Survival of Short and Ultra-Short Locking-Taper Implants Supporting Single Crowns in the Posterior Mandible: A 3-Year Retrospective Study
The purpose of this retrospective study was to determine survival and peri-implant marginal bone loss of short and ultra-short implants placed in the posterior mandible. A total of 98 patients received 201 locking-taper implants between January 2014 and January 2015. Implants were placed with a 2-stage approach and restored with single crowns. Clinical and radiographic examinations were performed at 3-year recall appointments. At that time, the proportion of implant survival by length, and variations of crestal bone levels (mean crestal bone loss and mean apical shift of the “first bone-to-implant contact point” position) were assessed. Significance level was set at 0.05. The total number of implants examined 36 months after loading included: 71 implants, 8.0 mm in length; 82 implants, 6.0 mm in length; and 48 implants, 5.0 mm in length. Five implants failed. The overall proportion of survival was 97.51%, with 98.59% for the 8.0-mm implants, 97.56% for the 6.0-mm implants, and 95.83% for the 5.0-mm implants. No statistically significant differences were found among the groups regarding implant survival (P = .73), mean crestal bone loss (P = .31), or mean apical shift of the “first bone-to-implant contact point” position (P = .36). Single-crown short and ultra-short implants may offer predictable outcomes in the atrophic posterior mandibular regions, though further investigations with longer follow-up evaluations are necessary to validate our results.
Schematic drawing of Bicon dental implant system and its macro-geometric features. (1) Root-plateau form implant body; (2) abutment; (3) 1.5° internal connection (locking-taper); (4) convergent crest module (sloping shoulder); (5) implant plateau.
Figure 2. 3 implants (4.0 × 5.0 mm, 4.0 × 5.0 mm, and 4.0 × 5.0 mm) placed in #21, #19, and #18 sites. (a) Pre-operative radiograph before implant placement. (b) Cone beam computerized tomography obtained before implant placement. Figure 3. 3 implants (4.0 × 5.0 mm, 4.0 × 5.0 mm, and 4.0 × 5.0 mm) placed in #21, #19, and #18 sites. (a) X ray obtained at loading time; (b) X ray obtained at 3-year follow-up. Figure 4. Three implants (4.0 × 5.0 mm, 4.0 × 5.0 mm, and 4.0 × 5.0 mm) placed in #21, #19, and #18 sites. Cone beam computerized tomography obtained at 3-year follow-up.
Figure 5. Three implants (4.0 × 5.0 mm, 4.5 × 6.0 mm, and 4.5 × 6.0 mm) placed in #20, #19, and #18 sites. (a) Pre-operative radiograph before implant placement. (b) X ray obtained at loading time. (c) X ray obtained at 3-year follow-up. Figure 6. One implant (5.0 × 6.0 mm) placed in #19 site. (a) Pre-operative radiograph before implant placement. (b) X ray obtained at loading time. (c) X ray obtained at 3-year follow-up. Figure 7. One implant (5.0 × 8.0 mm) placed in #30 site. (a) Pre-operative radiograph before implant placement. (b) X ray obtained at loading time. (c) X ray obtained at 3-year follow-up.
Schematic example of the references for peri-implant bone levels measurements. (1) Implant-abutment interface; (2) most occlusal point line; (3) crestal bone level (CBL) on the mesial side; (4) CBL on the distal side; (5) first bone-to-implant contact (F-BIC) on the mesial side; (6) F-BIC on the distal side; (7) crown length; (8) implant length.
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