Effect of Ridge Morphology on Guided Bone Regeneration Outcome: Conventional Tomographic Study

Background: 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). Methods: 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. Results: 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 <280 (P = 0.023). Ridge width did not have a significant effect on the regenerative outcome. Conclusion: Cross-sectional presurgical ridge angles may have prognostic value in estimating the outcome of simultaneous GBR. J Periodontol 2009;80:1231-1236.