Immediate full-arch mandibular rehabilitation supported by four implants: A retrospective study with 20 to 25 years of follow-up.

OBJECTIVES

This study evaluated the 20 to 25 years clinical and radiographic outcomes of immediate full-arch mandibular rehabilitations supported by four implants (two axial anterior implants and two tilted posterior implants).

MATERIALS AND

METHODS

One-hundred-eighty-one patients (108 females; 73 males) with a mean age of 59.2 years ±11.9 years, with mandibular rehabilitations through the All-on-4 concept, were rehabilitated with 724 dental implants in immediate function, supporting 181 fixed full-arch prostheses. The mean follow-up time was 264 months (range 240-321). Primary outcomes measures were implant survival and success and prosthesis survival. Secondary outcome measures were marginal bone loss at the 20 and 25-year follow-up, mechanical and biological complications. Estimation of risk indicators through multivariable analysis was performed for implant failure (Cox regression), marginal bone loss > 3 mm at 20 years, biological and mechanical complications (binary logistic regression).

RESULTS

One-hundred patients were lost to follow-up. Seventy-seven patients presented for the 20-year follow-up while 3 patients presented for the 25-year follow-up. The cumulative survival rate for implants and prostheses was 90 % and 92 %, respectively, up to 25-years follow-up. The mean marginal bone loss at 20 years and 25 years was 1.71 mm ±1.98 mm and 2.28 mm ±2.07 mm, respectively. The incidence of mechanical complications was 70.7 % at patient level; while the incidence of biological complications was 24.9 % and 11.6 % at patient and implant level, respectively. Risk indicators negatively affected the outcome implant failure (biological complications and type of restorative material), mechanical complications (males), and biological complications (smoking and previous failure of a contiguous implant).

CONCLUSIONS

The immediate mandibular full-arch rehabilitation supported by four implants (two axial anterior implants and two tilted posterior implants) is a safe and reliable protocol on the very long term.

CLINICAL SIGNIFICANCE: The present study describes the very-long term evaluation of full-arch implant-supported rehabilitations through the All-on-4 Concept between 20 and 25 years of follow-up. The high implant and prosthetic survival allow to safely consider this concept as a viable treatment option for edentulous patients; nevertheless, proper pre-treatment risk assessments and post-treatment maintenance and prosthetic protocols are paramount to achieve and maintain success.