Using Cone Beam Computed Tomography Angle for Predicting the Outcome of Horizontal Bone Augmentation

Background: The aim of this study was to assess the influence of ridge morphology on the amount of horizontal bone augmentation achieved with the sandwich bone augmentation (SBA) technique in the reconstruction of buccal dehiscence defects on dental implants. Methods: Cone beam computed tomography (CBCT) was used to assess bone width changes in 26 patients who participated in a randomized controlled trial conducted in 2008 to 2011. The amount of horizontal bone gain was evaluated at four different levels (3, 6, 9, and 12mm apical to the alveolar crest) and three different time points (T1: baseline, T2: at time of graft placement, and T3: 6 months later). Different morphological characteristics of the alveolar ridge were also evaluated to determine their influence on horizontal bone augmentation. A total of 78 CBCT scans were assessed. Results: Comparison of the changes in ridge morphology at all measurement locations showed an overall ridge width gain of 2.30±2.20mm after 6 months. The use of membranes and the angulation of the concavity played a role in influencing the outcomes of the SBA technique. Critical crest angulation (CA) is 150° for bone gain at 9mm apical to the crest. When CA is smaller than 150°, the horizontal bone gain was 4.3±2.2mm; if CA is greater than 150°, the gain was significantly lower at 1.3±1.7mm (p=.001). Conclusions: SBA is a reliable and predictable technique to gain horizontal ridge width with simultaneous implant placement. Crest ridge angulation can be used as a tool to predict bone gain at 9mm apical to the bone crest.