Horizontal ridge augmentation: tunneling holds its own against the flap

Clinical question. In horizontal augmentation of the atrophic alveolar ridge, does surgical access change the result? The authors compared a conventional full-thickness flap with a tunneling approach, using freeze-dried bone allograft (FDBA) combined with injectable platelet-rich fibrin (i-PRF) in every site, and asked a second question within the tunnel: does a barrier membrane still add anything when the flap is never fully raised?

Methodology. Forty-five patients were randomly allocated to three arms of fifteen: conventional flap with a resorbable collagen membrane (CF), tunneling with membrane (TM), and tunneling without membrane (TnM). Ridge width was measured on CBCT before surgery and again six months later; a histomorphometric analysis was performed at re-entry. Forty-three patients entered the statistical analysis.

Findings. All three groups gained ridge width at six months. At the 2 mm level the mean gain was 1.28 mm (95% CI 0.17 to 2.40) with tunneling plus membrane, 2.85 mm (95% CI 1.80 to 3.89) with tunneling without membrane, and 1.95 mm (95% CI 1.07 to 2.83) with the conventional flap. No statistically significant difference emerged between the groups (p > 0.05), and histomorphometry pointed the same way: comparable bone quality across all three techniques, with no significant intergroup differences.

Clinical relevance. Within the limits of a single six-month trial, the tunnel appears to be a workable alternative to the conventional flap for horizontal augmentation, and the membrane did not prove indispensable once the graft was contained inside a tunnel. Two cautions belong with the result. First, the trial was designed as a comparison, not as an equivalence or non-inferiority study: the absence of a significant difference across three arms of fifteen patients is not the same as proof that the techniques are interchangeable, and the confidence intervals are wide enough to accommodate clinically meaningful gaps. Second, six months and a single centre describe early healing, not the behaviour of the graft under load over years. The practical reading is permissive rather than prescriptive: where the defect allows it, a tunnel is a defensible choice, with the usual advantages of an intact periosteal envelope and tension-free closure.