Mandibular Overdenture Performance with Conventional and Immediate Loading: 1-year RCT

Objectives: To evaluate the clinical, biological, functional, and oral health related quality of life (OHRQOL) influence of conventional (CL) and immediate (IML) loading in mandibular overdentures retained by narrow diameter implants (NDI) up to one year after implant installation.
Methods: Twenty edentulous patients received 2 NDI (Facility Ø2.9 mm) in the mandible; the loading type (CL or IML) was randomized. The clinical peri-implant health indices were monitored, along with prosthetic events, marginal bone loss/change, implant stability quotients (ISQ), masticatory performance (MP) outcomes (before, 1, 3, and 12 months), and IL-1β and TNF-α levels in the peri-implant crevicular fluid (3, 6, and 12 months). The OHRQoL was assessed via the OHIP-EDENT questionnaire before, 3 and 12 months after loading. Data were analyzed by the Mann-Whitney, Chi², Wilcoxon paired and McNemar tests.
Results: At 3 months, the ISQ in the CL group (50.6) was significantly lower than in the IML group (54.25; P=0.018). The probing depth at 12 months was significantly higher in the CL group (2.19 mm) than in the IML group (1.29 mm; P≤ 0.0001). TNF-α was 33.6% higher in the CL group at 6 months (P=0.043), while IL-1β was significantly higher in the IML group up to 6 months. No significant differences in marginal bone loss/change, MP and OHRQoL outcomes were observed. The survival rate was 90% in the CL group (2 losses) and 85% in the IML group (3 losses); 33 prosthetic events occurred in the CL group and 23 in the IML group: primarily equator dislodgement, followed by abutment replacement.
Conclusions: Both loading protocols are viable, however, IML generates better adaptation of the peri-implant tissues around the prosthetic components, reflected in a smaller probing depth and fewer prosthetic events. Improvement in masticatory function and OHRQoL was not affected by the type of occlusal loading.