A cone beam tomographic evaluation of hard tissue alterations at immediate implants: a clinical prospective study.

The aim of this study was to investigate the hard tissue alterations of the alveolar bone crest following tooth extraction and immediate implant placement using cone beam computed tomography. Twelve consecutive patients in need of an immediate dental implant were included in the study. An implant of proper length was placed in the extraction socket with the coronal margin of the rough surface generally flush with or deeper than the buccal alveolar bone crest. All patients underwent a radiologic examination both immediately after implant placement (T1) and at the time of reentry 4 months after surgery (T2). The survival rate of 12 immediate implants at 4 months was 100%. Only 9 of 12 patients completed the study. The comparison between tomographies performed at T1 and T2 showed substantial variations in alveolar bone, mainly at the buccal aspect, registering a vertical gain of about 3.2 mm. The horizontal resorption of the alveolar bone crest appeared to be more marked at the buccal than at the lingual aspects. At the buccal aspect, the resorption was 1.9 mm, 1.0 mm, and 0.6 mm at the measurements performed at 1, 3, and 5 mm apical to the crest, respectively. At the lingual aspect, the corresponding values were 0.6 mm, 0.7 mm, and 0.5 mm, respectively. The bone crest area was more or less the same at T1 and T2, while the total area decreased after 4 months of healing but was not statistically significant. The results should be viewed with caution because of the small number of cases examined. The results confirm the success of immediate implant placement.