was maximum on distal the surface of mandibular AT in a Kennedy's class III edentulous situation. No significant difference was found between the amount of tissue undercuts measured on the EA in each of the Kennedy's classes in the maxillary and mandibular arches. No significant difference was found between the amounts of undercut measured on AT and the EA in each of the Kennedy's classes in the maxillary and mandibular arches. No correlation was found between Kennedy's classes and the location and depth of undercuts. The results of our study reinforce that the diagnosis and selection of ideal abutments should be stressed while planning for a removable dental prosthesis (RDP). In the majority of the cases, the anticipated design of the direct retainer can be applied, though one cannot overlook the need for proper diagnosis and survey.