Ridge split vs. bone expansion: which technique costs more crestal bone at 12 months?

Alveolar ridge resorption following tooth loss remains one of the central challenges in implant rehabilitation. When residual ridge width is insufficient, clinicians must choose between bone expansion and ridge split techniques — yet the impact of these preparatory approaches on long-term crestal bone stability has not been rigorously compared head-to-head. This prospective comparative study addressed precisely that question.

Seventy-two implant sites were enrolled across patients aged 25–55 years requiring implant-supported rehabilitation. Sites were allocated equally to three groups (n=24 each): conventional drilling (CD), bone expansion (BE), and ridge split (RS). Crestal bone levels were assessed via CBCT at baseline (immediately post-placement) and at 3, 6, and 12 months. Both mesial and distal crestal bone loss were measured and analyzed using one-way ANOVA with Tukey's post hoc test for intergroup comparisons and repeated-measures ANOVA for intragroup longitudinal analysis.

All three groups exhibited progressive crestal bone loss over the 12-month observation period. Intergroup differences were statistically significant at every time point (p < 0.001). The ridge split group recorded the highest bone loss values, followed by the bone expansion group; conventional drilling consistently showed the least crestal resorption. Pairwise comparisons between all three groups were likewise significant (p < 0.001). Within-group analysis confirmed a significant increase in bone loss over time in all groups, with one notable exception: in the conventional drilling group, the difference between 6 and 12 months did not reach statistical significance, suggesting that remodeling in this group tends to stabilize after the first six months.

These findings carry direct clinical implications. Conventional drilling, performed in ridges of adequate width, produces the most favorable peri-implant bone response — a predictable outcome consistent with established biomechanical principles, as the native bone architecture is preserved and thermal or mechanical trauma is minimized. Ridge split, while indispensable when ridge width is critically deficient, appears to induce greater and more prolonged bone remodeling, likely as a consequence of the cortical osteotomy, the mechanical stress distribution, and the healing dynamics of a mobilized buccal plate. Bone expansion occupies an intermediate position, offering a less traumatic alternative to ridge split when moderate width deficiency is present.

For the practicing implantologist, the take-home message is nuanced: technique selection must be driven by ridge anatomy, but clinicians should counsel patients treated with ridge split or bone expansion about the likelihood of greater early crestal bone remodeling and factor this into prosthetic planning and follow-up protocols. Longer-term data beyond 12 months — and studies correlating bone loss with implant survival and prosthetic outcomes — will be essential to consolidate these conclusions.