Retrospective Comparative Analysis of Peri-implant Grayscale Values and Marginal Bone Levels in Ultra-Short Implants...

To evaluate peri-implant marginal bone level (MBL) changes and radiographic grayscale value (GSV) alterations in vertically compromised bone around ultra-short implants (5.2 mm) placed in native bone compared to standard-length implants (8 to 14 mm) placed in augmented sites.

A total of 53 patients, collectively receiving 131 implants, were included. Each patient received at least two implants, including one ultra-short implant and one standard-length implant. In total, 78 short implants and 53 standard-length implants were placed. Standard-length implants were predominantly placed using alveolar ridge augmentation with autogenous bone chips, sinus elevation, or retromolar bone block grafting. Autogenous bone chips were supplemented with up to 50% bone substitute materials. Peri-implant MBLs were assessed using the 'distance implant to bone' method, while radiographic GSV served as a surrogate for bone density. All radiographic measurements were performed by two blinded evaluators (P.H., and S.P.) using an automated radiograph overlay protocol, achieving high interrater reliability (intraclass correlation coefficients [ICC] > 0.98). A linear mixed model, accounting for heterogeneous follow-up intervals, was applied to estimate changes in MBLs (ΔMBL) and grayscale values (ΔGSV) (P < .05).

The mean follow-up period was 38 months, with a maximum of 64 months. A total of 131 implants were assessed for ΔMBL and ΔGSV. Ultra-short implants demonstrated significantly lower marginal bone loss over the observation period (ΔMBL = -0.61 ± 0.93 mm) than standard-length implants placed in augmented bone (ΔMBL = -1.11 ± 1.26 mm) (P = .001). Moreover, ΔGSV around ultra-short implants significantly increased (ΔGSV = 3.26 ± 20.52 arbitrary units [a.u.]), whereas standard-length implants exhibited a decrease in radiographic density (ΔGSV = -0.76 ± 21.59 a.u.) (P = .009).

Within the limitations of this midterm retrospective study, ultra-short implants placed in native bone exhibited statistically superior marginal bone preservation and significantly increased radiographic density when compared to standard-length implants placed in augmented sites. These results underscore the potential clinical advantage of opting for ultra-short implants in suitable native bone conditions to reduce the morbidity associated with extensive augmentation and lessen the risk of peri-implantitis in the long term. Nevertheless, further long-term randomized investigations are warranted to confirm these findings.