Ten-Year Performance of Posterior 6-mm Implants with Single-Tooth Restorations: A Randomized Controlled Trial

Abstract

The aim of the study was to compare the clinical and radiographic outcomes of short dental implants (6-mm test group, TG) to longer implants (10-mm control group, CG) with single crown restorations after 10 y of loading. Patients requiring single-tooth replacement in the posterior jaws were randomly assigned to TG or CG. Implants were loaded with screw-retained single crowns after a healing period of 10 wk. Follow-up appointments were scheduled yearly and comprised patient-adapted oral hygiene reinstructions and polishing of all teeth and implants. After 10 y, clinical and radiographical parameters were assessed again. Out of initially 94 patients (47 in TG and CG, each), 70 (36 TG and 34 CG) could be reassessed. Survival rates accounted for 85.7% (TG) and 97.1% (CG), without significant intergroup difference ( P = 0.072). All but 1 lost implant had been located in the lower jaw. These implants were not lost due to peri-implantitis but due to a late loss of osseointegration without signs of inflammation and with actually stable marginal bone levels (MBLs) over the investigation period. In general, MBLs were stable with medians (interquartile ranges) of 0.13 (0.78) mm and 0.08 (1.2) mm, for TG and CG, without significant intergroup differences. Crown-to-implant ratio showed a highly significant intergroup difference of 1.06 ± 0.18 mm and 0.73 ± 0.17 mm ( P < 0.001). Few technical complications (i.e., screw loosening or chipping) were registered during the investigation period. In conclusion, given stringent professional maintenance, short dental implants with single-crown restorations show a slightly worse but statistically not different survival rate after 10 y, especially in the lower jaw, but can still be considered a valuable alternative, especially when vertical bone dimensions are limited (German Clinical Trials Registry: DRKS00006290).

Single crown restorations supported by 6‐mm implants in the resorbed posterior mandible: A 10‐year prospective case series

“…The present study's 100% implant survival rate is higher than that of Rossi and colleagues, 12 being 91.7% of the implants in both the maxilla and mandible, and also higher than the 6-mm implants in the Sahrmann and colleagues study, 13 being 85.7% of the implants in both the maxilla and mandible. The precise implant survival rate in the mandible could not be calculated from the latter studies, although Sahrmann and colleagues 13 mentioned that most implants were lost in the mandible. However, one has to keep in mind that the loss of a small number of implants constitutes a relatively high failure rate as the cohort sizes were small.…”

“…A 10-year study focusing solely on 6-mm implants supporting single restorations in the mandible has not been published before. Therefore, the best 10-year follow-up studies for comparison purposes are those of Rossi and colleagues, 12 reporting 6 implants with solitary restorations in the posterior maxillary and mandibular region, and of Sahrmann and colleagues, 13 reporting a randomized controlled trial comparing solitary restorations in the posterior maxillary and mandibular region supported by either 6-mm implants or 10-mm implants.…”

“…Rossi and colleagues and Sahrmann and colleagues are the only authors who have published 10-year outcomes of 6-mm implants supporting solely solitary restorations in the maxillary and mandibular posterior region. 12,13 The overall implant survival rate of implants placed in either the maxilla or mandible was 91.7% in the study of Rossi and colleagues 12 and 85.7% in the study of Sahrmann and colleagues. 13 A prospective longterm study with an evaluation period of at least 10 years, focusing on short implants with solitary restorations in the resorbed posterior mandible, is missing.…”

“…12,13 The overall implant survival rate of implants placed in either the maxilla or mandible was 91.7% in the study of Rossi and colleagues 12 and 85.7% in the study of Sahrmann and colleagues. 13 A prospective longterm study with an evaluation period of at least 10 years, focusing on short implants with solitary restorations in the resorbed posterior mandible, is missing. Therefore, we performed a 10-year prospective two-center case series to evaluate the clinical performance of 6-mm implants restored with solitary restorations in the mandibular posterior region.…”

Randomized controlled multi‐centre study comparing shorter dental implants (6 mm) to longer dental implants (11–15 mm) in combination with sinus floor elevation procedures: 10‐year data

“…Although encouraging data have been reported for shorter dental implants and specific implant systems in the mid-term (≤5 years) (Papaspyridakos et al, 2018;Ravida et al, 2019;Thoma, Zeltner, et al, 2015), longer term outcomes have been less favourable, thereby questioning their clinical applicability and indications. In a recently published RCT comparing shorter and longer dental implants placed in the posterior mandible and maxilla, shorter dental implants resulted in a significantly lower survival rate at 10 years (Sahrmann et al, 2023). Major differences between the latter study and the present multi-centre RCT are the implant system, the available bone height, the location (mandible, maxilla) and the type/material of the restorations.…”