Maintaining retained infra-occluded primary molars in hypodontia patients to reduce surgical complexity of dental implant surgery: a retrospective study

Abstract

Introduction When a permanent premolar is absent, the ultimate treatment goal is often replacement with an implant-retained restoration. Before this, the retained primary molar (RPM) may undergo infra-occlusion and be extracted early. This retrospective study looked at the influence of early extraction or maintenance and restoration of RPMs on the requirement for grafting in the implant site. Patients and methods From a large cohort of implant recipients, 273 RPMs from 84 patients were replaced with implants and the interventions before implant placement recorded. Results The most common RPM was the lower second primary molar and 189 (69%) had some degree of infra-occlusion. Additionally, 47 (17%) of RPMs were extracted early, and this was significantly associated with the need for grafting at the implant site (p <0.00001). Sinus lifts were not associated with early RPM extraction. Also, 25 infra-occluded RPMs were restored with onlays, but this had no ultimate influence on grafting at the implant site. Conclusion Maintenance of an RPM with no permanent successor, even when infra-occluded, has a significant beneficial effect on preserving bone volume for implant placement.