Short vs Long Dental Implants for the Fixed Rehabilitation of the Fully Edentulous Mandible

Short vs Long Implants Supporting a Total Fixed Prosthetic Rehabilitation of the Fully Edentulous Mandible. A Multicenter Randomized Controlled Clinical Trial

The aim of this study is to clinically and radiographically compare the performance of short (6 mm-long) versus long (≥11 mm-long) dental implants placed in the interforaminal region of fully edentulous mandibles, supporting a screw-retained full-arch cantilever bridge.

The use of short dental implants provides undeniable benefits in sites where the reduced available volume would otherwise need bone augmentation procedures and their use has greatly expanded in the recent years. However, well designed clinical trials which provide a sound evidence of their performance and reliability are still lacking to date. In this post-market, multi-center, open, parallel-group, randomized, controlled clinical trial the investigators aim to to clinically and radiographically compare the performance of short (6 mm-long) versus long (≥11 mm-long) dental implants supporting a mandibular screw-retained full-arch cantilever bridge. Five 4mm-wide/6mm-long (test) or 4mm-wide/≥11mm-long (control) titanium dental implants (Osseospeed™, ASTRA TECH Implant System™, Dentsply Sirona) are placed in the interforaminal region of fully edentulous mandibles, in non-regenerated sites, with at least 1 mm of peri-implant bone circumferentially. All products are CE (European Conformity) marked and used within their intended use. Two-Stage surgery is performed, implants are positioned in healed bone and exposed after 3 months to be connected with the prosthesis. This is a medium-term follow-up study including evaluations also at 1 and 3 years from the baseline. Three italian centers participate: Naples (University of Campania "Luigi Vanvitelli"), Naples (AORN "A. Cardarelli"), Catania (Private Office). The study protocol has been approved by the Institutional Review Board of the University of Campania "Luigi Vanvitelli".

A full-arch screw-retained mandibular prosthesis with distal cantilevers supported by five interforaminal short implants (ASTRA TECH Implant System, OsseoSpeed™ 4.0 S, length: 6mm)

A full-arch srew-retained mandibular prosthesis with distal cantilevers supported by five interforaminal short implants (ASTRA TECH Implant System, OsseoSpeed™ 4.0 S, length: ≥11mm)

Rehabilitation of the edentulous mandible by a full-arch srew-retained prosthesis with distal cantilevers supported by five interforaminal short implants (ASTRA TECH Implant System, OsseoSpeed™ 4.0 S, length: 6 mm)

Rehabilitation of the edentulous mandible by a full-arch srew-retained prosthesis with distal cantilevers supported by five interforaminal long implants (ASTRA TECH Implant System, OsseoSpeed™ 4.0 S, length: ≥11mm)

Marginal bone level (MBL) is measured as the distance in millimiters calculated on periapical radiographs from the implant neck to the most coronal bone-to-implant contact point at both the mesial and the distal side of each implant. The radiographs will be taken with an X-ray apparatus supplied with a long cone and Rinn's film holders.

A surviving implant is defined as an implant in place at the time of the follow-up. Any implant loss shall be assessed as an early loss (implant fails before being osseointegrated) or late loss (after being osseointegrated).

Inclusion Criteria: total edentulous patients in the lower region since at least 8 months, sufficient amount of native bone (no augmentation procedures) in the recipient sites to allow ≥11 mm long and 4 mm wide implant installation (≥1 mm of peri-implant bone circumferentially) systemic health compliance with good oral hygiene informed consent signed. Exclusion Criteria: any disease, medication or drug that could jeopardize healing, osseointegration or treatment outcome, untreated caries or periodontitis of the remaining teeth, mucosal and bone tissue lesions, severe bruxism or other parafunction habits, unrealistic aesthetic demands, patient taking part to another study

Albrektsson T, Zarb G, Worthington P, Eriksson AR. The long-term efficacy of currently used dental implants: a review and proposed criteria of success. Int J Oral Maxillofac Implants. 1986 Summer;1(1):11-25. No abstract available.

Nisand D, Renouard F. Short implant in limited bone volume. Periodontol 2000. 2014 Oct;66(1):72-96. doi: 10.1111/prd.12053.

Ekelund JA, Lindquist LW, Carlsson GE, Jemt T. Implant treatment in the edentulous mandible: a prospective study on Branemark system implants over more than 20 years. Int J Prosthodont. 2003 Nov-Dec;16(6):602-8.

Srinivasan M, Vazquez L, Rieder P, Moraguez O, Bernard JP, Belser UC. Survival rates of short (6 mm) micro-rough surface implants: a review of literature and meta-analysis. Clin Oral Implants Res. 2014 May;25(5):539-45. doi: 10.1111/clr.12125. Epub 2013 Feb 18.

Laurell L, Lundgren D. Marginal bone level changes at dental implants after 5 years in function: a meta-analysis. Clin Implant Dent Relat Res. 2011 Mar;13(1):19-28. doi: 10.1111/j.1708-8208.2009.00182.x.