Short implants versus longer implants in augmented posterior mandibles‐ 8‐year results from a RCT

Abstract

Background : Short implants could be an alternative to vertical augmentation procedures when the available bone height does not allow the placement of dental implants longer than 7 mm, however follow-ups longer than 5 years are still lacking. Aim/Hypothesis : To evaluate whether 6.6-mm-long implants could be a suitable alternative to longer implants placed in vertically augmented atrophic posterior mandibles. Material and Methods : Sixty partially edentulous patients having 7–8 mm of residual crestal height and at least 5.5 mm of thickness measured on CT scans above the mandibular canal, were randomly allocated according to a parallel group design, either to receive 1–3 submerged 6.6-mm-long implants or 9.6 mm or longer implants (30 patients per group) placed in vertically augmented bone. Bone was augmented with interpositional anorganic bovine bone blocks fixed with titanium miniplates and covered with resorbable membranes. Grafts were left to heal for 5 months before implant placement. Four months after implant placement, provisional acrylic prostheses were delivered, replaced, after 4 months, by definitive metal- ceramic prostheses. Outcome measures were- prosthetic and implant failures, complications and radiographic peri- implant marginal bone level changes. Patients were followed up to 8 years after loading. Results : Eight years after loading 12 patients dropped out- 5 from the short implant group and 7 from the augmented group. The augmentation procedure failed in 2 patients and only 6.6- mm- long implants could be inserted. There were no statistically significant differences for prosthetic and implant failures. Four prostheses failed in 3 patients of the short implant group versus 3 prostheses in 3 patients of the augmented group (P - value equal to 1.000). Five short implants failed in 3 patients versus 3 long implants in 3 patients ( P - value equal to 1.000). There were statistically more complications in augmented patients (27 complications in 22 augmented patients versus 9 complications in 8 patients of the short implant group) (P - value inferior to 0.001). Eight years after loading, short implant group lost an average of 1.58 mm of peri- implant bone compared with 2.46 mm in the augmented group. Short implants experienced statistically significant less bone loss (0.88 mm) than long implants. Conclusions and Clinical Implications : When residual bone height over the mandibular canal is between 7 and 8 mm, 6.6- mm- short implants are an interesting alternative to vertical augmentation in posterior atrophic mandibles since the treatment is faster, cheaper and associated with less morbidity. [ABSTRACT FROM AUTHOR] Copyright of Clinical Oral Implants Research is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)