Effect of time in function on the predictability of short dental implants (≤6 mm): A meta‐analysis

Abstract

Purpose To analyse randomised controlled clinical trials (RCTs) and prospective cohort studies reporting on the survival and failure rates of functionally loaded short implants (SI) based on the actual length of time in function. Materials and methods This meta‐analysis was conducted according to PRISMA guidelines for systematic reviews. Electronic and manual searches were conducted to identify RCTs and prospective cohort studies reporting survival and complication rates of short dental implants (≤6 mm) based on the time in function. Secondary outcomes included the location (maxilla or mandible), type of restoration (single crown [SC] versus fixed dental prosthesis [FDP]) and marginal bone loss (MBL). Results A total of 20 studies (11 RCTs and 9 prospective) fulfilled the inclusion criteria and featured a total of 1238 SI placed in 747 patients. The overall (early and late) mean percentage of short implant failure was 4%. SI with up to 1‐year follow‐up presented failure rate of 2%, while SI followed up for >3 years showed a failure rate of 10%. SI restored with SC presented a late failure rate of 4% while SI restored with FPD 2%. The late failure rate did not differ in terms of location (maxilla or mandible) both with 3%. Conclusion Short implants in function for more than 3 years presented higher failure rates compared to SI in function for <3 years. Splinting crowns supported by SIs in the posterior area should be considered. However, SI is a valid option for selected cases given their relatively high long‐term survival rates.

Sinus Floor Elevation via an Osteotome Technique without Biomaterials

“…These authors stress the importance of "undersizing" the implant site in order to obtain correct primary stability. Placement of short implants in these situations have similar survival results resulting in 96% survival rates [35].…”

A 4 mm-Long Implant Rehabilitation in the Posterior Maxilla with Dynamic Navigation Technology: A Case Report after a Three-Years Post-Loading Follow-Up

“…In 2020, Rameh et al, limiting the inclusion criteria to a minimum of five-year follow-up, reported for 5/6 mm-long implants, an average of 95.54%, ranging between 86.7 and 98.5%, survival rate in the maxilla, and a 94.39%, ranging between 86.7 and 100%, in mandible [ 7 ]. Vazouras et al, including the studies on ≥4 and ≤6 mm ultra-short implants with a minimum follow-up of three years, calculated a 4% overall failure increasing to 10% after that [ 9 ]. The first reports on 4 mm ultra-short implants in posterior mandibles found a survival rate of 95.7% and 92.3%, after one and two years, respectively [ 35 ].…”

“…All the studies convey that short implants could be a better choice considering the morbidity, the costs, and the duration of the reconstructive approaches. Nevertheless, a time-dependent higher risk of failure of ≤6 mm-long implants emerged, with a wide range of the survival rates, from 86.7% to 100%, and a calculated 24% higher risk for 1–5 years follow-up than with longer implants [ 9 ]. Regarding ≥5 years of loading of ≤5 mm-long screws, the literature is so far insufficient to recommend this approach [ 39 ].…”

“…Hence, the definition of “short implant” changed from ≤10 mm to 6 mm [ 4 , 5 ] up to the “ultra-short” measure of 4 mm in length. Systematic reviews on ≤6 mm-short implants report a range of 90–98.5% of the mean survival rate values in posterior maxilla up to 5 years [ 5 , 6 , 7 , 8 , 9 ]. Regarding 4 mm short implants, only two randomized controlled trials (RCTs), both in the mandible, report good outcomes in atrophic bone, compared to reconstructed sites with one-year follow-up [ 10 , 11 ].…”

Survival Rate of 1008 Short Dental Implants with 21 Months of Average Follow-Up: A Retrospective Study

“…Although the results of our study presented high survival rates at the two-year follow-up for the different types and lengths of the evaluated implants, caution should be taken when assessing the obtained results since failure rates could depend on time in function. A recently published meta-analysis [53] evaluated the short implants' (≤6 mm) failure rates based on time in function, and the results demonstrated a time-dependent decrease in the survival rate of single short implants in the posterior area. Furthermore, some long-term studies reported that, between the third and fifth years in function, the risk of short implant failure increases significantly [33,44].…”