Dimensional alterations of extraction sites after different alveolar ridge preservation techniques - a volumetric study

Objectives The aim of this randomized controlled clinical study was to assess soft tissue contour changes after different alveolar ridge preservation procedures. Material and Methods Following tooth extraction, 30 patients were randomly assigned to the following treatments (Tx) - Tx 1: xenogenic bone substitute (pre-hydrated collagenated cortico-cancellous porcine bone) and free gingival graft; Tx 2: free gingival graft alone; Tx 3: xenogenic bone substitute; Tx 4: no further treatment (control). Impressions were obtained before tooth extraction (baseline) and 4 months after surgery. Cast models were optically scanned, digitally superimposed and horizontal measurements of the contour alterations between time points were performed using digital imaging analysis. Results All groups displayed contour shrinkage at the buccal aspect ranging from a mean horizontal reduction of -0.8 +/- 0.5mm (Tx 1) to -2.3 +/- 1.1mm (control). Statistically significant differences were found between Tx 1 and Tx 4 as well as Tx 2 and Tx 4. A significant positive influence of the free gingival graft on the maintenance of the ridge width was recorded (p<0.001). Conclusion In this study, alveolar ridge preservation techniques were not able to entirely compensate for alveolar ridge reduction. Covering the orifice of the extraction socket with a free gingival tissue graft seems to have the potential to limit but not avoid the post-operative external contour shrinkage based on optical scans.