Purpose: The aim of this clinical study was to verify the predictability of the rehabilitation of extremely atrophic jaws with immediately loaded short implants and evaluate posterior mandibular regrowth.
Materials and methods: A cohort of consecutive fully edentulous patients wearing complete dentures in both arches was enrolled. Periodically, implant survival and prosthetic success were assessed. After informed consent, a subsample of 10 patients who had preoperative CBCT underwent a postoperative CBCT 1 year after immediate implant loading, and 3D superimpositions of pre- and postoperative images were performed. Linear measurements of bone height were performed at two sites in each hemimandible and, on the same sections, bone density according to the qualitative gray values (GVs) was analyzed in an area of 3 mm2 including the cortical mandibular bone.
Results: Fifty-nine fully edentulous patients (31 females, 28 males) with Class VI atrophic mandibles according to Cawood and Howell were rehabilitated with the insertion of four to five short implants (4-mm diameter, 7- or 8.5-mm long). Overall, 251 implants were immediately loaded with a fixed hybrid prosthesis. Four patients did not show up for recall visits, bringing the final number down to 55 patients (31 females, 24 males) and 231 implants. In up to 14 years of follow-up, a total of 4 implant failures were recorded (cumulative survival rate, 98.4%). The biologic complications included 9 mucositis (3.9%) and 3 peri-implantitis (1.3%) at implant-level analysis. Mechanical complications involved 9 chippings of the prosthetic restorations (17.0%). In the 10-patient subsample, the analysis showed bone growth (average of 1.2 ± 0.7 mm) in the posterior areas of the mandible. In addition, bone density was found to increase 17% to 27% with reference to the preoperative CBCT.
Conclusion: The immediate loading of short implants may represent a feasible therapeutic option for the treatment of fully edentulous patients with severely atrophic mandibles. Bone regrowth in the posterior areas and an increase in bone density of the mandible may occur.
