Immediate loading of 2 (all-on-2) flapless-placed mandibular implants supporting cross-arch fixed prostheses: interim data from a 1-year follow-up prospective single cohort study

Purpose: To evaluate the clinical outcome of 2 implants placed flapless in fully edentulous mandibles and immediately restored with a metal-resin screw-retained cross-arch prosthesis 1 year after loading. Materials and methods: Eighty consecutive patients were recruited. To be immediately loaded, implants had to be inserted with a minimum torque of 80 Ncm. Outcome measures, evaluated by two independent assessors, were prosthesis and implant failures, complications, marginal bone level changes, implant stability quotient (ISQ) values and patient satisfaction. Results: Flaps were raised in 7 patients. Twelve implants in 7 patients did not reach the planned insertion torque. Four implants in 3 patients were immediately replaced by larger diameter implants and achieved the desired torque, whereas the remaining implants were immediately loaded anyway. Two implants failed early in 2 patients, but were successfully replaced and their prostheses remade. One month after loading, 72 (90%) patients declared to be completely satisfied with the therapy, 7 (9%) partially satisfied and 1 (1%) unsatisfied. One year after loading, all prostheses were in function, though one patient did not attend the 1-year control. Eight (10%) complications occurred, all successfully treated. After 1 year, the mean marginal bone loss was 0.3 mm and mean ISQ values decreased from 75.4 to 72.4. Conclusions: These short-term results at 1 year after loading suggest that immediately loaded mandibular cross-arch fixed prostheses can be supported by only 2 dental implants. Longer follow-ups (around 10 years) are needed to know the prognosis of this treatment modality. Keywords: cohort study, dental implants, flapless, immediate loading