Effect of ridge morphology on guided bone regeneration outcome: conventional tomographic study

This study retrospectively analyzed conventional tomograms to estimate the prognostic value of the cross-sectional ridge morphology on the clinical outcome of guided bone regeneration (GBR).

Presurgical conventional tomograms of 23 single-implant sites were analyzed retrospectively in 20 patients. All sites had a non-space-making buccal dehiscence defect associated with the subsequently placed dental implant. Simultaneous GBR procedures were performed, and 6-month clinical outcomes were assessed. Measurements at baseline and at the 6-month reentry included defect height (from smooth-rough junction to the most apical part of the defect) and horizontal bone gain at three locations (smooth-rough junction, middle, and most apical portion of the defect). All measurements were taken from a reference template. Tomographic parameters included the implant-associated ridge angle and width measured at 6 mm below the alveolar crest and at the most apical point of the implant. Implant exposure and the presence of the barrier membrane were controlled for during statistical analyses.

The presurgical ridge angle had a significant negative correlation with the percentage of defect height reduction (r = -0.621; P = 0.002) and horizontal bone gain (r = -0.469; P = 0.024). This difference remained significant even after controlling for implant/membrane exposure (P = 0.001 and P = 0.019, respectively). A statistically and clinically greater percentage of defect height reduction was observed for ridge angles <28 degrees (P = 0.023). Ridge width did not have a significant effect on the regenerative outcome.

Cross-sectional presurgical ridge angles may have prognostic value in estimating the outcome of simultaneous GBR.